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, (1996), Climate Monitoring and Diagnostics Laboratory No.23 Summary Report 1994-1995, Abstract The Climate Monitoring and Diagnostics Laboratory (CMDL) is located in Boulder, Colorado, with observatories in Barrow, Alaska; Mauna Loa, Hawaii; Cape Matatula, American Samoa; and South Pole, Antarctica. It is one of twelve components of the Environmental Research Laboratories (ERL) within the Office of Oceanic and Atmospheric Research (OAR) of the National Oceanic and Atmospheric Administration (NOAA). CMDL conducts research related to atmospheric constituents that are capable of forcing change in the climate of the earth through modification of the atmospheric radiative environment, for example greenhouse gases and aerosols, and those that may cause depletion of the global ozone layer. This report is a summary of activities of CMDL for calendar years 1994 and 1995. It is the 23rd consecutive report issued by this organization and its Air Resources Laboratory/Geophysical Monitoring for Climatic Change predecessor since formation in 1972. From 1972 through 1993 (numbers 1 through 22), reports were issued annually. However, with this issue we begin a 2-year reporting cycle, which stems from a need to most efficiently use the time and financial resources of our staff and laboratory and from a general trend towards electronic media. In this respect, CMDL has developed a comprehensive internet home page during the past 2 years. There you will find information about our major groups and observatories, latest events and press releases, publications, data availability, and personnel. Numerous data graphs and ftp data files are available. The URL address is http://www.cmdl.noaa.gov. Information (program descriptions, accomplishments, publications, plans, data access, etc.) on CMDL parent organizations can best be obtained via the internet. Their URL addresses are ERL: http://www.erl.noaa.gov; OAR: http://www.oar.noaa.gov; NOAA: http://www.noaa.gov. In 1995, Eldon Ferguson retired from federal service and from the CMDL Director's position that he held from the formation of the Laboratory in 1990. On a personal note, we extend to him our best wishes for the future and our thanks for scientific guidance and direction in the past. In 1996, David Hofmann, the CMDL Chief Scientist since 1990, was appointed Director of CMDL. This report is organized into the following major sections: 1. Observatory, Meteorology, and Data Management 2. Carbon Cycle 3. Aerosols and Radiation 4. Ozone and Water Vapor 5. Nitrous Oxide and Halocompounds 6. Cooperative Programs These are followed by a list of CMDL staff publications for 1994-1995
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Andrews, E., J. A. Ogren, P Bonasoni, A Marinoni, E Cuevas, S Rodriguez, J Sun, D.A Jaffe, E Fischer, U Baltensperger, E Weingarten, M Collaund Coen, S Sharma, A.M Macdonald, W.R Leaitch, N Lin, P Laj, T Arsov, I Kalapov, A Jefferson and P. J. Sheridan, (2011), Climatology of aerosol radiative properties in the free troposphere, Atmospheric Research, 102, 4, , 10.1016/j.atmosres.2011.08.017 Abstract High altitude mountaintop observatories provide the opportunity to study aerosol properties in the free troposphere without the added expense and difficulty of making airborne measurements. Climatologies for free tropospheric aerosol radiative properties in cloud-free air, including light scattering, light absorption, light extinction, single scattering albedo, Ångström exponent, hemispheric backscatter fraction and radiative forcing efficiency, from twelve high altitude (2.2–5.1 km) measurement platforms are presented at low relative humidity and at standard temperature and pressure. These climatologies utilize data from ten mountaintop observatories in the 20–50°N latitude band:Mauna Loa, USA; Lulin Mountain, Taiwan; Nepal Climate Observatory— Pyramid; Izaña, Spain; Mount Waliguan, China; Beo Moussala, Bulgaria; Mount Bachelor, USA; Monte Cimone, Italy; Jungfraujoch, Switzerland; Whistler Mountain, Canada. Results are also included from two multi-year, in-situ aerosol vertical profiling programs: Southern Great Plains, USA and Bondville, USA. The amount of light absorption and scattering observed at these high altitude sites either peaks in the spring or it has a broad spring to summer enhancement. The seasonal variation of the aerosol single scattering albedo, backscatter fraction and Ångström exponent changes from site to site but the timing can be related to aerosol sources and transport processes known to impact the individual sites. The seasonal variation of in-situ aerosol light extinction from these high altitude measurements is in excellent agreement with extinction values derived from CALIPSO lidar measurements. Analysis of the systematic variability among in-situ aerosol properties shows that these relationships can be used to infer aerosol types. In particular, the relationship between single scattering albedo and Ångström exponent can indicate the presence of dust aerosol. Radiative forcing efficiency (RFE=aerosol forcing/aerosol optical depth) is used to assess the importance of single scattering albedo and backscatter fraction on aerosol forcing by eliminating aerosol amount (i.e., aerosol optical depth) fromthe calculation. Variability inmonthly cycles of RFE corresponds with changes in single scattering albedo and hemispheric backscatter fraction. Utilizing site-specific, climatological values of single scattering albedo and backscatter fraction to calculate RFE results in departures from the monthly median values of RFE typically in the range 10–30%. The greatest discrepancy occurs formonths with lowaerosol loadingwhere the observed variability of single scattering albedo and backscatter fraction is the greatest. At most sites the radiative forcing efficiency at low aerosol loading (light scattering < 10 Mm^-1) is slightly less negative (more warming) than at higher aerosol loading.
Antu�a, J. C., A. Robock, G. L. Stenchikov, L. W. Thomason and J. Barnes, (2002), Lidar validation of SAGE II aerosol measurements after the 1991 Mount Pinatubo eruption, Journal of Geophysical Research-Atmospheres, 107, D14, 4194-4194, doi: 10.1029/2001JD001441 Abstract [1] After the Mount Pinatubo volcanic eruption on 15 June 1991 the Stratospheric Aerosol and Gas Experiment (SAGE) II instrument made extensive aerosol extinction retrievals using the limb-viewing technique. In regions of high-aerosol loading, SAGE II was not able to make measurements, resulting in large information gaps both in latitudinal and in longitudinal coverage as well as in the vertical. Here we examine the possibility of filling the vertical gaps using lidar data. We compare every coincident backscattering measurement (at a wavelength of 0.694 �m) from two lidars, at Mauna Loa, Hawaii (19.5�N, 155.6�W), and at Hampton Virginia (37.1�N, 76.3�W), for the 2-year period after the Pinatubo eruption with the SAGE II version 6.0 extinctions at 0.525 and 1.02 �m wavelengths. This is the most comprehensive comparison ever of lidar data with satellite data for the Pinatubo period. We convert backscattering to extinction at the above wavelengths. At altitudes and times with coincident coverage, the SAGE II extinction measurements agree well with the lidar data but less so during the first six months after the eruption, due to the heterogeneity of the aerosol cloud. This shows that lidar data can be combined with satellite data to give an improved stratospheric aerosol data set.
Antu�a, J. C., A. Robock, G. Stenchikov, J. Zhou, C. David, J. Barnes and L. Thomason, (2003), Spatial and temporal variability of the stratospheric aerosol cloud produced by the 1991 Mount Pinatubo eruption, Journal of Geophysical Research-Atmospheres, 108, D20, 4624-4624, doi:10.1029/2003JD003722 Abstract [1] As a critical quality control step toward producing a stratospheric data assimilation system for volcanic aerosols, we conducted a comparison between Stratosphere Aerosol and Gas Experiment (SAGE) II aerosol extinction profiles and aerosol backscatter measured by five lidars, both in the tropics and midlatitudes, for the two-year period following the 1991 Mt. Pinatubo eruption. The period we studied is the most challenging for the SAGE II retrieval because the aerosol cloud caused so much extinction of the solar signal that in the tropics few retrievals were possible in the core of the cloud. We compared extinction at two wavelengths at the same time that we tested two sets of conversions coefficients. We used both Thomason and J�ger's extinction-to-backscatter conversion coefficients for converting lidar backscatter profiles at 0.532 ?m or 0.694 ?m wavelengths to the SAGE II extinction wavelengths of 0.525 ?m and 1.020 ?m or the nearby ones of 0.532 ?m and 1.064 ?m respectively. The lidars were located at Mauna Loa, Hawaii (19.5�N, 155.6�W), Camag�ey, Cuba (21.4�N, 77.9�W), Hefei, China (31.9�N, 117.2�W), Hampton Virginia (37.1�N, 76.3�W), and Haute Provence, France (43.9�N, 5.7�W). For the six months following the eruption the aerosol cloud was much more heterogeneous than later. Using two alternative approaches, we evaluated the aerosol extinction variability of the tropical core of the Pinatubo stratospheric aerosol cloud at the timescale of 1�2 days, and found it was quite large. Aerosol variability played the major role in producing the observed differences between SAGE II and the lidars. There was in general a good agreement between SAGE II extinction measurements and lidar derived extinction, and we conclude that all five lidar sets we compared can be used in a future data assimilation of stratospheric aerosols. This is the most comprehensive comparison yet of lidar data with satellite data for the Pinatubo period.
Atlas, E., B. Ridley, J. Walega, J. Greenberg, G. Kok, T. Staffelbach, S. Schauffler, J. Lind, G. Hubler, R. Norton, S. Liu, D. Davis, A. Bandy, D. Blake, J. Bradshaw, E. Browell, J. Collins, G. Gregory, B. Heikes, Y. Kondo, G. Sachse, S. Sandholm, H. Singh, B. Talbot, Ed J. Dlugokencky, James W. Elkins, Samuel J. Oltmans, G. Mackay and D. Karecki, (1996), A comparison of aircraft and ground-based measurements at Mauna Loa observatory, Hawaii, during GTE PEM-west and MLOPEX 2, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 101, D9, 14599-14612, Paper number 96JD00213 Abstract During October 19-20, 1991, one flight of the NASA Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM-West A) mission was conducted near Hawaii as an intercomparison with ground-based measurements of the Mauna Loa Observatory Photochemistry Experiment (MLOPEX 2) and the NOAA Climate Modeling and Diagnostics Laboratory (CMDL). Ozone, reactive nitrogen species, peroxides, hydrocarbons, and halogenated hydrocarbons were measured by investigators aboard the DC-8 aircraft and at the ground site. Lidar cross sections of ozone revealed a complex air mass structure near the island of Hawaii which was evidenced by large variation in some trace gas mixing ratios. This variation limited the time and spatial scales for direct measurement intercomparisons. Where differences occurred between measurements in the same air masses, the intercomparison suggested that biases for some trace gases was due to different calibration scales or, in some cases, instrumental or sampling biases. Relatively large uncertainties were associated with those trace gases present in the low parts per trillion by volume range. Trace gas correlations were used to expand the scope of the intercomparison to identify consistent trends between the different data sets.
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Barnes, J., S. Bronner, R. Beck and N.C. Parikh, (2003), Boundary Layer Scattering Measurements with a Charge-Coupled Device Camera Lidar, Applied Optics, 42, 15, 2647-2652, doi:10.1364/AO.42.002647 Abstract A CCD-based bistatic lidar (CLidar) system has been developed and constructed to measure scattering in the atmospheric boundary layer. The system uses a CCD camera, wide-angle optics, and a laser. Imaging a vertical laser beam from the side allows high-altitude resolution in the boundary layer all the way to the ground. The dynamic range needed for the molecular signal is several orders of magnitude in the standard monostatic method, but only approximately 1 order of magnitude with the CLidar method. Other advantages of the Clidar method include low cost and simplicity. Observations at Mauna Loa Observatory, Hawaii, show excellent agreement with the modeled molecular-scattering signal. The scattering depends on angle (altitude) and the polarization plane of the laser.
Barnes, J., T. Kaplan, H. V�mel and W. G. Read, (2008), NASA/Aura/Microwave Limb Sounder water vapor validation at Mauna Loa Observatory by Raman lidar, Journal of Geophysical Research-Atmospheres, 113, D15, D15S03, doi:10.1029/2007JD008842 Abstract [1] The NASA/Aura/Microwave Limb Sounder (MLS) instrument has been compared to the Mauna Loa Observatory Raman water vapor lidar. Calibration of the lidar used Vaisala RS80-H radiosondes launched from the observatory. The average standard deviation between the sondes and the lidar, in the range 6 km to 11.5 km, is 11.9%. The sondes indicate no overlap correction for the lidar at low altitudes is necessary. A comparison was made between the lidar total column water and a GPS total column water measurement as a check on the calibration, resulting in a correlation slope of 1.026 � 0.058 and R2 = 0.84. The MLS measurements are significantly better in the stratosphere where the lidar has poor sensitivity. The MLS measurement in the troposphere has much lower altitude resolution than the lidar so the validation overlap altitudes are limited. A comparison is made with version 1.5 MLS data for 32 overpasses at the three MLS altitudes in the troposphere. The GPS total column water measurement was used to screen the overpasses by eliminating ones where the water varied by more than 50% during the lidar integration period. At 147 hPa the MLS data show a dry bias of 44.8% � 36%. At 215 hPa the MLS measurement also shows a dry bias of 22.3% � 22%, and at 316 hPa there is a dry bias of 19.9% � 46%. The dry bias seen is consistent with the cryogenic frost point hygrometer (CFH) measurements at many latitudes (23% � 37% at 215 hPa and 4% � 62% at 316 hPa).
Barnes, J. and D. J. Hofmann, (2001), Variability in the stratospheric background aerosol over Mauna Loa Observatory, Geophysical Research Letters, 28, 15, 2895-2898, 2001GL013127 Abstract The stratospheric aerosol layer above Mauna Loa Observatory (MLO), Hawaii, has been at low background levels for the past 5 years. This is the first time that an extended non?volcanic background aerosol period has been observed since modern measurements began in the early 1960s. Lidar backscatter at 532 nm shows a distinct maximum in winter and minimum in summer. The five annual cycles have included three easterly phases and two westerly phases of the quasibiennial oscillation (QBO). Differences in aerosol backscatter versus altitude profiles are seen for different QBO phases. There is also a switching of about 25% in the magnitude of the aerosol backscatter on a weekly time scale with varying particle size derived from multiwavelength data. Assumption of a tropical particle source at background suggests that the differing particle regimes are tropical and midlatitude.
Barnes, J. and D. J. Hofmann, (1997), Lidar measurements of stratospheric aerosol over Mauna Loa Observatory, Geophysical Research Letters, 24, 15, 1923-1926, 97GL01943 Abstract Dual?wavelength aerosol lidar backscatter measurements at Mauna Loa Observatory are used to monitor and characterize the 15�30 km stratospheric aerosol layer. The decay of aerosol loading following the El Chich�n, Mexico (17�N) and Pinatubo, Philippine Islands (15�N) volcanic eruptions of 1982 and 1991, respectively, depends on the phase of the quasibiennial oscillation (QBO) in tropical stratospheric winds. Averaged over a 3?year period, these effects are removed and an exponential decay with a characteristic (e?1) decay time of about 1 year is observed for both eruptions. By the end of 1996, about 5 � years after the Pinatubo eruption, stratospheric aerosol levels at Mauna Loa had decayed to pre?eruption levels, approximately matching the lowest aerosol levels seen here in the past 17 years (about 6 � 10?5 sr?1 at 694 nm integrated between 15.8 and 33 km). However, this background stratospheric aerosol level at Mauna Loa may depend on the QBO, being slightly lower during the westerly phase. Analyses of aerosol backscatter, backscatter wavelength dependence, and trajectories provide evidence for a minor injection of aerosol from the Rabaul eruption in Papua, New Guinea (4�S) in September of 1994.
Barnes, J. E., N. C. Parikh Sharma and T. B. Kaplan, (2007), Atmospheric aerosol profiling with a bistatic imaging lidar system, Applied Optics, 46, 2922-2929, 10.1364/AO.46.002922 Abstract Atmospheric aerosols have been profiled using a simple, imaging, bistatic lidar system. A vertical laser beam is imaged onto a charge-coupled-device camera from the ground to the zenith with a wide-angle lens (CLidar). The altitudes are derived geometrically from the position of the camera and laser with submeter resolution near the ground. The system requires no overlap correction needed in monostatic lidar systems and needs a much smaller dynamic range. Nighttime measurements of both molecular and aerosol scattering were made at Mauna Loa Observatory. The CLidar aerosol total scatter compares very well with a nephelometer measuring at 10 m above the ground. The results build on earlier work that compared purely molecular scattered light to theory, and detail instrument improvements.
Bhattacharya, S.K., Tiwari, Y.K., Masarie, K.A., Langenfelds, R., Krummel, P., Steele, L.P., Allison, C.E., Francey, R.J., Borole, D.V., Patra, P.K., , (2009), Trace gases and CO2 isotope records from Cabo de Rama, India, Current Science, 97, 9, 1336-1344, Abstract Concentrations of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), nitrous oxide (N2O) and hydrogen (H2), and the stable carbon (δ 13C–CO2) and oxygen (δ 18O–CO2) isotopic composition of CO2 have been measured in air samples collected from Cabo de Rama (CRI), India, for the period 1993–2002. The observations show clear signatures of Northern and Southern Hemispheric (NH and SH) air masses, mixed with their regional fluxes and chemical loss mechanisms, resulting in complex seasonal variation of these gases. The CRI measurements are compared with remote marine sites at Seychelles and Mauna Loa. Simulations of two major anthropogenic green- house gases (CO2 and CH4) concentrations using a chemistry-transport model for the CRI site suggest that globally optimized fluxes can produce results comparable to the observations. We discuss that CRI observations have provided critical guidance in opti- mizing the fluxes to constrain the regional source/ sinks balance.
Bodhaine, B., (1996), Aerosol measurements during the Mauna Loa photochemistry experiment 2, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 101, D9, 14757-14765, Paper number 95JD02045 Abstract Aerosol measurements have been made continuously at Mauna Loa Observatory (MLO) from 1974 to the present. Condensation nucleus (CN) concentration has been measured using automatic CN counters, and aerosol scattering extinction (sigma(sp)) has been measured using a four-wavelength nephelometer. The Mauna Loa Observatory Photochemistry Experiment (MLOPEX) was conducted in 1991-1992 to study intensively many important variables in the field of atmospheric chemistry. Because of a strong diurnal cycle in nearly everything measured at MLO caused by an upslope-downslope wind system, it is important to develop data-editing criteria that can safely identify background conditions as opposed to other conditions when the site may be contaminated by local sources. Ordinarily, background conditions occur during nighttime downslope wind conditions, and contaminated conditions occur during daytime upslope wind conditions. However, occasionally unusual weather conditions or contamination caused by a local source such as the Mauna Loa caldera can confuse the issue. It is recommended that background aerosol data be chosen during 0000-0800 Hawaiian standard time (HST) to generally avoid upslope wind conditions, and that wind direction and speed, CN, and SO2 data be used if available to further eliminate local pollution episodes. In addition, all data should be examined by a human editor, if possible, in order to recognize certain episodes that may not fit automated criteria.
Bodhaine, B.A., (1995), Aerosol absorption measurements at Barrow, Mauna Loa and the south pole, Journal of Geophysical Research-Atmospheres, 100, D5, 8967-8975, 95JD00513 Abstract Aerosol absorption (?ap) has been measured continuously using aethalometers at Barrow, Alaska (1986 to present); Mauna Loa, Hawaii (1990 to present); and south pole, Antarctica (1987�1990). These three stations are part of a network of baseline monitoring stations operated by the Climate Monitoring and Diagnostics Laboratory (CMDL) of the National Oceanic and Atmospheric Administration (NOAA). Condensation nucleus (CN) concentration and multiwavelength aerosol scattering (?sp) have also been measured continuously for many years at these stations. Aethalometer measurements are usually reported in terms of atmospheric black carbon aerosol (BC) concentration using the calibration suggested by the manufacturer. Here we deduce the in situ ?ap(550 nm) from aethalometer measurements by assuming that the aerosol absorption on the aethalometer filter is enhanced by a factor of 1.9 over that in the atmosphere. This is consistent with using 19 m2 g?1 for the specific absorption of BC on the aethalometer filter and 10 m2 g?1 for the in situ specific absorption of BC in the atmosphere (the ratio of the two specific absorptions is 1.9). Although these values of specific absorption may vary significantly for different environments, the ratio might be expected to be relatively constant. The single-scattering albedo, defined by ? = ?sp/(?sp + ?ap), has been estimated from the simultaneous measurements of ?ap and ?sp. Furthermore, assuming a 1/? dependence for ?ap in the 450 to 700-nm wavelength region, multiwavelength ?sp measurements allow the estimation of the wavelength dependence of ?. Each station shows a considerable annual cycle in ?ap, ?sp, and ?. The maximum in the Barrow annual cycle is caused primarily by the springtime Arctic haze phenomenon; the maximum in the Mauna Loa annual cycle is caused by the springtime Asian dust transport; and the maximum in the south pole annual cycle is caused by late winter transport from southern midlatitudes. It was found that annual mean values are ?ap = 4.1 � 10?7 m?1 (?41 ng m?3 BC) and ? = 0.96 for Barrow; ?ap = 5.8 � 10?8 m?1 (?5.8 ng m?3 BC) and ? = 0.97 for Mauna Loa; and ?ap = 6.5 � 10 ?9 m?1 (?0.65 ng m?3 BC) and ? = 0.97 for south pole. It was also found that the wavelength dependence of ? may be important at Barrow and south pole, but not important at Mauna Loa.
Bodhaine, B. A., (1983), Aerosol measurements at four background sites, Journal of Geophysical Research, 88, C15, 10753-10768, 10.1029/JC088iC15p10753 Abstract Atmospheric monitoring stations are operated at Barrow, Alaska; Mauna Loa, Hawaii; American Samoa; and South Pole by the Geophysical Monitoring for Climatic Change program to measure the characteristics of gaseous and aerosol species under background conditions. A nearly continuous record of light-scattering coefficient and condensation nuclei concentration measurements is available for Barrow since 1971, Mauna Loa since 1974, Samoa since 1977, and South Pole since 1974. The Barrow light-scattering data exhibit a strong annual cycle with a maximum in winter and spring (the Arctic haze) and a minimum in summer. The Barrow condensation nuclei data exhibit a strong semiannual cycle with a maximum coinciding with that of light scattering and an additional maximum about August. The Mauna Loa light-scattering data show a strong annual cycle with a maximum in April or May caused by long-range transport of Asian desert dust. The Mauna Loa condensation nuclei data show no significant annual cycle. The Samoa light-scattering and condensation nuclei data are representative of a clean marine atmosphere and exhibit no significant annual or diurnal cycle. The South Pole light-scattering data show a complicated annual cycle with a maximum in the austral summer and a minimum about April. The austral winter is dominated by events most likely caused by the transport of sea salt in the troposphere from the coastal regions to the interior of the Antarctic continent. The South Pole condensation nuclei data show a repeatable annual cycle with a maximum in the austral summer and a minimum in the austral winter. Linear least squares trend analyses show no significant trend compared to the standard error about the regression line at any station.
Bodhaine, B. A., B. G. Mendonca, J. M. Harris and J. M. Miller, (1981), Seasonal variations in aerosols and atmospheric transmission at Mauna Loa Observatory, Journal of Geophysical Research Oceans, 86, C8, 7395-7398, 10.1029/JC086iC08p07395 Abstract Aerosol light scattering and atmospheric transmission data taken at Mauna Loa Observatory show seasonal variations that are strongly correlated and in phase. Total ozone above Mauna Loa is also in phase but accounts for only about 20% of the seasonal variation in atmospheric transmission while aerosols account for the other 80%. Total precipitable water vapor above Mauna Loa is out of phase with atmospheric transmission and cannot account for its seasonal variation. Long-range atmospheric trajectory analyses indicate that tropospheric transport of aerosols from the direction of the Asian continent is most likely responsible for the seasonal variations in atmospheric transmission and aerosol optical properties.
Bodhaine, B. A., E. G. Dutton, D. J. Hofmann, R. L. McKenzie and P. Johnston, (1997), UV measurements at Mauna Loa: July 1995 to July 1996, Journal of Geophysical Research-Atmospheres, 102, D15, 19265-19273, 97JD01391 Abstract A UV spectroradiometer was installed at Mauna Loa Observatory (MLO), Hawaii, in July 1995. This instrument, based on a commercially available double monochromator, uses a diffuser mounted as a horizontal receptor inside a quartz dome and views the whole sky. The instrument scans over the 290�450 nm spectral range with a band pass of about 1 nm for each 5� of solar zenith angle (SZA). The UV irradiances measured at MLO are much more intense than at low-altitude midlatitude locations. For observations at SZA 45� the erythemally weighted UV irradiances can exceed 21 ?W cm?2, which is approximately 15�20% greater than that seen at Lauder, New Zealand, for similar ozone amounts. The difference is primarily due to the higher altitude at MLO (3.4 km). For overhead Sun conditions at MLO the largest value of erythemal UV was 51.3 � 3.1 ?W cm?2, which to our knowledge is the highest recorded any-where at the Earth's surface. UV irradiance is strongly correlated (inversely) with Dobson spectrophotometer total ozone measurements at MLO, with higher correlations at shorter wavelengths. The radiative amplification factor (RAF) for erythema at MLO is about 1.33 � 0.2 at SZA 45�.
Bodhaine, B. A., E. G. Dutton, R. L. McKenzie and P. V. Johnston, (1998), Calibrating Broadband UV Instruments: Ozone and Solar Zenith Angle Dependence, Journal of Atmospheric and Oceanic Technology, 15, 4, 916-926, doi:10.1175/1520-0426(1998)015<0916:CBUIOA>2.0.CO;2 Abstract A UV spectroradiometer was installed at Mauna Loa Observatory (MLO), Hawaii, in July 1995. This instrument has been employed to characterize several broadband UV instruments of a type commonly used to estimate erythemal irradiance at many sites around the globe. One year of clear-sky data from MLO has been analyzed for solar zenith angles (SZAs) of 5��85�, in steps of 5�, and for total ozone values in the range 220�310 DU measured with a Dobson spectrophotometer. Because the spectral responses of various broadband instruments can be quite different, and particularly because the erythemal response defined for human skin is significantly different than that of many broadband instruments, the calibration of a broadband instrument reporting in erythemal units is strongly dependent on total ozone and SZA. When a broadband instrument is placed in the field it is necessary to know the calibration as a function of ozone and SZA to determine accurate erythemal irradiance. However, the manufacturers of broadband instruments do not generally provide information on the ozone dependence of the calibration. A procedure is described here for determining the calibration of a broadband UV instrument by comparison with a calibrated spectroradiometer. This procedure does not require precise knowledge of the spectral response of the broadband instrument. This analysis shows that if, for example, total ozone concentration decreased from 300 to 200 DU, the calibration constant of a broadband instrument should be increased by almost 20%. Therefore, the broadband instrument would significantly underestimate the increase of erythema.
Bodhaine, B.A., J. M. Harris, G.A. Herbert and W.D. Komhyr, (1980), Identification of Volcanic Episodes in Aerosol Data at Mauna Loa Observatory, Journal of Geophysical Research-Oceans, 85, c3, 1600-1604, doi:10.1029/JC085iC03p01600 Abstract Measurements of background atmospheric constituents at Mauna Loa Observatory, Hawaii, are occasionally subject to contamination by local effects such as upslope wind flow or volcanic emissions from Mauna Loa volcano. Volcanic episodes have been identified during 1978 with a sulfur dioxide meter operated at the observatory. In combination with surface wind data these SO2 measurements have been used to examine aerosol data, taken at the observatory, for volcanic episodes and to develop criteria to be used for screening other data taken at the observatory when SO2 measurements are not available. It is found that a requirement that Aitken nuclei concentration be less than about 840 cm?3 will eliminate only about 2% of the data during southerly wind conditions and still approximate the background conditions determined by independently removing known volcanic episodes.
Bodhaine, B. A., Joyce M. Harris, J. A. Ogren and David J. Hofmann, (1992), Aerosol optical properties at Mauna Loa Observatory: Long-range transport from Kuwait?, Geophysical Research Letters, 19, 6, 581-584, Paper Number: 92GL00524 Abstract Aerosol light absorption has been measured continuously at Mauna Loa Observatory, Hawaii (MLO), since April 1990. During the spring of 1991, after oil wells were fired in Kuwait, there was speculation among scientists concerning long-range transport of smoke particles and its possible effect on global climate. The MLO light absorption record from April 1990 to June 1991 shows low values in the 0.1-1 x 10(-7) m-1 range in the summer of 1990, and an increased baseline level of about 2-4 x 10(-7) m-1 with numerous superimposed events in the 5-10 x 10(-7) m-1 range in the spring of 1991. These levels correspond to black carbon (BC) concentrations of 1-10, 20-40, and 50-100 ng m-3, respectively, under the assumption that BC is the dominant light absorbing species and has a specific absorption of 10 m2 g-1. Large-scale 500-hPa trajectories calculated backwards from MLO sometimes show direct transport paths from China and Kuwait to Hawaii that coincide with the black carbon events. These measurements set an upper limit on the possible contribution of Kuwaiti black carbon to the background troposphere near MLO during periods of rapid transport. The aerosol observed at MLO is expected to cause a net cooling of the atmosphere.
Bodhaine, B.A., R.L. McKenzie, P.V. Johnston, D. J. Hofmann, E. G. Dutton, R. C. Schnell, J. Barnes, S. Ryan and M. Kotkamp, (1996), New Ultraviolet Spectroradiometer measurements at Mauna Loa Observatory, Geophysical Research Letters, 23, 16, 2121-2124, GL01954 Abstract A research?grade scanning UV spectroradiometer was installed at Mauna Loa Observatory (MLO), Hawaii, in July 1995. This instrument, built around a commercially available double monochromator, is interfaced with a PC to provide automatic control and data acquisition. The spectral range sampled by the instrument is 290�450 nm, and the bandpass is about 1 nm. A complete scan requires about 200 seconds and is performed every 5 degrees of solar zenith angle (SZA) during daylight hours. Calibration is performed on site at 6?month intervals using a 1000?W standard quartz?halogen FEL lamp with calibration traceable to NIST. The UV irradiances measured at MLO are much more intense than at low altitude mid?latitude locations. For observations at a SZA of 45�, the erythemally weighted UV can exceed 18 ?W cm?2, which is approximately 15-20% greater than the maxima seen at Lauder, NeW Zealand, for similar ozone amounts. The difference is primarily due to the higher altitude at MLO. For overhead sun conditions at MLO, erythemal UV can exceed 45 ?W cm?2, which to our knowledge is the highest recorded anywhere at the Earth's surface. UV irradiance is strongly correlated (inversely) with Dobson spectrophotometer total ozone measurements at MLO, with higher correlations at shorter wavelengths. The radiative amplification factor (RAF) for erythema at MLO is about 1.44�0.46 at SZA 45�. Using ozone retrievals from the UV spectra themselves, the deduced RAF for erythema is 1.26�0.38. The RAFs for erythema at SZA 60� are similar, and in agreement with other determinations within the limits of experimental uncertainty.
Bodhaine, B.A. and B. Mendonca, (1974), Preliminary four wavelength nephelometer measurements at Mauna Loa Observatory, Geophysical Research Letters, 1, 3, 119-122, doi:10.1029/GL001i003p00119 Abstract A 4? nephelometer has been included as part of the aerosol monitoring program at Mauna Loa Observatory, Hawaii. This instrument is capable of measuring the clean air (nighttime downslope wind conditions) aerosol light scattering coefficient of bsp ? 3 � 10?7m?1, about 1% of the molecular scattering of air. Typical light scattering values for �dirty� (upslope wind) conditions are of the order of bsp ? 5 � 10?5m?1. Although rare, vigorous fountaining at Kilauea Volcano occasionally ejects particulate into the upper air and encroaches upon the clean air at Mauna Loa. However, volcanism does not interfere significantly with the background monitoring program. The aerosol size information obtained from the 4? nephelometer functions as an indicator of the aerosol source and therefore of possible global trends in aerosol size or concentration.
Bodhaine, B.A. and R.F. Pueschel, (1974), Source of Seasonal Variations in Solar Radiation at Mauna Loa, Journal of the Atmospheric Sciences, 31, 3, 840-845, doi:10.1175/1520-0469(1974)031<0840:SOSVIS>2.0.CO;2 Abstract Solar radiation transmission data taken at Mauna Loa exhibit a seasonal variation with the minimum in summer. On the basis of Barrett's model for the depletion of solar radiation by aerosols, it is suggested that these variations are due to the seasonal generation of organic aerosols by the biosphere. It is suggested that the naturally produced atmospheric background aerosol of organic origin causes the typical seasonal turbidity variations. Furthermore, changes in the amplitude or phase of transmission data could be used to indicate whether aerosols from anthropogenic sources would influence the earth's albedo. Precipitable water calculations suggest that humidity data above Mauna Loa are not accurate enough to make a quantitative estimate of the effect of atmospheric water vapor on Mauna Loa radiation data. However, water vapor apparently cannot account for these variations on the basis of phase angle considerations.
Bodhaine, B.A. and R.F. Pueschel, (1972), Flame Photometric Analysis of the Transport of Sea Salt Particles, Journal of Geophysical Research-Oceans, 77, 27, 5106-5115, doi:10.1029/JC077i027p05106 Abstract The method of flame scintillation spectral analysis has been adopted for the determination of the size distribution of sodium-containing particles. Near the seashore, these aerosols are identical to sea salt particles, amount to approximately 5% of the total Aitken particle count, and exhibit a power law distribution with β = 3.8. Measurements made at Mauna Loa Observatory (above the trade wind inversion) indicate a smaller size distribution. However, only about 1% of the concentration is transported through the inversion, and removal efficiency tends to favor the removal of larger particles.
C
Conway, T. J. and P. P. Tans, (1999), Development of the CO2 Latitude Gradient in Recent Decades, Global Biogeochemical Cycles, 13, 4, 821-826, 1999GB900045 Abstract Because 90% of the CO2 from fossil fuel combustion is emitted in the Northern Hemisphere, annual mean atmospheric CO2 mixing ratios are higher at middle and high northern latitudes than in the Southern Hemisphere. The observed CO2 latitude gradient varies interannually and has generally increased as fossil fuel CO2 emissions have increased. Back extrapolation of the measured CO2 latitude gradient to zero fossil fuel emissions gives a latitude gradient with the Northern Hemisphere lower than the Southern. A linear regression of Mauna Loa minus South Pole annual mean differences versus fossil fuel emissions for 1958 through 1996 gives a slope of 0.5 ?mol mol?1 (abbreviated as ppm CO2) (Gt C)?1 (? = 0.03) and an intercept (at zero fossil fuel emissions) of ?0.8 ppm (? = 0.2). Shorter data records yield similar results with larger uncertainties. We argue that this extrapolated gradient does not represent preindustrial conditions but is more correctly viewed as a decadal average gradient due to natural sources and sinks that underlie the anthropogenic perturbation. We interpret the extrapolated gradient as evidence for a contemporary Northern Hemisphere sink that has been proposed on the basis of other measurement and model approaches. The slopes (ppm CO2 per gigaton of C from fossil fuel burning) calculated from sufficiently long records tend to agree with model calculations based on fossil fuel emissions, suggesting that any trend in the Northern Hemisphere sink, during the period of the measurements, has been small relative to the trend in fossil fuel emissions.
Cooper, O. R., Andreas Stohl, G. H�bler, E. Y. Hsie, D. D. Parrish, A. F. Tuck, G. N. Kiladis, S. J. Oltmans, B. J. Johnson, M Shapiro, J. Moody and A. Lefohn, (2005), Direct transport of midlatitude stratospheric ozone into the lower troposphere and marine boundary layer of the tropical Pacific Ocean, JGR-Atmospheres, 110, D23, , doi:10.1029/2005JD005783 Abstract The detailed survey of midlatitude stratospheric intrusions penetrating into the Northern Hemisphere tropics was one goal of the Pacific Sub-Tropical Jet Study 2004, conducted from Honolulu, Hawaii, during 19-29 January and 28 February to 15 March. Using the National Oceanic and Atmospheric Administration G-IV jet aircraft, instrumented with dropsondes and a 1-s resolution ozone instrument, we targeted an intrusion above Hawaii on 29 February. The data describe the strongest tropospheric ozone enhancements ever measured above Hawaii (in comparison to a 22 year ozonesonde record) and illustrate the mixing of stratospheric ozone into the midtroposphere as a result of convection triggered by the advection of relatively cold midlatitude air into the tropics. Measurements from the G-IV and Mauna Loa Observatory (3.4 km) show enhanced ozone in the lower troposphere, indicating that the remnants of the intrusion reached these levels. This conclusion is supported by a study using a stratospheric ozone tracer generated by the FLEXPART Lagrangian particle dispersion model. This paper also describes a similar intrusion that enhanced ozone at Mauna Loa on 10 March, as well as Honolulu, which is located in the marine boundary layer. G-IV flights in and out of Honolulu measured enhanced ozone associated with this event on several occasions. The 10 March event transported an estimated 1.75 Tg of ozone into the tropical troposphere, and we suggest that stratospheric intrusions that break away from the polar jet stream as they advect into the tropics are more effective at transporting ozone into the troposphere than intrusions that remain close to the polar jet stream in midlatitudes. Analysis of the dynamic conditions indicates that the frequency of stratospheric intrusions was not anomalous during January-March 2004. While the 10 March event was by itself an extreme event, strong stratospheric intrusions can be expected to influence the tropical lower troposphere in any year.
Coulson, K. L., (1981), Characteristics of skylight at the zenith during twilight as indicators of atmospheric turbidity: Part 2, Intensity and color ratio, Applied Optics, 20, 9, 1516-1524, 10.1364/AO.20.001516 Abstract This is the second of two papers based on an extensive series of measurements of the intensity and polarization of light from the zenith sky during periods of twilight made at an altitude of 3400 m on the island of Hawaii. Part 1 dealt with the skylight polarization; part 2 is on the measured intensity and quantities derived from the intensity. The principal results are that (1) the polarization and intensity of light from the zenith during twilight are sensitive indicators of the existence of turbid layers in the stratosphere and upper troposphere, and (2) at least at Mauna Loa primary scattering of the sunlight incident on the upper atmosphere during twilight is strongly dominant over secondary or multiple scattering at wavelengths beyond ~0.60�m, whereas this is much less true at shorter wavelengths. It is suggested that the development and general use of a simple twilight polarimeter would greatly facilitate determinations of turbidity in the upper layers of the atmosphere.
D
DeFoor, T.E., E. Robinson and S. Ryan, (1992), Early lidar observations of the June 1991 Pinatubo eruption plume at Mauna Loa Observatory, Hawaii, Geophysical Research Letters, 19, 2, 187-190, 91GL02791 Abstract The June 1991 eruption of the Philippine volcano Pinatubo introduced a massive plume of volcanic ash and other aerosol material into a stratosphere containing only near?background concentrations of aerosol material. At Mauna Loa Observatory, Hawaii, the Pinatubo plume was first observed by lidar on 1 July 1991. During July and August the observable effects from this plume increased in intensity in terms of aerosol optical properties, plume height, and broad band solar radiation. Preliminary data analysis shows that the plume over Hawaii arrived in three generalized pulses or waves on approximately 3 July, 24 July, and 9 August. There was a decrease of about 13% in a broad band atmospheric transmission factor over Hawaii between June 1991 and Pinatubo affected conditions on 31 August 1991. At the end of August 1991, the Pinatubo plume over Hawaii exhibited characteristics similar in magnitude to what was observed at Mauna Loa after the El Chichon eruption in 1982. However, the early Pinatubo maximum plume heights were lower than were observed in the early months of the El Chichon plume dispersion. The Pinatubo plume was continuing to increase in magnitude and height at MLO at the end of August.
DeFoor, T. E. and E. Robinson, (1987), Stratospheric lidar profiles from Mauna Loa Observatory, Winter 1985-1986, Geophysical Research Letters, 14, 6, 618-621, 10.1029/GL014i006p00618 Abstract In the period from mid?November 1985 through April 1986 the stratospheric aerosol profiles determined by lidar observations at the Mauna Loa, Hawaii Observatory indicated a persistent sequence of profiles characteristic of stratospheric volcanic aerosols. Aerosol layers were observed in two general altitude ranges. A high layer between about 25 and 27 km was detected in late November 1985 and again in late February and late March 1986. A lower layer, generally located between 20 and 23 km was present from early December 1985 through April 1986. These layers appear to have been due to the November 13, 1985 eruption of Nevado del Ruiz in Columbia. On the basis of these lidar data the impact of this volcanic plume on direct solar irradiance at 694 nm in Hawaii was estimated to have been an average diminution of about 0.4 per cent during the period December 1985 through April 1986.
Deluisi, J., B. Mendonca and K.J. Hanson, (1980), Measurements of stratospheric aerosols over Mauna Loa, Hawaii and Boulder, Colorado, Mount St. Helens' Eruption: Its Atmospheric Effects and Potential Climatic Impact Symposium, November 18-19, 1980, Washington, D. C. Abstract The direct solar radiation transmission record at Mauna Loa, dating from 1958 to the present, revealed with remarkable precision the presence of stratospheric aerosol from volcanic activity. This record can be used to quantify the intensity of the stratospheric volcanic aerosol perturbation following a significant eruption in reference to the Agung event in 1963. The Mount St. Helens' stratospheric cloud was first detected by lidar at 18 km over Mauna Loa on 17 July. The atmospheric transmission was seen to decrease slightly after that time, but only a few tenths of 1 percent. Although it is still fairly early to draw a definite conclusion on the ultimate magnitude of the Mount St. Helens stratospheric aerosol from the Mauna Loa results, it can be stated that the stratospheric aerosol optical depth presently observed is comparable with that observed from Fuego which erupted in 1974. At Boulder, Colorado, the atmospheric debris from Mount St. Helens was observed by lidar on a number of occasions. Also, observations of the diffuse, total and direct transmission of solar radiation were made on June 3 and 4. The latter set of observations is useful for deriving information on the scattering properties of the volcanic cloud. The lidar and solar radiation data are presented and some of their special features are discussed.
Deluisi, J., E. G. Dutton, K. L. Coulson, T. E. DeFoor and B. G. Mendonca, (1983), On some radiative features of the El Chichon volcanic stratospheric dust cloud and a cloud of unknown origin observed at Mauna Loa, Journal of Geophysical Research, 88, C11, 6769-6772, 10.1029/JC088iC11p06769 Abstract We present some results of our initial optical observations of the El Chichon volcanic cloud. These observations were made at the Geophysical Monitoring for Climatic Change Mauna Loa Observatory, Hawaii, and consist of lidar profiles, optical thickness, spectral variation in optical thickness and changes in global and direct solar broadband fluxes. Particle size distribution and cloud mass information contained in the optical thickness observations are discussed. It is clear that the atmospheric radiative effects of the El Chichon cloud far exceed the effects of all other volcanic clouds observed at Mauna Loa since observations were begun in 1958.
Deluisi, J., E. G. Dutton, K. L. Coulson, T. E. DeFoor and B. Mendonca, (1983), On some radiative features of the El Chich�n volcanic stratospheric dust cloud and a cloud of unknown origin observed at Mauna Loa, Journal of Geophysical Research-Oceans, 88, C11, 6769-6772, 3C0814 Abstract We present some results of our initial optical observations of the El Chichon volcanic cloud. These observations were made at the Geophysical Monitoring for Climatic Change Mauna Loa Observatory, Hawaii, and consist of lidar profiles, optical thickness, spectral variation in optical thickness and changes in global and direct solar broadband fluxes. Particle size distribution and cloud mass information contained in the optical thickness observations are discussed. It is clear that the atmospheric radiative effects of the El Chichon cloud far exceed the effects of all other volcanic clouds observed at Mauna Loa since observations were begun in 1958.
Deshler, T, R Anderson-Sprecher, H Jager, J. Barnes, D. Hofmann, B Clemesha, D Simonich, M Osborn, R. Grainger and S Godin-Beekmann, (2006), Trends in the nonvolcanic component of stratospheric aerosol over the period 1971-2004, Journal of Geophysical Research-Atmospheres, 111, D1, , doi:10.1029/2005JD006089 Abstract [1] The six longest records of stratospheric aerosol ( in situ measurements at Laramie, Wyoming, lidar records at: Garmisch-Partenkirchen, Germany; Hampton, Virginia; Mauna Loa, Hawaii; Sao Jose dos Campos, Brazil, and SAGE II measurements) were investigated for trend by ( 1) comparing measurements in the 3 volcanically quiescent periods since 1970 using standard analysis of variance techniques, and ( 2) analyzing residuals from a time/volcano dependent empirical model applied to entire data sets. A standard squared-error residual minimization technique was used to estimate optimum parameters for each measurement set, allowing for first order autocorrelation, which increases standard errors of trends but does not change magnitude. Analysis of variance over the 3 volcanically quiescent periods is controlled by the end points (pre-El Chichon and post-Pinatubo), and indicates either no change (Garmisch, Hampton, Sao Jose dos Campos, Laramie-0.15 mu m) or a slight, statistically insignificant, decrease ( Mauna Loa, Laramie-0.25 mu m), - 1 +/- 0.5% yr(-1). The empirical model was applied to the same records plus 1020 nm SAGE II data separated into 33 latitude/altitude bins. No trend in stratospheric aerosol was apparent for 31 of 33 SAGE II data sets, 3 of 4 lidar records, and in situ measurements at 0.15 mu m. For Hampton and Laramie-0.25 mu m, the results suggest a weak negative trend, - 2 +/- 0.5% yr(-1), while 2 SAGE II data sets ( 30 - 35 km, 30 degrees and 40 degrees N) suggest a positive trend of similar magnitude. Overall we conclude that no long-term change in background stratospheric aerosol has occurred over the period 1970 - 2004.
Dlugokencky, E. J., L. P. Steele, P. M. Lang and K. A. Masarie, (1995), Atmospheric methane at Mauna Loa and Barrow observatories: Presentation and analysis of in situ measurements, Journal of Geophysical Research-Atmospheres, 100, d11, 23103-23113, doi:10.1029/95JD02460 Abstract In situ methane (CH4) measurement techniques and data from the NOAA Climate Monitoring and Diagnostics Laboratory observatories at Mauna Loa, Hawaii, and Barrow, Alaska, are presented. For Mauna Loa, the data span the time period April 1987 to April 1994. At Barrow the measurements cover the period January 1986 to January 1994. Sixty air samples per day were measured with a fully automated gas chromatograph using flame ionization detection. Details of the experimental methods and procedures are given. Data are presented and assessed over various timescales. The average peak to peak seasonal cycle amplitudes obtained from four harmonics fitted to the detrended data were 25.1 ppb at Mauna Loa and 47.2 ppb at Barrow. When the seasonal cycle amplitude during each calendar year was determined as the difference between the maximum and minimum value from a smooth curve fitted to the data, the average amplitudes were (30.6 �4.2) ppb at Mauna Loa and (57.5 � 11.4) ppb at Barrow. A discrepancy exists between these two methods due to the temporal variability in the positions of the seasonal maxima. The average trend at Mauna Loa was 9.7 ppb yr?1, but this trend was observed to decrease at a rate of 1.5 ppb yr?2. For Barrow the average trend was 8.5 ppb yr?1, and the rate of decrease in the trend was 2.1 ppb yr?2. At Mauna Loa, a diurnal cycle was sometimes observed with an amplitude of up to 10 ppb when averaged over 1 month.
Dutton, E. G., (1992), A coherence between the QBO and the amplitude of the Mauna Loa atmospheric transmission annual cycle, INTERNATIONAL JOURNAL OF CLIMATOLOGY, 12, 4, 383-396, doi:10.1002/joc.3370120406 Abstract The transmission of direct solar radiation through the atmosphere above Mauna Loa, Hawaii, is shown to have a quasi-biennial cyclic component that is coherent with the well-known tropical stratospheric quasi-biennial oscillation (QBO). The QBO-related signal in the 32-year transmission record is manifested as an oscillation in the amplitude of the annual cycle. The transmission annual cycle is known to be caused by seasonal transport of Asian continental dust to and over the island of Hawaii. Variations in water vapour and ozone are eliminated as possible influences in the transmission-QBO relationship, leaving aerosols as the source of the oscillation. The ultimate cause for the quasi-biennial signal in the transmission record is unknown. Small but cyclic modifications to the tropospheric energy budget occur as a result of the transmission variations. The magnitude of the energy budget variations are less than those typically expected to have a significant climatic impact.
Dutton, E. G., (1991), A coherence between the QBO and the amplitude of the Mauna Loa atmospheric transmission annual cycle, IUGG/IAMAP Bi-Annual Meeting, August 11-14, 1991, Vienna, Austria Abstract The transmission of direct solar radiation through the atmosphere above Mauna Loa, Hawaii, is shown to have a quasi-biennial cyclic component that is coherent with the well-known tropical stratospheric quasi-biennial oscillation (QBO). The QBO-related signal in the 32-year transmission record is manifested as an oscillation in the amplitude of the annual cycle. The transmission annual cycle is known to be caused by seasonal transport of Asian continental dust to and over the island of Hawaii.
Dutton, E. G., J. Deluisi and A. P. Austring, (1985), Interpretation of Mauna Loa atmospheric transmission relative to aerosols, using photometric precipitable water amouts, Journal of Atmospheric Chemistry, 3, 1, 53, doi:10.1007/BF00049368 Abstract Precipitable water measurements made coincident in time and space with direct broadband solar irradiance measurements are used in conjunction with an atmospheric transmission model to derive a parameter whose major dependence is on total aerosol extinction. Irradiance measurements are used to calculate an atmospheric transmission factor (ATF) that is independent of the instrument calibration and the extraterrestrial solar constant. The dependency of the ATF on precipitable water is determined using LOWTRAN5, an atmospheric transmission model with high spectral resolution. Precipitable water measurements are then used to adjust the measured ATF to correspond to an ATF value obtained for a constant precipitable water amount. The remaining variability in the adjusted ATF is due mostly to aerosol extinction. The technique is applied to a 6-year period (1978�1983) for clear-sky mornings at Mauna Loa, Hawaii (MLO). MLO ATF aerosol residuals are compared with independently measured monochromatic aerosol optical depth. Results show that the ATF aerosol residual is nearly equal to the 500 nm aerosol optical depth prior to the eruption of E1 Chichon, at which time a nonlinear time-dependent relationship between the two quantities is evident. ATF aerosol residuals reflect the spectrally integrated aerosol influence on transmission and, therefore, could indicate better than monochromatic optical depth the radiation balance perturbations due to aerosols. The 6-year precipitable water record for MLO, determined from a dual-channel sunphotometer, has a mean value of 0.3 cm. An annual cycle in precipitable water is evident, as is a 4-month 5-standard-deviation ldquodroughtrdquo from December 1982 through March 1983.
Dutton, E. G., P. Reddy, S. Ryan and J. Deluisi, (1994), Features and effects of optical depth observed at Mauna Loa, Hawaii: 1982-1992, Journal of Geophysical Research-Atmospheres, 99, D4, 8295-8306, 93JD03520 Abstract Spectral aerosol optical depth, ? a , observed at Mauna Loa, Hawaii, for the past 11 years is analyzed for background variations and the effects of two major volcanic eruptions: El Chich�n in 1982 and Mount Pinatubo in 1991. A previously known annual variation and near-background levels are present in the record. The data are of high accuracy, being primarily obtained from an automatic precision sunphotometer and reduced using the Langley-plot slope method. The ? a values over Mauna Loa were greater immediately after the eruption of El Chich�n than after Mount Pinatubo due to more direct transport from El Chich�n. However, Pinatubo had a greater temporally integrated impact because of greater erupted sulfur mass. A mean solar irradiance decrease of 6.5 (�2.5) W m?2 per 0.1 ? a (500 nm) averaged over 24 hours is observed for both volcanic eruptions. Slight differences are suggested between the eruptions, but the differences are not statistically significant. Small differences between the two eruptions in the aerosol size distributions derived from ? a observations are also indicated and are consistent with the suggested difference in total solar irradiance aerosol sensitivity. The near-background ? a values compare well with in situ surface-based aerosol light-scattering measurements extrapolated through the upper troposphere.
Dutton, E. G. and B. A. Bodhaine, (2001), Solar Irradiance Anomalies Caused by Clear-Sky Transmission Variations above Mauna Loa: 1958-99, Journal of Climate, 14, 15, 3255-3262, http://ams.allenpress.com/archive/1520-0442/14/15/pdf/i1520-0442-14-15-3255.pdf Abstract The clear-sky transmission of the atmosphere contributes to determining the amount of solar irradiance that reaches various levels in the atmosphere, which in turn is fundamental to defining the climate of the earth. As of the end of 1999, sustained clear-sky solar transmission over the mid-Pacific, as viewed from Mauna Loa, Hawaii, reached its highest level of clarity since before the eruption of Mount Pinatubo in 1991 and appears to be continuing to increase toward baseline levels established during 1958�62 and not sustained since. This record is used to answer the question as to impact of transmission variations, which can be attributed to either upward scattering or absorption above the station, on the net solar irradiance at 3.4 km, the altitude of the isolated mountain-top observing site. Net solar irradiance at a given level describes the total solar irradiance absorbed below that level. Monthly mean net solar anomalies caused by transmission variations, relative to the 1958�62 baseline, range from ?14 to 2 W m?2 and averaged ?1.45 W m?2 (?0.7%) between 1963 and 1999. Because of inherent attributes of this transmission record, the observed fluctuations in the record are of unusually high precision over the entire period of record and are also representative of an extended surrounding region. Irradiance anomalies have a long-term precision of better than 0.1 W m?2 (?0.05%) per decade. Any possible linear trend for the entire 42 yr is limited by the data to between about 0.0 and ?0.1 W m?2 decade?1, or any net shift over the 42 yr must be in the range of about 0.0 to ?0.35 W m?2 (0.0% to ?0.15%). The transmission fluctuations are potentially caused by various atmospheric constituents, primarily aerosols, ozone, and water vapor, but the role of a specific constituent cannot be uniquely isolated on the basis of the transmission record alone. Aerosols have the greatest potential influence on the record and in general have the ability to cause both scattering and absorption such that the net radiative heating effect in the entire atmospheric column cannot be determined from the transmission data alone. However, because the largest anomalies in the record are known to be due to volcanic eruptions that produce predominantly conservative scattering aerosols, those large anomalies resulted in net radiative cooling tendencies in the entire associated atmospheric column.
Dutton, E. G. and J. R. Christy, (1992), Solar Radiative Forcing at Selected Locations and Evidence for Global Lower Tropospheric Cooling Following the Eruptions of El Chich�n and Pinatubo, Geophysical Research Letters, 19, 23, 2313-2316, 92GL02495 Abstract As a result of the eruption of Mt. Pinatubo (June 1991), direct solar radiation was observed to decrease by as much as 25�30% at four remote locations widely distributed in latitude. The average total aerosol optical depth for the first 10 months after the Pinatubo eruption at those sites is 1.7 times greater than that observed following the 1982 eruption of El Chich�n. Monthly?mean clear?sky total solar irradiance at Mauna Loa, Hawaii, decreased by as much as 5% and averaged 2.4% and 2.7% in the first 10 months after the El Chich�n and Pinatubo eruptions, respectively. By September 1992 the global and northern hemispheric lower tropospheric temperatures had decreased 0.5�C and 0.7�C, respectively compared to pre?Pinatubo levels. The temperature record examined consists of globally uniform observations from satellite microwave sounding units.
E
Elliott, W. P., J. K. Angell and K. W. Thoning, (1991), Relation of atmospheric CO2 to tropical sea and air temperatures and precipitation, Tellus B, 43B, 2, 144-155, 10.1034/j.1600-0889.1991.00009.x Abstract Associations between the season-to-season changes in CO2 concentration and the sea-surface temperature in the eastern equatorial Pacific, the tropospheric air temperature, and the precipitation in the tropics are explored. The CO2 records at Mauna Loa and the South Pole from the Scripps Institution of Oceanography and the GMCC/NOAA program, as well as the GMCC records at Barrow, Alaska and American Samoa were used after the annual cycle and the growth due to fossil fuel emission has been removed. We find that the correlation between CO2 changes and each of the other variables changes with time. In particular, the period from about 1968 to about 1978 was the period of highest correlation, which was also the period when the climate variables were best correlated with each other. The air temperature and the precipitation were as well correlated with CO2 changes as was SST. Also, there are individual seasons when the CO2 changes are much better correlated with the climate variables than at other seasons. Furthermore, El Ni�o events, while the source of the largest signal in the CO2 record, are by no means the same from one event to the next. We take these results as further confirmation that the apparent effect of SST on the CO2 record comes less from changes in the equatorial eastern Pacific Ocean than from climate changes throughout the globe. Climate effects on the terrestrial biosphere seem a likely source of much of the interannual variation in atmospheric CO2.
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Fegley, R.W. and H.T. Ellis, (1975), Lidar observations of a stratospheric dust cloud layer in the tropics, Geophysical Research Letters, 2, 4, 139-141, Abstract A transparent whitish cloud veil was observed over Hawaii from early October throughout January 2, 1975, the date of submission of this paper. Lidar measurements made from the Mauna Loa Observatory during this period established the height of the layer at about 19.5 km MSL with a typical thickness at half maximum of 800 meters. The nearest Rawinsonde data clearly indicated this height to be above the tropopause. During the month of November, a stratospheric layer was observed by several other workers in the United States which has been attributed to the eruption of Fuego volcano in Guatemala during the month of October. However, the backscatter coefficient observed in the layer over Hawaii was occasionally 20 times greater than that observed at other locations. Although our data support the volcanic hypothesis, there are still some unanswered questions. For example, we observed the layer prior to the major eruption period and the time of appearance of the layer over other observatories in the United States. Furthermore, high altitude aircraft were operating in the stratosphere over Hawaii during the first two weeks of October which may have influenced the cloud formation.
Fromm, M., E.P. Shettle, K.H. Fricke, C. Ritter, T. Trickl, H. Giehl, M. Gerding, J. Barnes, M. O'Neill, S.T. Massie, U. Blum, I.S. McDermid, T. Leblanc and T. Deshler, (2008), Stratospheric impact of the Chisholm pyrocumulonimbus eruption: 2. Vertical profile perspective, Journal of Geophysical Research-Atmospheres, 113, D8, D08203-D08203, doi:10.1029/2007JD009147 Abstract [1] Extreme pyrocumulonimbus (pyroCb) blowups that pollute the stratosphere have been documented on at least five occasions. However, the frequency of these events is still uncertain. One published pyroCb case study, the Chisholm Fire in May 2001, was restricted to the convective phase and its immediate aftermath. Here and in a companion paper we describe the stratospheric impact of the Chisholm pyroCb. The companion paper focuses on nadir satellite views of the plume. This paper synthesizes a broad array of space-, balloon-, and ground-based profile measurements. The Chisholm pyroCb, which we identify as the singular cause of stratospheric aerosol increase in northern spring/summer of 2001, created a doubling of the zonal average aerosol optical depth in the lowermost stratosphere. The meridional spread of the plume was from the tropics (20�N) to the high Arctic (79�N) within the first month. The stratospheric Chisholm smoke became a hemispheric phenomenon in midlatitudes and northern tropics and persisted for at least 3 months. A size-resolved particle concentration profile over Laramie, Wyoming, indicated a lower stratospheric aerosol with a twofold to threefold increase in volume of particles with radii between 0.3 and 0.6 ?m. We also find evidence of localized warming in the air masses of four of the lidar-measured smoke layers. This work contains the first reported stratospheric smoke layers measured by lidar at Ny �lesund, Esrange, K�hlungsborn, Garmisch-Partenkirchen, Boulder, and Mauna Loa. In addition, the first detection of smoke-enhanced aerosol extinction at near IR wavelengths by the Halogen Occultation Experiment (HALOE) is introduced.
Fujiwara, M., B. Johnson, H. Kelder, N. P. Leme, G. Konig-Langlo, E. Kyro, G. Laneve, L. S. Fook, J. Merrill, G. Morris, M. Newchurch, S. Oltmans, M. C. Parrondos, F. Posny, F. Schmidlin, P. Skrivankova, R. Stubi, D. Tarasick, A. Thompson, V. Thouret, P. Viatte, Holger V�mel, P. von Der Gathen, M. Yela and G. Zablocki, (2007), Validation of Aura Microwave Limb Sounder Ozone by Ozonesonde and Lidar Measurements, Journal of Geophysical Research Atmospheres, 112, D24S34, , 10.1029/2007JD008776 Abstract We present validation studies of MLS version 2.2 upper tropospheric and stratospheric ozone profiles using ozonesonde and lidar data as well as climatological data. Ozone measurements from over 60 ozonesonde stations worldwide and three lidar stations are compared with coincident MLS data. The MLS ozone stratospheric data between 150 and 3 hPa agree well with ozonesonde measurements, within 8% for the global average. MLS values at 215 hPa are biased high compared to ozonesondes by ?20% at middle to high latitude, although there is a lot of variability in this altitude region. Comparisons between MLS and ground-based lidar measurements from Mauna Loa, Hawaii, from the Table Mountain Facility, California, and from the Observatoire de Haute-Provence, France, give very good agreement, within ?5%, for the stratospheric values. The comparisons between MLS and the Table Mountain Facility tropospheric ozone lidar show that MLS data are biased high by ?30% at 215 hPa, consistent with that indicated by the ozonesonde data. We obtain better global average agreement between MLS and ozonesonde partial column values down to 215 hPa, although the average MLS values at low to middle latitudes are higher than the ozonesonde values by up to a few percent. MLS v2.2 ozone data agree better than the MLS v1.5 data with ozonesonde and lidar measurements. MLS tropical data show the wave one longitudinal pattern in the upper troposphere, with similarities to the average distribution from ozonesondes. High upper tropospheric ozone values are also observed by MLS in the tropical Pacific from June to November.
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Garc�a, O. E., A. M. D�az, F. J. Exp�sito, J. P. D�az, O. Dubovik, P. Dubuisson, J. C. Roger, T. F. Eck, A. Sinyuk, Y. Derimian, E. G. Dutton, J. S. Schafer, B. N. Holben and C. A. Garc�a, (2008), Validation of AERONET estimates of atmospheric solar fluxes and aerosol radiative forcing by ground-based broadband measurements, Journal of Geophysical Research-Atmospheres, 113, d21, D21207-D21207, doi:10.1029/2008JD010211 Abstract [1] The AErosol RObotic NETwork (AERONET) estimates of instantaneous solar broadband fluxes (F) at surface have been validated through comparison with ground-based measurements of broadband fluxes at Mauna Loa Observatory (MLO) and by the Baseline Surface Radiation (BSRN) and the Solar Radiation Networks (SolRad-Net) during the period 1999�2005 and 1999�2006, respectively. The uncertainties in the calculated aerosol radiative forcing (DF) and radiative forcing efficiency (DFeff) at the bottom of the atmosphere were also assessed. The stations have been selected attempting to cover different aerosols influences and hence radiative properties: urban-industrial, biomass burning, mineral dust, background continental, maritime aerosols and free troposphere. The AERONET solar downward fluxes at surface agree with ground-based measurements in all situations, with a correlation higher than 99% whereas the relation of observed to modeled fluxes ranges from 0.98 to 1.02. Globally an overestimation of 9 � 12 W2 of solar measurements was found, whereas for MLO (clear atmosphere) the differences decrease noticeably up to 2 � 10 W2. The highest dispersion between AERONET estimates and measurements was observed in locations dominated by mineral dust and mixed aerosols types. In these locations, the F and DF uncertainties have shown a modest increase of the differences for high aerosol load, contrary to DFeff which are strongly affected by low aerosol load. Overall the discrepancies clustered within 9 � 12 W2 for DF and 28 � 30 W2 per unit of aerosol optical depth, t, at 0.55 mm for DFeff, where the latter is given for t(0.44 mm) 0.4. The error distributions have not shown any significant tendency with other aerosol radiative properties as well as size and shape particles.
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Hahn, C.J., J.T. Merrill and B. Mendonca, (1992), Meteorolgical influences during MLOPEX, Journal of Geophysical Research-Atmospheres, 97, D10, 10291-10309, 91JD02299 Abstract Meteorological data are presented and discussed for the period May 1 to June 4,1988, in support of the Mauna Loa Observatory Photochemistry Experiment (MLOPEX). Isentropic trajectories were computed to determine air mass origins. Meteorological observations at the Mauna Loa Observatory and radiosonde observations from HiIo, Hawaii, are used to analyze local influences on air mass composition.
Harris, J. M., S. J. Oltmans, E. J. Dlugokencky, P. C. Novelli, B. J. Johnson and T. Mefford, (1998), An investigation into the source of the springtime tropospheric ozone maximum at Mauna Loa Observatory, Geophysical Research Letters, 25, 11, 1895-1898, 98GL01410 Abstract Measurements of CH4, CO, O3, and H2O vapor from Mauna Loa Observatory (MLO) are examined in conjunction with isentropic trajectories to investigate the cause of a maximum in tropospheric O3 consistently observed during spring. CO and O3 have been found to be positively correlated in pollution plumes containing O3 precursors downwind of industrialized regions. However, we report that during continental transport from Asia, O3 is not correlated with either CO or CH4, although CO and CH4 are strongly correlated. The relationship between CO and CH4 suggests common source regions. The lack of correlation between these species and O3 probably indicates an O3 source distinct from that of CO and CH4. While Asian pollution does not appear to be a strong candidate for causing the spring increase in O3, transport characteristics and H2O vapor measurements are consistent with both an upper?tropospheric/stratospheric contribution and an enhancement from transport across O3 gradients.
Harris, J. M., S. J. Oltmans, P. P. Tans, R. D. Evans and D. Quincy, (2001), A new method for describing long-term changes in total ozone, Geophysical Research Letters, 28, 24, 4535-4538, 2001GL013501 Abstract A new method for describing long-term changes in total ozone was developed so that variations on time scales greater than that of the QBO may be examined. The technique fits a flexible tendency curve to total ozone data after explained variations have been removed. The derivative of the tendency curve is the growth rate curve. The average along this curve is comparable to total ozone trends reported in the past. Statistical uncertainty of the growth rate is determined using bootstrap techniques. Dobson column ozone measurements with long-term (30+ years) records from the NOAA/CMDL Cooperative Dobson Network were analyzed. Total ozone decreases ranged from 1-2%/decade since the 1960s and from 2-4%/decade since 1979 at all sites except Mauna Loa where results were not significant. The tendency curves indicate that the total ozone decline began in the 1970s and that there are no clear signs of recovery as of the end of 2000.
Hofmann, D. J., J. Barnes, M. O'Neill, M. Trudeau and R. Neely, (2009), Increase in background stratospheric aerosol observed with LIDAR at Mauna Loa Observatory and Boulder, Colorado, Geophysical Research Letters, 36, L15808, doi:10.1029/2009GL039008 Abstract The stratospheric aerosol layer has been monitored with lidars at Mauna Loa Observatory in Hawaii and Boulder in Colorado since 1975 and 2000, respectively. Following the Pinatubo volcanic eruption in June 1991, the global stratosphere has not been perturbed by a major volcanic eruption providing an unprecedented opportunity to study the background aerosol. Since about 2000, an increase of 4-7 % per year in the aerosol backscatter in the altitude range 20-30 km has been detected at both Mauna Loa and Boulder. This increase is superimposed on a seasonal cycle with a winter maximum that is modulated by the quasibiennial oscillation (QBO) in tropical winds. Of the three major causes for a stratospheric aerosol increase: volcanic emissions to the stratosphere, increased tropical upwelling, and an increase in anthropogenic sulfur gas emissions in the troposphere, it appears that a large increase in coal burning since 2002, mainly in China, is the likely source of sulfur dioxide that ultimately ends up as the sulfate aerosol responsible for the increased backscatter from the stratospheric aerosol layer. The results are consistent with 0.6-0.8% of tropospheric sulfur entering the stratosphere.
Hofmann, D. J., J. H. Butler and P. P. Tans, (2009), A new look at atmospheric carbon dioxide, Atmospheric Environment, 43, 12, 2084-2086, 10.1016/j.atmosenv.2008.12.028 Abstract Carbon dioxide is increasing in the atmosphere and is of considerable concern in global climate change because of its greenhouse gas warming potential. The rate of increase has accelerated since measurements began at Mauna Loa Observatory in 1958 where carbon dioxide increased from less than 1 part per million per year (ppm yr?1) prior to 1970 to more than 2 ppm yr?1 in recent years. Here we show that the anthropogenic component (atmospheric value reduced by the pre-industrial value of 280 ppm) of atmospheric carbon dioxide has been increasing exponentially with a doubling time of about 30 years since the beginning of the industrial revolution (1800). Even during the 1970s, when fossil fuel emissions dropped sharply in response to the �oil crisis� of 1973, the anthropogenic atmospheric carbon dioxide level continued increasing exponentially at Mauna Loa Observatory. Since the growth rate (time derivative) of an exponential has the same characteristic lifetime as the function itself, the carbon dioxide growth rate is also doubling at the same rate. This explains the observation that the linear growth rate of carbon dioxide has more than doubled in the past 40 years. The accelerating growth rate is simply the outcome of exponential growth in carbon dioxide with a nearly constant doubling time of about 30 years (about 2%/yr) and appears to have tracked human population since the pre-industrial era.
Hofmann, D. J., S. J. Oltmans, G.L. Koenig, B.A. Bodhaine, J. M. Harris, J.A. Lathrop, R. C. Schnell, J. Barnes, J. Chin, D. Kuniyuki, S. Ryan, R. Uchida, A. Yoshinaga, P.J. Neale, D.R. J.. Hayes, V.R. Goodrich, W.D. Komhyr, R. D. Evans, B. J. Johnson, D. Quincy and M. Clark, (1996), Record low ozone at Mauna Loa Observatory during winter 1994-1995: A consequence of chemical and dynamical synergism?, Geophysical Research Letters, 23, 12, 1533-1536, GL00150 Abstract During two days in late December 1994, total ozone measured at the Mauna Loa Observatory on the island of Hawaii, dropped below 200 Dobson Units (DU) for the first time since ozone measurements began at this site over 30 years ago. Total ozone values this low have not previously occurred over populated areas except on rare occasions when the edges of the springtime Antarctic ozone hole temporarily pass over the southern tip of Argentina. The monthly total ozone average for January 1995 was 216 DU, about 14% below the 1964-1981 baseline value. Ultraviolet radiation measured at Mauna Loa on clear days during this period increased inversely with ozone as expected, more than tripling in relative intensity at 295 nm. The normal annual minimum in total ozone occurs in winter at Mauna Loa; however, some winters experience considerably lower values than others. This was the case during the winter of 1994-1995. Although the general decline in global ozone, which began about 1980 and also appears in the Mauna Loa record, may be related to chemical ozone depletion, the unusually low values during some winters at Mauna Loa appear to be related to ozone transport from the tropics, and the timing of phase transitions of the QBO. This analysis provides an accurate method of forecasting low-ozone, high-UV winters in Hawaii.
H�bler, Gerhard, D.D. Montzka, Richard B. Norton, P.C. Murphy, F. C. Fehsenfeld, S.C. Liu, B.A. Ridley, J.G. Walega, E. Atlas, F.E. Grahek, L.E. Heidt, J. Merrill, B.J. Huebert and B.A. Bodhaine, (1992), Total reactive oxidized nitrogen (NOy) in the remote Pacific troposphere and its correlation with O3 and CO: Mauna Loa Observatory Photochemistry Experiment 1988, Journal of Geophysical Research-Atmospheres, 97, D10, 10,427-10,447, doi:10.1029/91JD03112 Abstract As part of the Mauna Loa Observatory Photochemistry Experiment (MLOPEX) total reactive oxidized nitrogen (NOy) was measured during May and early June of 1988 at the Mauna Loa Observatory, the NOAA-Geophysical Monitoring for Climatic Change Baseline Monitoring Station, located at 3.4-km elevation on the island of Hawaii. Gold catalytic surface conversion of individual reactive oxidized nitrogen species to NO and subsequent quantification of the NO by NO/O3 chemiluminescence was used to measure the NOy mixing ratio. The NOy abundance at the site was governed by the local downslope/upslope wind systems as well as synoptic-scale transport. With some exceptions, downslope wind brought air representative of the free troposphere, while upslope winds transported air from below the trade wind inversion to the site. The upslope air masses could be a mix of marine boundary layer air and free tropospheric air modified by anthropogenic and natural emissions from island sources. It was possible to identify free tropospheric air in the downslope flow through meteorological and chemical tracers. Reflecting the remote location, low NOy mixing ratios with median values of 262 and 239 pptv were found in free tropospheric and upslope air masses, respectively. The median NOy levels in free tropospheric air are consistent with airborne NOy measurements made during NASA's Global Tropospheric Experiment/Chemical Instrumentation Test and Evaluation (CITE 2) program over the northeastern Pacific Ocean at corresponding altitudes. The median NOy values in upslope flow are significantly higher than those measured in the remote marine boundary layer during CITE 2, reflecting probably the influence of island source and/or mixing of free tropospheric air with boundary layer air. The low correlation found between NOy and tracers of anthropogenic sources, such as carbon monoxide, tetrachloroethylene, and n-propyl nitrate, in free tropospheric air samples is consistent with a stratospheric or upper tropospheric source for NOy. Simultaneous particulate nitrate (NO3 ?) measurements suggest that at times not all aerosol NO3 ? was quantitatively converted to NO by the Au-surf ace converter technique. These episodes were usually found during upslope flow and were characterized by high sodium concentrations, suggesting that possibly the sodium nitrate contained in these aerosols was not converted efficiently by the Au converter.
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Jaffe, D., A. Mahura, J. Kelley, J. Atkins, P. C. Novelli and J. Merrill, (1997), Impact of Asian emissions on the remote North Pacific atmosphere: Interpretation of CO data from Shemya, Guam, Midway and Mauna Loa, Journal of Geophysical Research-Atmospheres, 102, D23, 28627-28635, JD02750 Abstract In this study we look at the concentration of CO at four remote stations in the North Pacific to evaluate the impact of Asian industrial emissions on the remote atmosphere. Using a locally weighted smoothing technique to identify individual data outliers from the seasonal cycle, we have identified 22�92 outliers or �events� (greater than 5 ppbv above the seasonal cycle) at each site for the 3�6 year data records. Using isentropic back trajectories, we identify a possible source region for each event and present a distribution of the trajectory types. For the events at Midway, Mauna Loa, Guam, and Shemya, we are able to identify a source region for the elevated CO in 82, 72, 65, and 50% of the events, respectively. At Mauna Loa and Midway a majority of the events occur during spring and are usually associated with transport from Asia. These events bring the highest CO mixing ratios observed at any time during the year to these sites, with CO enhancements up to 46 ppb. At Guam, easterly trade winds are the norm, but occasionally synoptic events bring Asian emissions to the island, generally during late summer and fall, from either East Asia or Southeast Asia (e.g., Indonesia). These events bring with them the largest CO enhancements of any of the four sites considered in this paper, up to 58 ppb. Finally, to examine the robustness of our conclusions, we redo our analysis using the more stringent definition that an event must be either 10 or 15 ppb above the seasonal cycle. Although this reduces the number of events identified at each site, it does not significantly change the fraction of events which can be attributed to a known source.
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Kato, S., T. P. Ackerman, E. G. Dutton, N. Laulainen and N. Larson, (1999), A comparison of modeled and measured surface shortwave irradiance for a molecular atmosphere, Journal of Quantitative Spectroscopy & Radiative Transfer, 61, 4, 493-502, doi:10.1016/S0022-4073(98)00032-6 Abstract We compare the downward diffuse and direct normal irradiance computed by a two-stream model with measurements taken at the Mauna Loa Observatory when the atmosphere was close to a molecular atmosphere. The modeled downward diffuse irradiance agrees with measurements taken by a shaded pyranometer within the uncertainty of the measurement. Therefore, the two-stream approximation is adequate for computing the downward diffuse irradiance in a molecular atmosphere. This result also indicates that neglecting the state of polarization introduces a negligible error in the irradiance computation.
Kaufman, Y.G., S.S. Khmelevtsov and T.E. DeFoor, (1993), Lidar measurements of stratospheric aerosols during the SAGA 3 expedition, Journal of Geophysical Research-Atmospheres, 98, D9, 16909-16913, 10.1029/93JD00326 Abstract Backscatter lidar measurements of stratospheric aerosols were carried out over the tropical Pacific aboard the Akademik Korolev during SAGA 3 of February to March 1990. Measurements were made using a Maket 1 lidar system from the Institute of Experimental Meteorology. Regions of enhanced stratospheric backscatter, apparently from the February 10, 1991, eruption of Kelut (7.9�S, 112.3�E), were detected on several occasions. Integrated non-Rayleigh backscatter at 532 nm between 16 km and 33 km ranged from a background value of 1.5 � 10?4 sr?1 to as high as 14.5 � 10?4 sr?1 in the volcanic plume. During the Akademik Korolev port of call at HiIo, Hawaii, at the start of SAGA 3, intercomparisons were attempted with the NOAA, ERL, CMDL Mauna Loa Observatory lidar located approximately 60 km SW at Mauna Loa Observatory (19.5�N, 155.6�W). The intercomparison results were encouraging but were inconclusive because of limited data and signal degradation resulting from poor observing conditions due to bad weather.
Kim, H.S., Y. S. Chung and P. P. Tans, (2010), On the regional distributions of background carbon monoxide concentrations observed in East Asia during 1991-2008, Asia-Pacific Journal of Atmospheric Sciences, , , 10.1007/s13143-010-0009-0 Abstract The carbon monoxide (CO) concentrations observed at Mt. Waliguan in China (WLG), Ulaan Uul in Mongolia (UUM), Tae-ahn Peninsula in Korea (TAP) and Ryori in Japan (RYO) were analysed between 1991 and 2008. The average annual concentration of CO, a toxic air pollutant, was the highest at TAP (235±44 ppb), followed by RYO (169±35 ppb), UUM (154±27 ppb) and WLG (138±24 ppb). These data obtained in East Asia were also compared with CO data from Mauna Loa, Hawaii. CO tends to be highest in spring and lowest in summer in East Asia, with the exception of WLG. TAP had the highest CO concentrations in all seasons compared with WLG, UUM and RYO, and displays a wide short-term variability in concentration. This is caused by large-scale air pollution owing to its downwind location, close to continental East Asia. CO concentrations observed at TAP were analysed as follows: according to the origin of the isentropic backward trajectory and its transport passage; as continental background airflows (CBG); regionally polluted continental airflows (RPC); oceanic background airflows (OBG); and partly perturbed oceanic airflows (PPO). The high concentrations of CO at TAP are because of the airflow originating from the East Asian continent, rather than the North Pacific. RPCs, which pass through eastern China, appear to have high CO concentrations in spring, autumn and winter. It is noteworthy that the overall trend at TAP does not show an increase despite the fact that energy use in China approximately doubled from 1991 to 2008. OBGs, however, are affected by North Pacific air masses with low CO concentrations in summer.
Kim, J., S.-N. Oh, H.-M. Cho, P. Mi-Kyung, K.-R. Kim and J. W. Elkins, (2001), Background Monitoring and Long-range Transport of Atmospheric CFC-11 and CFC-12 at Kosan, Korea, Environmental Monitoring and Assessment, 70, 1-2, 47-56, 10.1023/A:1010640004389 Abstract The background concentrations of atmospheric CFC-11 and CFC-12were monitored to assess their impact on stratospheric ozone depletion and global warming from September 1995 to March 1999 at Kosan, Korea, located at eastern margin of the Asian Continent. The concentrations of atmospheric CFC-11 at Kosan have decreased slightly, at a rate of �2.5 pptv yr-1, over the period in response to the Montreal Protocol. The CFC-12 mixing ratio at Kosan continues to increase in the atmosphere at a rate of 5.7 pptv yr-1 despite international regulations, because of its extreme atmosphere persistence. Recent trends ofthese two chlorofluorocarbons at Kosan, Korea were concordant with those of the northern hemispheric background monitored unitat Mauna Loa, Hawaii. The maximum seasonal mean mixing ratios of CFC-11 and CFC-12 at Kosan, Korea, were 270�4 pptv inthe spring and 538�9 pptv in the winter, and the corresponding seasonal minima were 267�7 and 529�12 pptv. This occurred in the summer and was due to southeasterlywinds from the northwestern Pacific Ocean. By performing a three-day isentropic backward trajectory analysis, it was shownthat air masses at Kosan, and with the exception of summer, mainly originated from central and northern China. In particular, the mixing ratios of these two contaminant speciesare closely related with their air mass trajectories.
Kim, S. -W., S. -C. Yoon, E. G. Dutton, C. Wehrli and B. Holben, (2008), Global Surface-based Sun Photometer Network for Long-term Observations of Column Aerosol Optical Properties: Intercomparison of Aerosol Optical Depth, Aerosol Science and Technology, 42, 1-9, DOI: 10.1080/02786820701699743 Abstract Comparisons of aerosol optical depths (AODs) determined from several types of Sun photometers operating side by side as part of four different networks (GAW PFR, AERONET, SKYNET, and NOAA/ESRL aerosol monitoring programs) were made at 6 different environmental stations to evaluate the different types of current state-of-the-art instruments under different aerosol loading conditions. A comparison between AERONET CIMEL and GAW PFR at a high altitude calibration site, Mauna Loa, shows an excellent agreement with 0.001 bias for 500 nm AOD. AODs obtained from direct Sun-pointing instruments are within 0.01 bias, though these results are similar to or slightly larger than those given in previous short-term intensive studies. These results suggest that well-maintained networks of direct Sun-pointing instruments developed by different companies/institutions can provide quality-assured AOD data across the globe to the aerosol-climate research community. The poorer agreement between a hemispherical field-of-view (FOV) MFRSR and the finite FOV Sun-pointing instrument is found to be due to uncertainty in the angular characterization of the MFRSR optics.
Komhyr, W. D., (1983), An aerosol and gas sampling apparatus for remote observatory use, Journal of Geophysical Research, 88, C6, 3913-3918, 10.1029/JC088iC06p03913 Abstract An air sampling apparatus is described which standardizes sampling height at a field station at 10 m or more above ground level and which minimizes loss of particles and destruction and contamination of sampled trace atmospheric gases as air is conducted through the apparatus to various monitoring instruments. Basic design features render the apparatus useful for air sampling under widely varying climate conditions, and at station altitudes ranging from sea level to more than 4 km. Four systems have been built, and have been used sucessfully since 1977 at the NOAA Geophysical Monitoring for Climatic Change program baseline stations at Point Barrow, Alaska; Mauna Loa, Hawaii; American Samoa, South Pacific; and South Pole, Antarctica.
Komhyr, W. D., G. C. Reinsel, R. D. Evans, D. Quincy, R. D. Grass and R. K. Leonard, (1997), Total ozone trends at sixteen NOAA/CMDL and Cooperative Dobson Spectrophotometer Observatories during 1979-1996, Geophysical Research Letters, 24, 24, 3225-3228, 97GL03313 Abstract Ozone trends, derived from 1979-1996 Dobson spectrophotometer total ozone data obtained at five U.S. mainland midlatitude stations, averaged -3.4, -4.9, -2.6, -1.9, and -3.3%/decade for winter, spring, summer, and autumn months, and on an annual basis, respectively. At the lower latitude stations of Mauna Loa and Samoa, corresponding-period annual ozone trends were -0.4 and -1.3%/decade, respectively, while at Huancayo, Peru, the 1979-1991 annual trend was -0.9%/decade. A linear trend approximation to ozone changes that occurred since 1978 during austral daylight times at Amundsen-Scott (South Pole) station, Antarctica, yielded a value of -12%/decade. By combining 1979-1996 annual trend data for three U.S. mainland stations with trends for the sites derived from 1963-1978 data, it is estimated that the ozone decrease at U.S. midlatitudes through 1996, relative to ozone present in the mid-1960s, was -6.7%. Similar analyses incorporating South Pole data obtained since 1963 yielded an ozone change at South Pole (daylight observations) through 1996 of approximately -25%. South Pole October total ozone values in 1996 were lower than mid-1960s October ozone values by a factor of two. Trend data are also presented for several shorter record period stations, including the foreign cooperative stations of Haute Provence, France; Lauder, New Zealand; and Perth, Australia.
Komhyr, W.D., R.D. Grass and R.K. Leonard, (1989), Dobson Spectrophotometer 83: A Standard for Total Ozone Measurements, 1962-1987, Journal of Geophysical Research-Atmospheres, 94, d7, 9847-9861, doi:10.1029/JD094iD07p09847 Abstract Dobson spectrophotometer 83 was established in 1962 as a standard for total ozone measurements in the United States. In 1980 the instrument was designated by the World Meteorological Organization (WMO) as the primary standard Dobson spectrophotometer for the world. Since the early 1960s, virtually all (?90) Dobson instruments in the global Dobson instrument network have been calibrated several times, either directly or indirectly, relative to instrument 83. Calibrations of instrument 83 by the Langley method were performed in 1962 at Sterling, Virginia, and during 1972�1987 at Mauna Loa Observatory (MLO), Hawaii. A detailed analysis of these calibration data, as well as calibration data based on standard lamp measurements made since 1962, indicates that the long-term (25-year) ozone measurement precision for the instrument is known to within a uncertainty of �0.5%. On an absolute scale, the ozone measurements made at MLO with instrument 83 are estimated to be too low by about 2.4%, as a result of errors in the A and D wavelength ozone absorption coefficients used with the instrument and their temperature dependence. Cumulative other biases most likely do not exceed �1%. This documentation of the calibration history of instrument 83 lends credence to the accuracy with which other Dobson instruments have been calibrated in the past and to Dobson and satellite instrument ozone measurement comparisons, thereby increasing confidence in ozone trends determined by these ozone measurement systems in recent years.
Komhyr, W.D., T.B. Harris, L.S. Waterman, J.F.S. Chin and K. W. Thoning, (1989), Atmospheric Carbon Dioxide at Mauna Loa Observatory 1. NOAA Global Monitoring for Climatic Change Measurements With a Nondispersive Infrared Analyzer, 1974-1985, Journal of Geophysical Research-Atmospheres, 94, D6, 8533-8547, JD094iD06p0853 Abstract Atmospheric CO2 measurements made with a nondispersive infrared analyzer during 1974-1985 at Mauna Loa Observatory, Hawaii, are described, with emphasis on the measurement methodology, calibrations, and data accuracy. Monthly mean CO2 data, representative of global background conditions, are presented for the period of record. The monthly means were derived from an all-data base of CO2 hourly averages archived at the National Oceanic and Atmospheric Administration (NOAA) Geophysical Monitoring for Climatic Change (GMCC) facility in Boulder, Colorado; at the Carbon Dioxide Information Analysis Center (CDIAC) in Oak Ridge, Tennessee; and in the microfiche version of this paper. Flags in the all-data base identify CO2 hourly averages that have been deemed unreliable because of sampling and analysis problems or that are unrepresentative of clean background air because of influences of the local environment, for example, CO2 uptake by nearby vegetation or contamination and pollution effects. The select NOAA GMCC monthly mean data are compared with similar data obtained independently at Mauna Loa Observatory by the Scripps Institution of Oceanography. The average difference of corresponding monthly mean CO2 values for the two data sets is 0.15 ± 0.18 ppm, where the indicated variability is the standard deviation. Careful scrutiny of the NOAA GMCC measurement, calibration, and data processing procedures that might have caused the small bias in the data has revealed no unusual errors.
Kulawik, S, D. B Jones, R Nassar, F Irion, J.R Worden, K Bowman, T Machida, H Matsueda, Y Sawa, S. C Biraud, M. L Fischer and A. R. Jacobson, (2010), Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science, Atmospheric Chemistry and Physics, 10, 5601-5623, 10.5194/acp-10-5601-2010 Abstract We present carbon dioxide (CO2) estimates from the Tropospheric Emission Spectrometer (TES) on the EOS-Aura satellite launched in 2004. For observations between 40� S and 45� N, we find about 1 degree of freedom with peak sensitivity at 511 hPa. The estimated error is ~10 ppm for a single target and 1.3�2.3 ppm for monthly averages on spatial scales of 20��30�. Monthly spatially-averaged TES data from 2005�2008 processed with a uniform initial guess and prior are compared to CONTRAIL aircraft data over the Pacific ocean, aircraft data at the Southern Great Plains (SGP) ARM site in the southern US, and the Mauna Loa and Samoa surface stations. Comparisons to Mauna Loa data show a correlation of 0.92, a standard deviation of 1.3 ppm, a predicted error of 1.2 ppm, and a ~2% low bias, which is subsequently corrected. Comparisons to SGP aircraft data over land show a correlation of 0.67 and a standard deviation of 2.3 ppm. TES data between 40� S and 45� N for 2006�2007 are compared to surface flask data, GLOBALVIEW, the Atmospheric Infrared Sounder (AIRS), and CarbonTracker. Comparison to GLOBALVIEW-CO2 ocean surface sites shows a correlation of 0.60 which drops when TES is offset in latitude, longitude, or time. At these same locations, TES shows a 0.62 and 0.67 correlation to CarbonTracker at the surface and 5 km, respectively. We also conducted an observing system simulation experiment to assess the potential utility of the TES data for inverse modeling of CO2 fluxes. We find that if biases in the data and model are well characterized, the averaged data have the potential to provide sufficient information to significantly reduce uncertainty on annual estimates of regional CO2 sources and sinks. Averaged pseudo-data at 10��10� reduced uncertainty in flux estimates by as much as 70% for some tropical regions.
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Lantz, K. O., R. E. Shetter, C. A. Cantrell, S. J. Flocke, J. G. Calvert and S. Madronich, (1996), Theoretical, actinometric, and radiometric determinations of the photolysis rate coefficient of NO2 during the Mauna Loa Observatory Photochemistry Experiment II, Journal of Geophysical Research Atmospheres, 101, D9, 14613-14630, Abstract Measurements of the photolysis rate coefficient of NO2 (jNO2) were made using a chemical actinometer during the fall (September 15 to October 23, 1991), winter (January 15 to February 15, 1992), spring (April 15 to May 15, 1992), and summer (July 15 to August 15, 1992) intensives during the second Mauna Loa Observatory Photochemistry Experiment (MLOPEX 2), Hawaii. The measured clear sky jNO2 values of MLOPEX 2 for all four intensives have substantially increased over the measured jNO2 values of MLOPEX 1 (May, 1988); a 37% increase occurs in midday clear sky jNO2 from the spring intensive of MLOPEX 1 to the spring intensive of MLOPEX 2. The ratio of actinometer measurements to theoretical calculations of jNO2 are 1.44�0.03, 1.45�0.02, 1.43�0.03, and 1.34�0.02 for the fall, winter, spring, and summer intensives, respectively. Inclusion of stratospheric aerosols or aerosols of any reasonable optical parameters in a detailed discrete ordinate model cannot account for the discrepancy between measurements and model. The photolysis rate coefficient of NO2 is also derived from simultaneous measurements of the ultraviolet irradiance measured with an Eppley radiometer using a semiempirical relationship for each of the four intensives. A simplified cloud model is proposed to explain jNO2 values that exceed clear sky values during days that have partial cloud coverage.
Levinson, D. H. and A. M. Waple, (2005), State of the Climate in 2004, Bulletin of the American Meteorological Society, 86, S1-S86, 10.1175/BAMS-86-6-Levinson Abstract From a global perspective, the annual average surface temperature in 2004 was the fourth highest value observed since regular instrumental records began in 1880. Global surface air temperatures in 2004 were 0.44�C (0.79�F) above the 1961�90 mean, according to both the U.S. and U.K. archives. Observations of the global annual mean temperature in 2004 from the combined lower and middle troposphere was 0.38�C (0.68�F)�the fourth warmest year in the 47-yr archive of worldwide radiosonde observations, and the ninth warmest year out of the past 26 based on satellite measurements. The average precipitation anomaly over global land areas in 2004 was 10.7 mm above average, which was 1% above the 1961�90 mean, and the first year since 2000 that the global mean value was wetter than average. Northern Hemisphere sea ice extent was the third lowest on record for the year, dating back to 1973. The annual snow cover extent over Northern Hemisphere land areas was 25.1 million km2, which was the 25th most extensive snow cover during the period of record. Levels of carbon dioxide (CO2) continue to increase in the atmosphere at the NOAA/Climate Modeling and Diagnostics Laboratory (CMDL) Mauna Loa Observatory on the Big Island of Hawaii; CO2 rose approximately 1.3 parts per million (ppm) in 2004, to reach a preliminary value of 377.6 ppm. However, the 2004 increase was below the long-term average increase of 1.5 ppm yr?1. A minimum ozone concentration of 138 Dobson units (DU) was measured on 4 October 2004 at South Pole station, which was above the 1986�2004 average minimum value of 117 �26 DU. Sea levels continued to rise globally, increasing at a rate of 2.8 �0.4 mm yr?1 based on satellite altimeter measurements. The satellite measurements since 1993 have recorded a significantly higher rise in sea level than the overall twentieth-century rate of 1.8 �0.3 mm yr?1, determined from tide gauge observations during the past century. The climate of 2004 was influenced by the development of a weak El Ni�o (i.e., ENSO warm event) in the western and central equatorial Pacific Ocean during the second half of the year. A series of westerly wind bursts during July�October, which were initiated by Madden�Julian oscillation activity in the tropical western Pacific, generated several Kelvin waves in the oceanic mixed layer that aided in the formation of the warm event. Only limited regional-scale impacts associated with El Ni�o occurred during the boreal autumn, because the event did not develop basinwide. Tropical cyclone activity was above average in the North Atlantic, west North Pacific, and South Indian Ocean basins in 2004. The hurricane season was extremely active in the North Atlantic basin, with a total of 15 named storms, nine hurricanes, and six major hurricanes in 2004. Nine of these tropical cyclones struck the Atlantic and Gulf of Mexico coasts of the United States, with three of these landfalling as major hurricanes. The first documented hurricane developed in the South Atlantic Ocean (cyclone �Catarina�), which made landfall along the southern coast of Brazil in late March. The west North Pacific typhoon season was also very active, with 10 tropical systems making landfall in Japan, breaking the previous record of 6 during a single season. In the South Indian Ocean, Tropical Cyclone Gafilo devastated Madagascar, making landfall as a category 5 supercyclone. From a regional perspective, the annual mean temperature across Europe as a whole in 2004 was 0.98�C above the 1961�90 base period average, with temperature anomalies in excess of 1�C measured across parts of northwest Europe and Scandinavia. Temperatures were also warm across South America and parts of Asia. The annual average temperature in Russia was 0.8�C above the long term mean, but temperatures in 2004 were anomalously cold in Asian Russia. Drought conditions continued across western North America, although conditions improved in the southwest United States and California late in the year, while the multiyear drought persisted in parts of the Pacific Northwest and Northern Rockies. Drought conditions also persisted across a majority of the Greater Horn and southern Africa. Monsoonal rains were deficient across the Indian subcontinent in 2004; only 87% of the long period average rainfall was recorded. In contrast, above-normal rainfall across parts of Southwest Asia helped ease some of the long-running drought conditions in the region.
Luria, M., J.F. Boatman, J. M. Harris, J. Ray, T. Straube, J. Chin, R.L. Gunter, G. Herbert, T.M. Gerlach and C.C. Van Valin, (1992), Atmospheric sulfur dioxide at Mauna Loa, Hawaii, Journal of Geophysical Research-Atmospheres, 97, D5, 6011-6022, 91JD03126 Abstract Measurements of sulfur dioxide (S02) were made at the National Oceanic and Atmospheric Administration's Mauna Loa Observatory in Hawaii, during a 12-month period beginning in December 1988. SO2 concentrations varied from background levels of less than 0.05 ppbv to a maximum of 50 ppbv, during episodes that lasted from 2 to 24 hours. Emissions from the Kilauea crater, approximately 35 km southeast of the observatory at an elevation of about 1000 m above sea level (asl), and the current eruption at Puu O?o 50 km east-southeast, are the most likely sources for the higher concentrations. These episodes occurred 10�25 times each month, mostly during the day; peak concentrations were usually recorded at mid-day. The SO2 concentrations can be grouped into three periods; low (June-September), high (October-January) and intermediate (February-May). A clear diurnal cycle of SO2 concentration exists throughout the year, although day-night changes were greatest during October-January and were barely detectable during the June-September period. The highest SO2 concentrations were recorded when the predominant wind direction was northerly to northwesterly, even though the apparent sources are in the southeastern sector. Nighttime concentrations were usually at background levels; however, many exceptions were observed. A few cases of higher than background SO2 were observed when free tropospheric (FT) conditions were identified. The possibility that long-range transport was the cause for elevated SO2 concentrations under FT conditions was examined using air mass back trajectories analyses. The highest nighttime SO2 concentrations, under FT conditions, were observed during periods with slow easterly trajectories, and the lowest concentrations were found during westerly flows. Twenty-four nighttime free tropospheric events were recorded when the SO2 concentration exceeded 0.2 ppbv. During 18 of these episodes, unusually high CO2 concentrations were observed.
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Machta, L., (1972), Mauna Loa and global trends in air quality, Bulletin of the American Meteorological Society, 53, 5, 402-420, doi:10.1175/1520-0477(1972)053<0402:MLAGTI>2.0.CO;2 Abstract The geophysical observatory at Mauna Loa was established as part of the U.S. contribution to the International Geophysical Year in 1957 largely at the instigation of the late Dr. Harry Wexler. Its record of carbon dioxide concentration in clean air is unique. There is much concern in recent years lest the growing pace of man's activities affect the weather or climate on a large scale. Among the prime constituents of the air which may cause such changes are carbon dioxide and dust. Both of these elements are monitored at Mauna Loa. The upward trend of carbon dioxide superimposed on a seasonal variation confirm the contribution from man's combustion of fossil fuels but the normal incidence solar radiation measurements exhibit no long term trend other than that due to volcanic activity beginning with the eruption at Mt. Agung in 1963. The records of atmospheric carbon dioxide and normal incidence solar radiation of several other stations confirm the carbon dioxide trends but temperate latitude stations show no decrease in normal incidence solar radiation. The ultimate objective of monitoring is the prediction of future concentrations so that their impact on the environment can alert society for a need to control its activity if necessary. The future prediction of atmospheric carbon dioxide based on a simple atmosphere-ocean-biosphere model calibrated by bomb carbon-14 leads to prediction of about 380 ppm in the year 2000 with many reservations.
McPeters, R.D., D. J. Hofmann, M. Clark, L. Flynn, L. Froidevaux, M. Gross, B. Johnson, G. Koenig, X. Liu, S. McDermid, T. McGee, F. Murcray, M.J. Newchurch, S. J. Oltmans, A. Parrish, R. C. Schnell, U. Singh, J.J. Tsou, T. Walsh and J.M. Zawodny, (1999), Results from the 1995 Stratospheric Ozone Profile Intercomparison at Mauna Loa, Journal of Geophysical Research-Atmospheres, 104, D23, 30505-30514, JD900760 Abstract In August 1995, multiple instruments that measure the stratospheric ozone vertical distribution were intercompared at the Mauna Loa Observatory, Hawaii, under the auspices of the Network for the Detection of Stratospheric Change. The instruments included two UV lidar systems, one from the Jet Propulsion Laboratory and the other from Goddard Space Flight Center, electrochemical concentration cell balloon sondes, a ground-based microwave instrument, Dobson-based Umkehr measurements, and a new ground-based Fourier transform infrared instrument. The Microwave Limb Sounder instrument on the Upper Atmosphere Research Satellite provided correlative profiles of ozone, and there was one close overpass of the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument. The results show that much better consistency among instruments is being achieved than even a few years ago, usually to within the instrument uncertainties. The different measurement techniques in this comparison agree to within �10% at almost all altitudes, and in the 20�45 km region most agreed within �5%. The results show that the current generation of lidars is capable of accurate measurement of the ozone profile to a maximum altitude of 50 km. SAGE II agreed well with both lidar and balloon sonde down to at least 17 km. The ground-based microwave measurement agreed with other measurements from 22 km to above 50 km. One minor source of disagreement continues to be the pressure-altitude conversion needed to compare a measurement of ozone density versus altitude with a measurement of ozone mixing ratio versus pressure.
McPeters, R. D. and W. D. Komhyr, (1991), Long-term changes in the total ozone mapping spectrometer relative to world primary standard Dobson spectrometer 83, Journal of Geophysical Research Atmospheres, 96, D2, 2987-2993, 10.1029/90JD02091 Abstract We have examined the stability of the calibration of the Nimbus 7 solar backscatter ultraviolet (SBUV) and total ozone mapping spectrometer (TOMS) instruments by comparing their ozone measurements with those made by a single, very stable Dobson instrument: the world primary standard Dobson spectrometer number 83. Measurements of ozone made with instrument 83 at Mauna Loa observatory in eight summers between 1979 and 1989 were compared with coincident TOMS ozone measurements. The comparison shows that relative to instrument 83, ozone measured by TOMS (and SBUV) was stable between 1979 and approximately 1983, had decreased by 3% by 1986, and had decreased by almost 7% by 1989. A similar time dependence is seen when data from an ensemble of 39 Dobson stations throughout the world is compared with TOMS over the period 1979�1987. The most likely reason for the relative drift is that the diffuser plate used by both SBUV and TOMS to measure solar flux has suffered an uncorrected wavelength dependent degradation, with most of the degradation occurring after 1983. The recently released version 6 TOMS data, corrected using the internal �pair justification� technique, show almost no drift relative to Dobson instrument 83. We conclude from these comparisons that accurate measurements of long-term global ozone change will require a coherent system incorporating both ground based and satellite based ozone measurements.
Mendonca, B. and G. Langer, (1973), Ice Nucleus Counts in Varying Ambient Humidities Using an NCAR Ice Nucleus Counter, Journal of the Atmospheric Sciences, 30, 7, 1452-1454, doi:10.1175/1520-0469(1973)030<1452:INCIVA>2.0.CO;2 Abstract It is of interest to check the validity of the ice nucleus concentrations obtained by the operation of the NCAR ice nucleus counters (Langer, 1973) at the Mauna Loa Observatory under different ambient air humidities to ascertain if the ice nucleus activation in the NCAR counter will vary at a given temperature with relative humidity of the air sampled, all else being equal. This could be due to humidity conditions varying in the NCAR counter with the ambient humidity of the air sampled, with the net result that counts at a given temperature will fluctuate with the initial relative humidity of the air sampled. There are two aspects of this problem: first, the influence of the ambient relative humidity on the subsequent activity of an ice nucleus as the air is cooled to activation temperature; and second probably the critical aspect- the extent to which the relative humidity or supersaturation of the sampled air at the activation temperature influences ice activity.
Mendonca, B. and R.F. Pueschel, (1973), Ice Nuclei, Total Aerosol, and Climatology at Mauna Loa, Hawaii, Journal of Applied Meteorology, 12, 1, 156-160, doi:10.1175/1520-0450(1973)012<0156:INTAAC>2.0.CO;2 Abstract The simultaneous operation of two NCAR ice nuclei counters and an integrating nephelometer at Mauna Loa Observatory over a period of 9 months shows concentration changes in the ice nuclei population that vary in direct relation to the atmospheric light scattering coefficient. Furthermore, both of these atmospheric parameters are strongly correlated with local climatology. 1) lowest values of ice nuclei concentrations and Rayleigh scattering exist when subsiding air or a strong temperature inversion prevents the advection of sub-inversion air to the monitoring site; 2) an increased frequency of higher ice nuclei counts and Increased light scattering over a period of several hours are found when mesoscale atmospheric mixing occurs; and 3) the highest number of ice nuclei and maximum light scatter are encountered when a thermally induced air flow advects sub-inversion air to the Observatory site. These findings suggest the absence of extraterrestrial sources for light scattering and ice nucleating material, and point toward the existence of sources for both on Hawaii.
Mendonca, B. G., K. J. Hanson and J. Deluisi, (1978), Volcanically related secular trends in atmospheric transmission at Mauna Loa Observatory, Science, 202, 4367, 513-515, 10.1126/science.202.4367.513 Abstract Twenty years of atmospheric transmission data from Mauna Loa Observatory show secular decreases at irregular intervals. In addition, a regular annual variation is present during unperturbed as well as perturbed periods. These variations in transmission can be measured to a few tenths of a percent from the data record. Transient decreases in transmission are strongly correlated with explosive volcanic eruptions that inject effluent into the stratosphere. Recovery from these ejections takes as much as 8 years and the recovery curve is linear. Observations in 1977 at Mauna Loa show that, for the first time since the Mount Agung eruption in 1963, the atmospheric transmission of direct-incidence solar irradiation at Mauna Loa returned to values measured in 1958 to 1962.
Michalsky, J. J., F. Denn, C. Flynn, G. B. Hodges, P. Kiedron, A. Koontz, J. Schlemmer and S. E. Schwartz, (2010), Climatology of aerosol optical depth in north-central Oklahoma: 1992-2008, Journal of Geophysical Research-Atmospheres, 115, D07203, 1-16, doi:10.1029/2009JD012197 Abstract Aerosol optical depth (AOD) has been measured at the Atmospheric Radiation Measurement Program central facility near Lamont, Oklahoma, since the fall of 1992. Most of the data presented are from the multifilter rotating shadowband radiometer, a narrow-band, interference-filter Sun radiometer with five aerosol bands in the visible and near infrared; however, AOD measurements have been made simultaneously and routinely at the site by as many as three different types of instruments, including two pointing Sun radiometers. Scatterplots indicate high correlations and small biases consistent with earlier comparisons. The early part of this 16 year record had a disturbed stratosphere with residual Mt. Pinatubo aerosols, followed by the cleanest stratosphere in decades. As such, the last 13 years of the record reflect changes that have occurred predominantly in the troposphere. The field calibration technique is briefly described and compared to Langley calibrations from Mauna Loa Observatory. A modified cloud-screening technique is introduced that increases the number of daily averaged AODs retrieved annually to about 250 days compared with 175 days when a more conservative method was employed in earlier studies. AODs are calculated when the air mass is less than six; that is, when the Sun's elevation is greater than 9.25°. The more inclusive cloud screen and the use of most of the daylight hours yield a data set that can be used to more faithfully represent the true aerosol climate for this site. The diurnal aerosol cycle is examined month-by-month to assess the effects of an aerosol climatology on the basis of infrequent sampling such as that from satellites.
Miller, J. B., K.A. Mack, R. Dissly, J.W.C. White, E. J. Dlugokencky and P. P. Tans, (2002), Development of analytical methods and measurements of 13C/12C in atmospheric CH4 from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network, Journal of Geophysical Research-Atmospheres, 107, d13, 4178, doi:10.1029/2001JD000630 Abstract We describe the development of an automated gas chromatography-isotope ratio mass spectrometry (GC-IRMS) system capable of measuring the carbon isotopic composition of atmospheric methane (?13CH4) with a precision of better than 0.1�. The system requires 200 mL of air and completes a single analysis in 15 min. The combination of small sample size, fast analysis time, and high precision has allowed us to measure background variations in atmospheric ?13CH4 through the NOAA Climate Monitoring and Diagnostics Laboratory Cooperative Air Sampling Network. We then present a record of ?13CH4 obtained from six surface sites of the network between January 1998 and December 1999. The sites are Barrow, Alaska (71�N); Niwot Ridge, Colorado (40�N); Mauna Loa, Hawaii (20�N); American Samoa (14�S); Cape Grim, Tasmania (41�S); and the South Pole (90�S). For the years 1998 and 1999, the globally averaged surface ?13C value was ?47.1�, and the average difference between Barrow and the South Pole was 0.6�. Consistent seasonal variations were seen only in the Northern Hemisphere, especially at Barrow, where the average amplitude was 0.5�. Seasonal variations in 1998, however, were evident at all sites, the cause of which is unknown. We also use a two-box model to examine the extent to which annual average ?13C and CH4 mole fraction measurements can constrain broad categories of source emissions. We find that the biggest sources of error are not the atmospheric ?13C measurements but instead the radiocarbon-derived fossil fuel emission estimates, rate coefficients for methane destruction, and isotopic ratios of source emissions.
Miller, J. M. and J. F. S. Chin, (1978), Short-term disturbances in the carbon dioxide record at Mauna Loa Observatory, Geophysical Research Letters, 5, 8, 669-671, 10.1029/GL005i008p00669 Abstract Short?term disturbances in the carbon dioxide record at Mauna Loa Observatory have been observed since measurements were begun in 1958. These variations are easily recognized and documented on the CO2 record and must be deleted if only the baseline data are to be analyzed. By use of a simple wind analysis technique it was shown that the probable source of these CO2 disturbances since 1976 is venting in the crater of the Mauna Loa volcano during southerly flow.
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Neely, Ryan R., Jason M. English, Owen B. Toon, Susan Solomon, Michael Mills and Jeffery P. Thayer, (2011), Implications of extinction due to meteoritic smoke in the upper stratosphere, Geophysical Research Letters, 38, 24, , 10.1029/2011GL049865 Abstract Recent optical observations of aerosols in the upper stratosphere and mesosphere show significant amounts of extinction at altitudes above about 40 km where the stratospheric sulfate aerosol layer ends. Recent modeling of this region reveals that meteoritic smoke settling from the mesosphere and its interaction with the upper part of the sulfate aerosol layer is the origin of the observed extinction. Extinction in this region has major implications for the interpretation and analysis of several kinds of aerosol data (satellite and lidar). We compare observations from the SAGE II satellite and from NOAA's lidar located at Mauna Loa, Hawaii to extinction profiles derived from the Whole Atmosphere Community Climate Model (WACCM) coupled with the Community Aerosol and Radiation Model for Atmospheres (CARMA). Our results show that a major source of extinction exists in the region above about 30 km that must be addressed by all remote sensing instruments that have traditionally used the stratosphere above about 30 km as an aerosol free region to estimate the molecular component of their total extinction. It is also shown that meteoritic smoke not only contributes to but also becomes the dominant source of aerosol extinction above 35 km and poleward of 30 degrees in latitude, as well as above 40 km in the tropics. After addressing the concerns described here, current and past observations of this region could be reanalyzed to further our understanding of meteoritic dust in the upper stratosphere.
Noone, David, Joseph Galewsky, Zachary D. Sharp, John Worden, John Barnes, Doug Baer, Adriana Bailey, Derek P. Brown, Lance Christensen, Eric Crosson, Feng Dong, John V. Hurley, Leah R. Johnson, Mel Strong, Darin Toohey, Aaron Van Pelt and Jonathon S. Wright, (2011), Properties of air mass mixing and humidity in the subtropics from measurements of the D/H isotope ratio of water vapor at the Mauna Loa Observatory, Journal of Geophysical Research, 116, D22, , 10.1029/2011JD015773 Abstract Water vapor in the subtropical troposphere plays an important role in the radiative balance, the distribution of precipitation, and the chemistry of the Earth's atmosphere. Measurements of the water vapor mixing ratio paired with stable isotope ratios provide unique information on transport processes and moisture sources that is not available with mixing ratio data alone. Measurements of the D/H isotope ratio of water vapor from Mauna Loa Observatory over 4 weeks in October–November 2008 were used to identify components of the regional hydrological cycle. A mixing model exploits the isotope information to identify water fluxes from time series data. Mixing is associated with exchange between marine boundary layer air and tropospheric air on diurnal time scales and between different tropospheric air masses with characteristics that evolve on the synoptic time scale. Diurnal variations are associated with upslope flow and the transition from nighttime air above the marine trade inversion to marine boundary layer air during daytime. During easterly trade wind conditions, growth and decay of the boundary layer are largely conservative in a regional context but contribute ∼12% of the nighttime water vapor at Mauna Loa. Tropospheric moisture is associated with convective outflow and exchange with drier air originating from higher latitude or higher altitude. During the passage of a moist filament, boundary layer exchange is enhanced. Isotopic data reflect the combination of processes that control the water balance, which highlights the utility for baseline measurements of water vapor isotopologues in monitoring the response of the hydrological cycle to climate change.
Novelli, P. C., J. W. Elkins and L. P. Steele, (1991), The Development and Evaluation of a Gravimetric Reference Scale For Measurements of Atmospheric Carbon Monoxide, Journal of Geophysical Research-Atmospheres, 96, D7, 13109-13121, JD01108 Abstract We have prepared a set of 17 carbon monoxide (CO) reference mixtures for use in the calibration of measurements of atmospheric concentrations of this gas. The mixing ratios of these standards range from 25 to 1003 ppb (parts per billion by mole fraction) in zero natural air and are contained in 5.9-L, high-pressure aluminum cylinders. Carbon monoxide was measured using gas chromatography with a mercuric oxide detector. The concentration range of the standards is sufficient to cover that of the background troposphere and also that found in remote locations affected by anthropogenic activities. The low concentration standards were prepared by gravimetric methods using one of three high concentration standards as the parent. Two of the parents were prepared by gravimetric methods starting from high-purity (99.97%) CO to have concentrations of about 250 ppm (parts per million) CO. A total of 14 atmospheric level primary standards were prepared from these two parents. The third parent was a NIST SRM (National Institute of Standards and Technology, Standard Reference Material) having 9.7 ppm CO, from which three standards were prepared. Monitoring of CO levels in the primary standards, relative to natural air contained in 29.5-L high-pressure aluminum cylinders, suggests that the CO content of some primaries may be increasing at rates of between 1 and 2 ppb yr?1. The CO concentration scale defined by the gravimetric standards was used to calibrate a set of 10 secondary standards. The secondary standards are all contained in 29.5-L high-pressure aluminum cylinders and range in concentration from 35 to 200 ppb. Examination of the CO content in several of the oldest secondary standards indicates their CO concentrations have not changed relative to each other over the 2 years they have been studied. Comparison of the low concentration standards derived from the gravimetric parents to those prepared from the NIST SRM show no difference to within 1% between the two scales. We also compared our standards to commercially available, NIST-traceable, CO standards (approximately 0.5 and 1 ppm of CO in air). The concentrations assigned these standards by the manufacturer agreed to within 3% of concentrations we calculated referenced to our standard scale. In addition, we compared our concentration scale to a CO standard used at the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia. Intercomparison of a cylinder of natural air between our laboratory and CSIRO (which used a CO reference gas traceable to the standards of the Oregon Graduate Institute for Science and Technology, formerly the Oregon Graduate Center) indicated that the CO concentration determined for this air based upon our reference scale was approximately 25% greater than the concentration determined by CSIRO. Carbon monoxide concentrations determined in flask samples collected at Mauna Loa, Hawaii, referenced to this concentration scale, are compared to the earlier reports of CO levels at this location by Seiler et al. [1976] and Khalil and Rasmussen [1988].
Novelli, P. C., L. P. Steele and P. P. Tans, (1992), Mixing Ratios of Carbon Monoxide in the Troposphere, Journal of Geophysical Research-Atmospheres, 97, D18, 20731-20750, JD02010 Abstract Carbon monoxide (CO) mixing ratios were measured in air samples collected weekly at eight locations. The air was collected as part of the CMDL/NOAA cooperative flask sampling program (Climate Monitoring and Diagnostics Laboratory, formerly Geophysical Monitoring for Climatic Change, Air Resources Laboratory/National Oceanic and Atmospheric Administration) at Point Barrow, Alaska (71�N), Niwot Ridge, Colorado (40�N), Mauna Loa and Cape Kumakahi, Hawaii (19�N), Guam, Marianas Islands (13�N), Christmas Island (2�N), Ascension Island (8�S) and American Samoa (14�S). Half-liter or 3-L glass flasks fitted with glass piston stopcocks holding teflon O rings were used for sample collection. CO levels were determined within several weeks of collection using gas chromatography followed by mercuric oxide reduction detection, and mixing ratios were referenced against the CMDL/NOAA carbon monoxide standard scale. During the period of study (mid-1988 through December 1990) CO levels were greatest in the high latitudes of the northern hemisphere (mean mixing ratio from January 1989 to December 1990 at Point Barrow was approximately 154 ppb) and decreased towards the south (mean mixing ratio at Samoa over a similar period was 65 ppb). Mixing ratios varied seasonally, the amplitude of the seasonal cycle was greatest in the north and decreased to the south. Carbon monoxide levels were affected by both local and regional scale processes. The difference in CO levels between northern and southern latitudes also varied seasonally. The greatest difference in CO mixing ratios between Barrow and Samoa was observed during the northern winter (about 150 ppb). The smallest difference, 40 ppb, occurred during the austral winter. The annually averaged CO difference between 71�N and 14�S was approximately 90 ppb in both 1989 and 1990; the annually averaged interhemispheric gradient from 71�N to 41�S is estimated as approximately 95 ppb.
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Oltmans, S. J. and H. I. Levy, (1994), Surface ozone measurements from a global network, Atmospheric Environment, 28, 1, 9-24, doi:10.1016/1352-2310(94)90019-1 Abstract From a network of sites, primarily in the Atlantic and Pacific Ocean regions, measurements of the surface ozone concentration yield information on the seasonal, synoptic, and diurnal patterns. These sites, generally removed from the effects of local pollution sources, show characteristics that typify broad geographical regions. At Barrow, AK; Mauna Loa, HI; American Samoa; and South Pole, data records of 15�20 years show trends that in all cases are a function of season. This dependence on season is important in understanding the causes of the long-term changes. At Barrow, the summer (July, August, September) increase of 1.7% per year is probably indicative of photochemical production. At South Pole, on the other hand, the summer (December, January, February) decrease is related to photochemical losses and enhanced transport from the coast of Antarctica. At all the sites there is a pronounced seasonal variation. In the Southern Hemisphere (SH), all locations which run from 14 to 90�S show a winter (July� August) maximum and summer minimum. In the Northern Hemisphere (NH) most of the sites show a spring maximum and autumn minimum. At Barrow (70�N) and Barbados (14�), however, the maxima occur during the winter, but for very different reasons. At many of the sites, the transport changes associated with synoptic scale weather patterns dominate the day-to-day variability. This is particularly pronounced at Bermuda and the more tropical sites. In the tropics, there is a very regular diurnal surface ozone cycle with minimum values in the afternoon maxima early in the morning. This appears to result from photochemical destruction during the day in regions with very low concentrations of nitrogen oxides. At Niwot Ridge, CO, and Mace Head, Ireland, there is clear evidence of photochemical ozone production in the summer during transport from known regional pollution sources.
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Perry, K. D., T. A. Cahill, R. C. Schnell and J. M. Harris, (1999), Long-range transport of anthropogenic aerosols to the National Oceanic and Atmospheric Administration baseline station at Mauna Loa Observatory, Hawaii, Journal of Geophysical Research-Atmospheres, 104, D15, 18521-18533, Abstract Size-segregated measurements of aerosol mass and composition are used to determine the composition and seasonal variations of natural and anthropogenic aerosols at Mauna Loa Observatory (MLO) from 1993 through 1996. Although the springtime transport of Asian dust to MLO is a well-documented phenomenon, this study shows that fine anthropogenic aerosols, including sulfur, black carbon, and enriched trace metals such as As, Cu, Pb, and Zn, are also routinely transported to MLO each spring. It is estimated that at least one third of the sulfate measured at MLO during the spring is anthropogenic. In addition, indirect measurements indicate that the organic aerosol concentrations are often comparable to the sulfate concentrations. This study also combines size- and time-resolved aerosol composition measurements with isentropic, backward air-mass trajectories and gas measurements of 222Rn, CH4, CO, and CO2 to identify some potential source regions of the anthropogenic aerosols. Three types of long-range transport episodes are identified: (1) anthropogenic aerosols mixed with Asian dust, (2) Asian pollution with relatively small amounts of soil dust, and (3) biomass burning emissions from North America. This study shows that anthropogenic aerosols and gases can be efficiently transported to MLO from both Asia and North America during the spring.
Peterson, J. T., W. D. Komhyr, T. B. Harris and J. F. S. Chin, (1977), NOAA carbon dioxide measurements at Mauna Loa Observatory, 1974-1976, Geophysical Research Letters, 4, 9, 354-356, 10.1029/GL004i009p00354 Abstract The Geophysical Monitoring for Climatic Change program of NOAA's Environmental Research Laboratories has measured atmospheric carbon dioxide concentrations at Mauna Loa Observatory, Hawaii, continuously since June 1974. The measurements through 1976 have been analyzed for recent secular concentration changes and show a continuing increase of about 0.9 ppm/year.
Pfister, G.Pétron, G., (2005), Quantifying CO emissions from the 2004 Alaskan wildfires using MOPITT CO data, Geophysical Research Letters, 32, 11, , 10.1029/2005GL022995 Abstract Recent optical observations of aerosols in the upper stratosphere and mesosphere show significant amounts of extinction at altitudes above about 40 km where the stratospheric sulfate aerosol layer ends. Recent modeling of this region reveals that meteoritic smoke settling from the mesosphere and its interaction with the upper part of the sulfate aerosol layer is the origin of the observed extinction. Extinction in this region has major implications for the interpretation and analysis of several kinds of aerosol data (satellite and lidar). We compare observations from the SAGE II satellite and from NOAA's lidar located at Mauna Loa, Hawaii to extinction profiles derived from the Whole Atmosphere Community Climate Model (WACCM) coupled with the Community Aerosol and Radiation Model for Atmospheres (CARMA). Our results show that a major source of extinction exists in the region above about 30 km that must be addressed by all remote sensing instruments that have traditionally used the stratosphere above about 30 km as an aerosol free region to estimate the molecular component of their total extinction. It is also shown that meteoritic smoke not only contributes to but also becomes the dominant source of aerosol extinction above 35 km and poleward of 30 degrees in latitude, as well as above 40 km in the tropics. After addressing the concerns described here, current and past observations of this region could be reanalyzed to further our understanding of meteoritic dust in the upper stratosphere.
Pueschel, R.F., B.A. Bodhaine and B. Mendonca, (1973), The Proportion of Volatile Aerosols on the Island of Hawaii, Journal of Applied Meteorology, 12, 2, 308-315, doi:10.1175/1520-0450(1973)012<0308:TPOVAO>2.0.CO;2 Abstract Nephelometry, in conjunction with a tube furnace and an Aitken nuclei counter, has been applied to the investigation of the volatile component of the aerosol budget at Cape Kumukahi, Hilo. and Mauna Loa Observatory, Hawaii. It was found that heating of the incoming air sample resulted in a decrease in light scattering above 100C due to the loss of organics and other easily volatilized compounds, and a drastic increase in Aitken nuclei counts at temperatures above 150C in the presence of ammonium sulfate. In the marine aerosol, a decrease in light mattering at about 45C was observed which is probably due to the loss of moisture during the phase transition from droplet to crystal. A second decrease near 120C is probably caused by the volatilization of organics from the droplet aerosol. In heating to 150C, the amount of light-scattering decrease was found to depend on the air mass. On occasions when volcanic effluent was apparently present, an increase in Aitken nuclei was noted in the heated air. Total aerosol mass deduced from light-scattering measurements before heating was in good agreement with aerosol mass measurements determined by standard high-volume filter sampling techniques. The total amount of aerosols in the air mass above the trade inversion is comparable to the quantity found in the marine air man. After penetrating the trade inversion, however, the cation content of the air is significantly reduced and the aerosol volatility is increased.
Pueschel, R.F. and B. Mendonca, (1972), Sources of Atmospheric Particulate Matter on Hawaii, Tellus B, 24, 139-149, DOI: 10.1111/j.2153-3490.1972.tb01541.x Abstract Sources and advection of atmospheric particulate matter on the Island of Hawaii were assessed to properly evaluate the benchmark qualities of the air at the Mauna Loa Geophysical Observatory. A manually operated Gardner counter, a continually recording Aitken counter and a nephelometer were used to measure diurnal and long term trends of concentrations and light scattering coefficients of atmospheric particulate. Significant sources of aerosol particles result from combustion activities on the island, both man-made and volcanic. Volcanic effluent can penetrate the tradewind inversion when conditions are right and show up on long term Aitken counts at the Mauna Loa Observatory. The relative contribution of marine aerosols to the total particle population in the air masses over the island is small. The difference in concentration and the light scattering coefficient of particles in the air masses above and below the tradewind inversion are in the order of one magnitude or more.
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Quay, P., J. Stutsman, D. Wilbur, A. Snover, E. J. Dlugokencky and T. Brown, (1999), The Isotopic Composition of Atmospheric Methane, Global Biogeochemical Cycles, 13, 2, 445-461, 1998GB900006 Abstract Measurements of the 13C/12C, D/H and 14C composition of atmospheric methane (CH4) between 1988 and 1995 are presented. The 13C/12C measurements represent the first global data set with time series records presented for Point Barrow, Alaska (71�N), Olympic Peninsula, Washington (48�N), Mauna Loa, Hawaii (20�N), American Samoa (14�S), Cape Grim, Australia (41�S), and Baring Head, New Zealand (41�S). North-south trends of the 13C/12C and D/H of atmospheric CH4 from air samples collected during oceanographic research cruises in the Pacific Ocean are also presented. The mean annual ?13C increased southward from about ?47.7 � at 71�N to ?41.2 � at 41�S. The amplitude of the seasonal cycle in ?13C ranged from about 0.4 � at 71�N to 0.1 � at 14�S. The seasonal ?13C cycle at sites in tropical latitudes could be explained by CH4 loss via reaction with OH radical, whereas at temperate and polar latitudes in the northern hemisphere seasonal changes in the ?13C of the CH4 source were needed to explain the seasonal cycle. The higher ?13C value in the southern (?47.2 �) versus northern (?47.4 �) hemisphere was a result of interhemispheric transport of CH4. A slight interannual ?13C increase of 0.02�0.005 � yr?1 was measured at all sites between 1990 and 1995. The mean ?D of atmospheric CH4 was ?86�3 � between 1989 and 1995 with a 10 � depletion in the northern versus southern hemisphere. The 14C content of CH4 measured at 48�N increased from 122 to 128 percent modern between 1987 and 1995. The proportion of CH4 released from fossil sources was 18�9% in the early 1990s as derived from the 14C content of CH4.
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Reinsel, G. C., G. C. Tiao, A. J. Miller, D. J. Wuebbles, P. S. Connell, C. L. Mateer and J. Deluisi, (1987), Statistical analysis of total ozone and stratospheric Umkehr data for trends and solar cycle relationship, Journal of Geophysical Research Atmospheres, 92, D2, 2201-2209, 10.1029/JD092iD02p02201 Abstract We report on trend analysis of Dobson total ozone data through 1984 and stratospheric Umkehr profile ozone data through 1981, including an examination of the relationship between ozone and long-term solar cycle activity using the 10.7-cm solar flux data. The estimate of the overall global trend in total ozone during the period 1970�1984, with associated 95% confidence (two standard error) limits, is (?0.26 � 0.92)% per decade, which indicates no significant overall trend. Based on use of the 10.7-cm flux measurements, an overall estimate of the total ozone-solar flux relationship is (1.18 � 0.66)% change in total ozone from solar cycle minimum to maximum, which indicates a statistically significant positive relationship. Trend analysis of Umkehr data through 1981 yields statistically significant negative trends on the order of (?0.30 � 0.17)% per year in layers 7 and 8 (? 34�43 km), with Mauna Loa transmission data being used to account for volcanic aerosol effects on the Umkehr data. The analysis also indicates significant relationships between Umkehr data and solar flux in layers 6 and 7 (? 29�38 km) of (2.57 � 1.25)% and (3.40 � 2.16)% change, respectively, from solar cycle minimum to maximum, with no significant relationship detected in the higher layers 8 and 9 where the estimates are more variable. Comparison of these empirical estimates with theoretical model calculations is discussed. Trend analysis of Umkehr data using data through 1984 is not reported in this paper because of the severe impact of volcanic aerosols from El Chichon on the Umkehr measurements during 1982�1984, although further research on methods for adjustment of Umkehr data for aerosol effects during this period is continuing.
Ridley, B., J. Walega, G. H�bler, D. Montzka, E. Atlas, D. Hauglustaine, F. Grahek, J. Lind, T. Campos, R. Norton, J. Greenberg, S. Schauffler, S. J. Oltmans and S. Whittlestone, (1998), Measurements of NO x and PAN and estimates of O3 production over the seasons during Mauna Loa Observatory Photochemistry Experiment 2, Journal of Geophysical Research-Atmospheres, 103, D7, 8323-8339, 98JD00075 Abstract Measurements of peroxyacetyl nitrate (PAN) and NO x and a variety of other constituents were made over approximately 1-month-long intensives in the autumn of 1991 and the winter, spring, and summer of 1992 during the second Mauna Loa Observatory Photochemistry Experiment (MLOPEX 2). PAN and NO x in the free troposphere had maximum abundances in spring in concert with the well-known maximum in O3. The ratio of the spring to summer averages was a factor of 4.1 for PAN, a factor of 1.6 for O3, and only a factor of 1.4 for NO x . During most intensives, variations over periods of a few days to a week were often larger than the average seasonal amplitude. In free tropospheric air masses local to Hawaii, average PAN/NO x ratios were a maximum in winter through spring but in the range of 0.25�0.86 in all intensives. PAN decomposition is unlikely to be the major net source of NO x in local air masses in summer and fall. The low HNO3/NO x ratios determined during MLOPEX 1 were confirmed during MLOPEX 2. Intensive average ratios of 1.6�3.8 over the year are lower than some model predictions. Both the low ratio and the magnitude of NO x imply a shortcoming in our understanding of the transformations and sources of NO y constituents in the central Pacific, The 3- to 4-km altitude region near Hawaii was a net importer of O3, on average, over the year. The average net rate of production of O3 in free tropospheric air was near zero in winter, ?0.4 to ?0.8 ppbv/d in spring, ?1.4 ppbv/d in summer, and ?0.6 ppbv/d in autumn. Thus the spring maximum in O3 is not due to local photochemistry. We believe, as has been concluded from the long-term measurements of long-lived constituents by the Climate Monitoring and Diagnostics Laboratory, that the variation of ozone precursors over the year and on shorter timescales of a few days to a week is controlled predominantly by changes in long-range transport: more frequent sampling of higher-latitude and higher-altitude air masses in winter and spring versus more frequent sampling of well-aged air from lower altitudes and latitudes in summer and autumn.
Ridley, B.A. and E. Robinson, (1992), The Mauna Loa Observatory Photochemistry Experiment, Journal of Geophysical Research-Atmospheres, 97, D10, 10285-10290, 91JD00945 Abstract Concurrent measurements of selected odd nitrogen constituents, hydrocarbons, peroxides, organic acids, formaldehyde, and other species were made from May 1 to June 4, 1988, at the Mauna Loa Observatory. An introduction to the experiment and a description of some of its objectives are presented.
Rinsland, C.P., A. Goldman, F.J. Murcray, T.M. Stephen, N.S. Pougatchev, J. Fishman, S.J. David, R.D. Blatherwick, P. C. Novelli, N.B. Jones and B.J. Connor, (1999), Infrared solar spectroscopic measurements of free tropospheric CO, C2H6, and HCN above Mauna Loa, Hawaii: Seasonal variations and evidence for enhanced emissions from the Southeast Asian tropical fires of 1997-1998, Journal of Geophysical Research-Atmospheres, 104, D15, 18667-18680, JD900366 Abstract High spectral resolution (0.003 c-1) infrared solar absorption measurements of CO, C2H6, and HCN have been recorded at the Network for the Detection of Stratospheric Change station on Mauna Loa, Hawaii, (19.5°N, 155.6°W, altitude 3.4 km). The observations were obtained on over 250 days between August 1995 and February 1998. Column measurements are reported for the 3.4-16 km altitude region, which corresponds approximately to the free troposphere above the station. Average CO mixing ratios computed for this layer have been compared with flask sampling CO measurements obtained in situ at the station during the same time period. Both show asymmetrical seasonal cycles superimposed on significant variability. The first 2 years of observations exhibit a broad January-April maximum and a sharper CO minimum during late summer. The C2H6 and CO 3.4-16 km columns were highly correlated throughout the observing period with the C2H6/CO slope intermediate between higher and lower values derived from similar infrared spectroscopic measurements at 32°N and 45°S latitude, respectively. Variable enhancements in CO, C2H6, and particularly HCN were observed beginning in about September 1997. The maximum HCN free tropospheric monthly mean column observed in November 1997 corresponds to an average 3.4-16 km mixing ratio of 0.7 ppbv (1 ppbv = 10-9 per unit volume), more than a factor of 3 above the background level. The HCN enhancements continued through the end of the observational series. Back-trajectory calculations suggest that the emissions originated at low northern latitudes in southeast Asia. Surface CO mixing ratios and the C2H6 tropospheric columns measured during the same time also showed anomalous autumn 1997 maxima. The intense and widespread tropical wild fires that burned during the strong El Nino warm phase of 1997-1998 are the likely source of the elevated emission products.
Russell, P. B., J. M. Livingston, E. G. Dutton, R. F. Pueschel, T. E. DeFoor, M. A. Box, D. Allen, P. Pilewskie, J. A. Reagan, B. M. Herman, S. A. Kinne and D. J. Hofmann, (1993), Pinatubo and Pre-Pinatubo optical depth spectra: Mauna Loa measurements, comparison, inferred particle size distributions, radiative effects, and Relationship to Lidar data, Journal of Geophysical Research-Atmospheres, 98, D12, 22969-22985, 93JD02308 Abstract The Ames airborne tracking sunphotometer was operated at the National Oceanic and Atmospheric Administration (NOAA) Mauna Loa Observatory (MLO) in 1991 and 1992 along with the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) automated tracking sunphotometer and lidar. June 1991 measurements provided calibrations, optical-depth spectra, and intercomparisons under relatively clean conditions; later measurements provided spectra and comparisons for the Pinatubo cloud plus calibration checks. June 1991 results are similar to previous MLO springtime measurements, with midvisible particle optical depth ?p(? = 0.526?m) at the near-background level of 0.012 � 0.006 and no significant wavelength dependence in the measured range (? = 0.38 to 1.06?m). The arrival of the Pinatubo cloud in July 1991 increased midvisible particle optical depth by more than an order of magnitude and changed the spectral shape of ?p(?) to an approximate power law with an exponent of about ?1.4. By early September 1991, the spectrum was broadly peaked near 0.5 ?m, and by July 1992, it was peaked near 0.8 ?m. Our optical-depth spectra include corrections for diffuse light which increase postvolcanic midvisible ?p values by 1 to 3% (i.e., 0.0015 to 0.0023). NOAA? and Ames Research Center (ARC)?measured spectra are in good agreement. Columnar size distributions inverted from the spectra show that the initial (July 1991) post-Pinatubo cloud was relatively rich in small particles (r<0.25?m), which were progressively depleted in the August-September 1991 and July 1992 periods. Conversely, both of the later periods had more of the optically efficient medium-sized particles (0.25<1 ?m) than did the fresh July 1991 cloud. These changes are consistent with particle growth by condensation and coagulation. The effective, or area-weighted, radius increased from 0.22 � 0.06?m in July 1991 to 0.56 � 0.12 ?m in August-September 1991 and to 0.86 � 0.29 ?m in July 1992. Corresponding column mass values were 4.8 � 0.7, 9.1 � 2.7, and 5.5 � 2.0 ?g/cm2, and corresponding column surface areas were 4.4 � 0.5, 2.9 � 0.2, and 1.1 � 0.1 ?m2/cm2. Photometer-inferred column backscatter values agree with those measured by the CMDL lidar on nearby nights. Combining lidar-measured backscatter profiles with photometer-derived backscatter-to-area ratios gives peak particle areas that could cause rapid heterogeneous loss of ozone, given sufficiently low particle acidity and suitable solar zenith angles (achieved at mid- to high latitudes). Top-of-troposphere radiative forcings for the September 1991 and July 1992 optical depths and size distributions over MLO are about ?5 and ?3 W m?2, respectively (hence comparable in magnitude but opposite in sign to the radiative forcing caused by the increase in manmade greenhouse gases since the industrial revolution). Heating rates in the Pinatubo layer over MLO are 0.55 � 0.13 and 0.41 � 0.14 K d?1 for September 1991 and July 1992, respectively.
Ryan, S, (1997), The wind field around Mauna Loa derived from surface and balloon observations, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102, D9, 10711-10725, Abstract The mountain wind field in the vicinity of Mauna Loa Observatory is derived by comparing vertical profiles of wind, ozone, and water vapor in the free troposphere to measurements made at the observatory. The wind field near the surface is described by two components: a radiation wind caused by the diurnal heating and cooling of the mountain slope, and a barrier wind caused by the free tropospheric wind flowing around the mountain barrier. The radiation wind is the primary factor in transporting air from different source altitudes in the free-troposphere to the observatory at 3400 m. At midday, air typically arrives from near the top of the marine boundary layer at 2500 m. After midnight, the average source altitude is 3400 m. The barrier wind field consists of a windward stagnation point, strong cross-slope and downslope flow in the flanks, and moderate downslope flow in the leeward sectors. The barrier wind field is effective at disrupting the surface temperature inversion and the radiation wind at night. A simple model is presented which relates the average properties and statistical variation of these winds to the vertical transport of air from the free troposphere to the observatory by the mountain wind field.
Ryan, S., (2001), Estimating Volcanic CO2 Emission Rates from Atmospheric Measurements on the Slope of Mauna Loa, CHEMICAL GEOLOGY, 177, 1-2, 201-211, Abstract The annual quiescent CO2 emissions from the summit of Mauna Loa volcano between 1959 and 1999 were calculated from atmospheric measurements made 6 km downslope at the Mauna Loa Observatory (MLO). Volcanic CO2 is trapped beneath a tens of meters thick temperature inversion at night and produces excess CO2 mixing ratios of up to tens of ppm above background. Measurements of the excess CO2, as a function of height above the ground, and wind direction are combined with the downslope wind speed to estimate the total flux of CO2 trapped near the ground, which provides a minimum estimate of the total volcanic emissions. The CO2 emissions were greatest shortly after each eruption and then decreased exponentially with 1/e time constants of 6.6, 6.5, and 1.6 years for the post-1950, 1975, and 1984 periods. Total emissions for these periods were 3.3, 1.9, and 2.5 x 10(8) kg, respectively. The distribution of quiescent volcanic CO2 with wind direction shifted eastward after the 1975 and 1984 eruptions by a few degrees, coinciding with a shift in eruptive activity from the SW rift (1950) to the NE rift (1984). A broadening of the distribution in 1993-1995 and 1998 is interpreted as indicating a new source high on the SW rift. Published by Elsevier Science B.V.
Ryan, S., E. J. Dlugokencky, P. P. Tans and M. Trudeau, (2006), Mauna Loa volcano is not a methane source: Implications for Mars, Geophysical Research Letters, 33, 12, L12301, doi:10.1029/2006GL026223 Abstract Thirteen years of continuous atmospheric carbon dioxide and methane measurements at the Mauna Loa Observatory in Hawaii are used to determine the methane emission rate from the summit of Mauna Loa volcano. We find no measurable methane emissions coming from the summit area, with a 95% confidence upper limit of 9 t CH4 yr?1. Recent studies have detected 10 ppb CH4 in the Martian atmosphere, requiring emissions of about 300 t CH4 yr?1. Volcanic activity has been suggested as a source of abiogenic CH4 on Mars, either by magmatic degassing or reactions in hydrothermal fluids heated by a magma intrusion. The most recent lava flows on Mars (2 My ago) are on the Tharsis shield volcanoes, which may still be active. If Mauna Loa is a valid terrestrial analog, our findings suggest that volcanic activity is not a significant source of methane to the Martian atmosphere.
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Schnell, R. C., (2005), 3. Trends in trace gases, Bulletin of the American Meteorological Society, 86, 6, S20-S23, Abstract From a global perspective, the annual average surface temperature in 2004 was the fourth highest value observed since regular instrumental records began in 1880. Global surface air temperatures in 2004 were 0.44 degrees C (0.79 degrees F) above the 1961-90 mean, according to both the U.S. and U.K. archives. Observations of the global annual mean temperature in 2004 from the combined lower and middle troposphere was 0.38 degrees C (0.68 degrees F)-the fourth warmest year in the 47-yr archive of worldwide radiosonde observations, and the ninth warmest year out of the past 26 based on satellite measurements. The average precipitation anomaly over global land areas in 2004 was 10.7 mm above average, which was similar to 1% above the 1961-90 mean, and the first year since 2000 that the global mean value was wetter than average. Northern Hemisphere sea ice extent was the third lowest on record for the year, dating back to 1973. The annual snow cover extent over Northern Hemisphere land areas was 25.1 million km(2), which was the 25th most extensive snow cover during the period of record. Levels of carbon dioxide (CO2) continue to increase in the atmosphere at the NOAA/Climate Modeling and Diagnostics Laboratory (CMDL) Mauna Loa Observatory on the Big Island of Hawaii; CO2 rose approximately 1.3 parts per million (ppm) in 2004, to reach a preliminary value of 377.6 ppm. However, the 2004 increase was below the long-term average increase of 1.5 ppm yr(-1). A minimum ozone concentration of 138 Dobson units (DU) was measured on 4 October 2004 at South Pole station, which was above the 1986-2004 average minimum value of 117 +/- 26 DU. Sea levels continued to rise globally, increasing at a rate of 2.8 +/- 0.4 mm yr(-1) based on satellite altimeter measurements. The satellite measurements since 1993 have recorded a significantly higher rise in sea level than the overall twentieth-century rate of 1.8 +/- 0.3 mm yr(-1), determined from tide gauge observations during the past century. The climate of 2004 was influenced by the development of a weak El Nino (i.e., ENSO warm event) in the western and central equatorial Pacific Ocean during the second half of the year. A series of westerly wind bursts during July-October, which were initiated by Madden-Julian oscillation activity in the tropical western Pacific, generated several Kelvin waves in the oceanic mixed layer that aided in the formation of the warm event. Only limited regional-scale impacts associated with El Nino occurred during the boreal autumn, because the event did not develop basinwide. Tropical cyclone activity was above average in the North Atlantic, west North Pacific, and South Indian Ocean basins in 2004. The hurricane season was extremely active in the North Atlantic basin, with a total of 15 named storms, nine hurricanes, and six major hurricanes in 2004. Nine of these tropical cyclones struck the Atlantic and Gulf of Mexico coasts of the United States, with three of these landfalling as major hurricanes. The first documented hurricane developed in the South Atlantic Ocean (cyclone ``Catarina''), which made landfall along the southern coast of Brazil in late March. The west North Pacific typhoon season was also very active, with 10 tropical systems making landfall in Japan, breaking the previous record of 6 during a single season. In the South Indian Ocean, Tropical Cyclone Gafilo devastated Madagascar, making landfall as a category 5 supercyclone. From a regional perspective, the annual mean temperature across Europe as a whole in 2004 was 0.98 degrees C above the 1961-90 base period average, with temperature anomalies in excess of 1 degrees C measured across parts of northwest Europe and Scandinavia. Temperatures were also warm across South America and parts of Asia. The annual average temperature in Russia was 0.8 degrees C above the long term mean, but temperatures in 2004 were anomalously cold in Asian Russia. Drought conditions continued across western North America, although conditions improved in the southwest United States and California late in the year, while the multiyear drought persisted in parts of the Pacific Northwest and Northern Rockies. Drought conditions also persisted across a majority of the Greater Horn and southern Africa. Monsoonal rains were deficient across the Indian subcontinent in 2004; only 87% of the long period average rainfall was recorded. In contrast, above-normal rainfall across parts of Southwest Asia helped ease some of the long-running drought conditions in the region.
Schnell, R. C., (2005), 5. Polar climate, b. Antarctic, II) Stratospheric ozone, Bulletin of the American Meteorological Society, 86, 6, S43-S44, Abstract From a global perspective, the annual average surface temperature in 2004 was the fourth highest value observed since regular instrumental records began in 1880. Global surface air temperatures in 2004 were 0.44 degrees C (0.79 degrees F) above the 1961-90 mean, according to both the U.S. and U.K. archives. Observations of the global annual mean temperature in 2004 from the combined lower and middle troposphere was 0.38 degrees C (0.68 degrees F)-the fourth warmest year in the 47-yr archive of worldwide radiosonde observations, and the ninth warmest year out of the past 26 based on satellite measurements. The average precipitation anomaly over global land areas in 2004 was 10.7 mm above average, which was similar to 1% above the 1961-90 mean, and the first year since 2000 that the global mean value was wetter than average. Northern Hemisphere sea ice extent was the third lowest on record for the year, dating back to 1973. The annual snow cover extent over Northern Hemisphere land areas was 25.1 million km(2), which was the 25th most extensive snow cover during the period of record. Levels of carbon dioxide (CO2) continue to increase in the atmosphere at the NOAA/Climate Modeling and Diagnostics Laboratory (CMDL) Mauna Loa Observatory on the Big Island of Hawaii; CO2 rose approximately 1.3 parts per million (ppm) in 2004, to reach a preliminary value of 377.6 ppm. However, the 2004 increase was below the long-term average increase of 1.5 ppm yr(-1). A minimum ozone concentration of 138 Dobson units (DU) was measured on 4 October 2004 at South Pole station, which was above the 1986-2004 average minimum value of 117 +/- 26 DU. Sea levels continued to rise globally, increasing at a rate of 2.8 +/- 0.4 mm yr(-1) based on satellite altimeter measurements. The satellite measurements since 1993 have recorded a significantly higher rise in sea level than the overall twentieth-century rate of 1.8 +/- 0.3 mm yr(-1), determined from tide gauge observations during the past century. The climate of 2004 was influenced by the development of a weak El Nino (i.e., ENSO warm event) in the western and central equatorial Pacific Ocean during the second half of the year. A series of westerly wind bursts during July-October, which were initiated by Madden-Julian oscillation activity in the tropical western Pacific, generated several Kelvin waves in the oceanic mixed layer that aided in the formation of the warm event. Only limited regional-scale impacts associated with El Nino occurred during the boreal autumn, because the event did not develop basinwide. Tropical cyclone activity was above average in the North Atlantic, west North Pacific, and South Indian Ocean basins in 2004. The hurricane season was extremely active in the North Atlantic basin, with a total of 15 named storms, nine hurricanes, and six major hurricanes in 2004. Nine of these tropical cyclones struck the Atlantic and Gulf of Mexico coasts of the United States, with three of these landfalling as major hurricanes. The first documented hurricane developed in the South Atlantic Ocean (cyclone ``Catarina''), which made landfall along the southern coast of Brazil in late March. The west North Pacific typhoon season was also very active, with 10 tropical systems making landfall in Japan, breaking the previous record of 6 during a single season. In the South Indian Ocean, Tropical Cyclone Gafilo devastated Madagascar, making landfall as a category 5 supercyclone. From a regional perspective, the annual mean temperature across Europe as a whole in 2004 was 0.98 degrees C above the 1961-90 base period average, with temperature anomalies in excess of 1 degrees C measured across parts of northwest Europe and Scandinavia. Temperatures were also warm across South America and parts of Asia. The annual average temperature in Russia was 0.8 degrees C above the long term mean, but temperatures in 2004 were anomalously cold in Asian Russia. Drought conditions continued across western North America, although conditions improved in the southwest United States and California late in the year, while the multiyear drought persisted in parts of the Pacific Northwest and Northern Rockies. Drought conditions also persisted across a majority of the Greater Horn and southern Africa. Monsoonal rains were deficient across the Indian subcontinent in 2004; only 87% of the long period average rainfall was recorded. In contrast, above-normal rainfall across parts of Southwest Asia helped ease some of the long-running drought conditions in the region.
Shetter, R. E., C. A. Cantrell, K. O. Lantz, S. J. Flocke, J. J. Orlando, G. S. Tyndall, T. M. Gilpin, C. A. Fischer, S. Madronich, J. G. Calvert and W. Junkermann, (1996), Actinometric and radiometric measurement and modeling of the photolysis rate coefficient of ozone to O(D-1) during Mauna Loa observatory photochemistry experiment 2, Journal of Geophysical Research Atmospheres, 101, D9, 14631-14641, Abstract The in situ photolysis rate coefficient of O3 to O(1 D) has been measured at Mauna Loa Observatory using a new actinometric instrument based on the reaction Of O(1 D) with N2O and with a hemispherical radiometer. One minute averaged photolysis rate coefficients were determined with an overall uncertainty of approximately � 11% at the 1 ? level for the actinometer and � 15% at the 1 ? level for the radiometer. Over 120 days of data were collected with varying cloud cover, aerosol loadings, and overhead ozone representing the first set of long term measurements. Clear sky solar noon values vary between approximately 3.0 � 10?5 and 4.5 � 10?5 sec?1. Modeling of the photolysis rate coefficients was done using a discrete ordinate radiative transfer scheme and results were compared with the actinometric measurements. The quantum yields for O(1 D) production are reevaluated from existing data and reported here. The comparisons were done using the quantum yields for the photolysis of ozone recommended by DeMore et al. [1994], the newer evaluation of Michelsen et al. [1994], and also with reevaluated values in this paper. An analysis of the measured photolysis rate coefficient of O3 to O(1 D) and model simulations of the photolysis rate coefficient data from clear days during the study provides added insight into the choice of quantum yield data for use in photochemical models of the troposphere.
Simpson, H.J., (1972), Aerosol Cations at Mauna Loa Observatory, Journal of Geophysical Research-Oceans, 77, 27, 5266-5277, doi:10.1029/JC077i027p05266 Abstract Aerosol and precipitation samples collected 3.4 km above sea level on the island of Hawaii have only 1% of the concentrations of Na that samples collected at sea level have. This difference suggests a short residence time for marine aerosols moving up the slopes of Mauna Loa. The major increase in the bulk chemistry of K, Ca, and Mg relative to Na occurs during the rapid loss of the first 90% of the aerosol mass. The chemistry of the remaining 'fractionated' aerosols resembles that of Hawaiian rain. A second population of aerosols, with substantially lower Na concentrations than fractionated marine aerosols, is present above the trade wind inversion. The major cation chemistry of these aerosols resembles that of continental rain.
Slusser, J., J. Gibson, D. Bigelow, D. Kolinski, W. Mou, G. Koenig and A. Beaubien, (1999), Comparison of Column Ozone Retrievals by use of an UV Multifilter Rotating Shadow-band Radiometer with those from Brewer and Dobson Spectrophotometers, Applied Optics, 38, 9, 1543-1551, doi:10.1364/AO.38.001543 Abstract The U.S. Department of Agriculture UV-B Monitoring Program measures ultraviolet light at seven wavelengths from 300 to 368 nm with an ultraviolet multifilter rotating shadow-band radiometer (UV-MFRSR) at 25 sites across the United States, including Mauna Loa, Hawaii. Column ozone has been retrieved under all-sky conditions near Boulder, Colorado (40.177 �N, 105.276 �W), from global irradiances of the UV-MFRSR 332- and 305-nm channels (2 nm FWHM) using lookup tables generated from a multiple-scattering radiative transfer code suitable for solar zenith angles (SZA�s) up to 90�. The most significant sources of error for UV-MFRSR column ozone retrievals at SZA�s less than 75� are the spectral characterizations of the filters and the absolute calibration uncertainty, which together yield an estimated uncertainty in ozone retrievals of ?4.0%. Using model sensitivity studies, we determined that the retrieved column ozone is relatively insensitive (
Slusser, J., J. H. Gibson, D. S. Bigelow, D. Kolinski, P. Disterhoft, K. Lantz and A. Beaubien, (2000), Langley Method of Calibrating UV Filter Radiometers, Journal of Geophysical Research Atmospheres, 105, D4, 4841-4849, Abstract The Langley method of calibrating UV multifilter shadow band radiometers (UV-MFRSR) is explored in this paper. This method has several advantages over the traditional standard lamp calibrations: the Sun is a free, universally available, and very constant source, and nearly continual automated field calibrations can be made. Although 20 or so Langley events are required for an accurate calibration, the radiometer remains in the field during calibration. Difficulties arise as a result of changing ozone optical depth during the Langley event and the breakdown of the Beer-Lambert law over the finite filter band pass since optical depth changes rapidly with wavelength. The Langley calibration of the radiometers depends critically upon the spectral characterization of each channel and on the wavelength and absolute calibration of the extraterrestrial spectrum used. Results of Langley calibrations for two UV-MFRSRs at Mauna Loa, Hawaii were compared to calibrations using two National Institute of Standards and Technology (NIST) traceable lamps. The objectives of this study were to compare Langley calibration factors with those from standard lamps and to compare field-of-view effects. The two radiometers were run simultaneously: one on a Sun tracker and the other in the conventional shadow-band configuration. Both radiometers were calibrated with two secondary 1000 W lamp, and later, the spectral response functions of the channels were measured. The ratio of Langley to lamp calibration factors for the seven channels from 300 nm to 368 nm using the shadow-band configuration ranged from 0.988 to 1.070. The estimated uncertainty in accuracy of the Langley calibrations ranged from �3.8% at 300 nm to �2.1% at 368 nm. For all channels calibrated with Central Ultraviolet Calibration Facility (CUCF) lamps the estimated uncertainty was �2.5% for all channels.
Stone, R. S., D. C. Douglas, G. I. Belchansky and S. D. Drobot, (2005), State of the Climate in 2004 3. Trends in trace gases, Bulletin of the American Meteorological Society, 86, 6, S39-S41, Abstract From a global perspective, the annual average surface temperature in 2004 was the fourth highest value observed since regular instrumental records began in 1880. Global surface air temperatures in 2004 were 0.44 degrees C (0.79 degrees F) above the 1961-90 mean, according to both the U.S. and U.K. archives. Observations of the global annual mean temperature in 2004 from the combined lower and middle troposphere was 0.38 degrees C (0.68 degrees F)-the fourth warmest year in the 47-yr archive of worldwide radiosonde observations, and the ninth warmest year out of the past 26 based on satellite measurements. The average precipitation anomaly over global land areas in 2004 was 10.7 mm above average, which was similar to 1% above the 1961-90 mean, and the first year since 2000 that the global mean value was wetter than average. Northern Hemisphere sea ice extent was the third lowest on record for the year, dating back to 1973. The annual snow cover extent over Northern Hemisphere land areas was 25.1 million km(2), which was the 25th most extensive snow cover during the period of record. Levels of carbon dioxide (CO2) continue to increase in the atmosphere at the NOAA/Climate Modeling and Diagnostics Laboratory (CMDL) Mauna Loa Observatory on the Big Island of Hawaii; CO2 rose approximately 1.3 parts per million (ppm) in 2004, to reach a preliminary value of 377.6 ppm. However, the 2004 increase was below the long-term average increase of 1.5 ppm yr(-1). A minimum ozone concentration of 138 Dobson units (DU) was measured on 4 October 2004 at South Pole station, which was above the 1986-2004 average minimum value of 117 +/- 26 DU. Sea levels continued to rise globally, increasing at a rate of 2.8 +/- 0.4 mm yr(-1) based on satellite altimeter measurements. The satellite measurements since 1993 have recorded a significantly higher rise in sea level than the overall twentieth-century rate of 1.8 +/- 0.3 mm yr(-1), determined from tide gauge observations during the past century. The climate of 2004 was influenced by the development of a weak El Nino (i.e., ENSO warm event) in the western and central equatorial Pacific Ocean during the second half of the year. A series of westerly wind bursts during July-October, which were initiated by Madden-Julian oscillation activity in the tropical western Pacific, generated several Kelvin waves in the oceanic mixed layer that aided in the formation of the warm event. Only limited regional-scale impacts associated with El Nino occurred during the boreal autumn, because the event did not develop basinwide. Tropical cyclone activity was above average in the North Atlantic, west North Pacific, and South Indian Ocean basins in 2004. The hurricane season was extremely active in the North Atlantic basin, with a total of 15 named storms, nine hurricanes, and six major hurricanes in 2004. Nine of these tropical cyclones struck the Atlantic and Gulf of Mexico coasts of the United States, with three of these landfalling as major hurricanes. The first documented hurricane developed in the South Atlantic Ocean (cyclone ``Catarina''), which made landfall along the southern coast of Brazil in late March. The west North Pacific typhoon season was also very active, with 10 tropical systems making landfall in Japan, breaking the previous record of 6 during a single season. In the South Indian Ocean, Tropical Cyclone Gafilo devastated Madagascar, making landfall as a category 5 supercyclone. From a regional perspective, the annual mean temperature across Europe as a whole in 2004 was 0.98 degrees C above the 1961-90 base period average, with temperature anomalies in excess of 1 degrees C measured across parts of northwest Europe and Scandinavia. Temperatures were also warm across South America and parts of Asia. The annual average temperature in Russia was 0.8 degrees C above the long term mean, but temperatures in 2004 were anomalously cold in Asian Russia. Drought conditions continued across western North America, although conditions improved in the southwest United States and California late in the year, while the multiyear drought persisted in parts of the Pacific Northwest and Northern Rockies. Drought conditions also persisted across a majority of the Greater Horn and southern Africa. Monsoonal rains were deficient across the Indian subcontinent in 2004; only 87% of the long period average rainfall was recorded. In contrast, above-normal rainfall across parts of Southwest Asia helped ease some of the long-running drought conditions in the region.
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Tans, P. P., K. W. Thoning, W. P. Elliot and T. J. Conway, (1990), Error estimates to background atmospheric CO2 patterns from weekly flask samples, Journal of Geophysical Research-Atmospheres, 95, D9, 14063-14070, Abstract The precision and accuracy of trends and seasonal cycles of CO2, as determined from grab samples, was investigated. First, the statistical aspects of infrequent (weekly) sampling were studied by simulating, via a partially random procedure, parallel time series of CO2 flask samples. These simulated flask series were compared to the continuous analyzer records from which they had been derived. The second approach to studying the uncertainties of flask records was to compare real flask results with simultaneous hourly mean concentrations of the in situ analyzers at the Geophysical Monitoring for Climatic Change observatories at Point Barrow, Mauna Loa, Samoa, and the south pole. The latter comparisons emphasized experimental, rather than statistical, errors. The uncertainties and sampling biases depend on the site and on the period of averaging. For monthly means the uncertainty varies from 0.2 to 0.6 ppm (one standard deviation, parts per million by volume), being largest for Barrow. Sampling biases for monthly means at Barrow and Mauna Loa are significant, up to 0.5 ppm. Experimental errors are the dominant error source for annual averages, and spurious interannual variations can be up to 0.4 ppm.
Thompson, T. M. and S. K. Cox, (1982), Subtropical climatology of direct beam solar radiation, Journal of Applied Meteorology, 21, 3, 334-338, 10.1175/1520-0450(1982)021<0334:SCODBS>2.0.CO;2 Abstract A climatology of direct beam irradiance has been compiled for Mauna Loa Observatory. A broadband transmittance, calculated from the direct-beam data, has been stratified into clear sky and optically thin and thick cloud regimes; statistics of this stratification may represent a means of monitoring possible climate change. We have shown how direct beam irradiance observations may be used to infer a climatology of optically thin cloudiness. These techniques have been applied to a five-year data set from Mauna Loa Observatory. Clear sky frequency of occurrence was 56% with a mean clear sky transmittance of 0.72. Clouds influenced the direct solar beam irradiance 44% of the time; this resulted in a mean transmittance of 0.49. Clear skies exhibited an annual cycle with less direct beam attenuation in the winter months. Although no trends in optically thin cloudiness were apparent in the five-year data set, the variability of the data allows one to estimate the length of record required to detect a given magnitude trend. For example, trends of 0.1 and 1.0% per year would require monitoring times of 212 and 46 months, respectively. After removing zenith-angle dependence from the data through a vertical transformation, thin cloud occurrence is uniformly distributed between the 0.12-0.60 transmittance range.
Thoning, K. W., (1989), Selection of NOAA/GMCC CO2 data from Mauna Loa Observatory, NOAA Technical Memorandum, 173, 131, 1-26, Abstract This report describes the selection processes used by NOAA/GMCC for selecting background hourly average CO2 data from Mauna Loa Observatory. This selection involved three steps: a preliminary selection based on within hour variability of the CO2 analyzer on a strip chart recorder; an hour-to-hour concentration difference that rejects data which change by more than 0.25ppm from one hour to the next; and a selection based on residuals from a spline fit. Examples are shown for the 1985 data, with emphasis on January and August. Of a total of 8227 hourly averages available in 1985, 3838 values (46.7%) remain after final selection. Summer months have a larger percentage of data removed than winter months.
Thoning, K. W., P. P. Tans and W.D. Komhyr, (1989), Atmospheric Carbon Dioxide at Mauna Loa Observatory 2. Analysis of the NOAA GMCC Data, 1974-1985, Journal of Geophysical Research-Atmospheres, 94, D6, 8549-8565, JD094iD06p0854 Abstract The first 12 years (1974-1985) of continuous atmospheric CO2 measurements from the NOAA GMCC program at the Mauna Loa Observatory in Hawaii are analyzed. Hourly and daily variations in the concentration of CO2 due to local sources and sinks are described, with subsequent selection of data representing background concentrations. A digital filtering technique using the fast Fourier transform and low-pass filters was used to smooth the selected data and to separate the seasonal cycle from the long-term increase in CO2.The amplitude of the seasonal cycle was found to be increasing at a rate of 0.05 ± 0.02 ppm yr-1. The average growth rate of CO2 was 1.42 ± 0.02 ppm yr-1, and the fraction of CO2 remaining in the atmosphere from fossil fuel combustion was 59%. A comparison between the Mauna Loa continuous CO2 data and the CO2 flask sample data from the sea level site at Cape Kumukahi, Hawaii, showed that the amplitude of the seasonal cycle at Cape Kumukahi was 23% larger than at Mauna Loa, with the phase of the cycle at Mauna Loa lagging the cycle at Cape Kumukahi by about 1-2 weeks.
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Vömel, H., M. Fujiwara, M. Shiotani, F. Hasebe, S. J. Oltmans and J. Barnes, (2003), The behavior of the Snow White chilled-mirror hygrometer in extremely dry conditions, Journal of Atmospheric and Oceanic Technology, 20, 11, 1560-1567, doi: 10.1175/1520-0426(2003)020<1560:TBOTSW>2.0.CO;2 Abstract The Snow White hygrometer, made by Meteolabor AG, Switzerland, is a new chilled-mirror instrument using a thermoelectric Peltier cooler to measure atmospheric water vapor. Its performance under dry conditions is evaluated in simultaneous measurements using the NOAA/CMDL frost-point hygrometer at Boulder, Colorado; San Crist�bal, Gal�pagos Islands, Ecuador; Watukosek, Indonesia; and Mauna Loa Observatory, Hawaii. The Snow White exhibits a lower detection limit of about 3%�6% relative humidity, depending on the sensor configuration. This detection limit is determined by the temperature depression attainable by the thermoelectric cooler. In some cases, loss of frost-point control within layers with relative humidity below this detection limit caused inaccurate measurements above these dry layers, where the relative humidity was within the detection range of the instrument. The sensor does not operate in the stratosphere because of the large frost-point depression and the large potential for outgassing of water from the instrument box and the sensor housing. The instrument has some capabilities in the tropical tropopause region; however, the results are somewhat mixed.
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Walega, J.G., B.A. Ridley, S. Madronich, F.E. Grahek, J.D. Shetter, T.D. Sauvain, C.J. Hahn, J.T. Merrill, B.A. Bodhaine and E. Robinson, (1992), Observations of Peroxyacetyl Nitrate, Peroxypropionyl Nitrate, Methyl Nitrate and Ozone During the Mauna Loa Observatory Photochemistry Experiment, Journal of Geophysical Research-Atmospheres, 97, D10, 10311-10330, 91JD02288 Abstract Measurements of the title species were made during the Mauna Loa Observatory Photochemistry Experiment (MLOPEX) conducted between May 1 and June 4, 1988, at the Geophysical Monitoring for Climatic Change (GMCC) station at 3.4-km elevation on the Island of Hawaii. Diurnal changes in the organic nitrates primarily resulted from the transition between downslope flow (usually free tropospheric air) and upslope flow (marine boundary layer or a mix of marine boundary layer and free tropospheric air, both influenced by island sources of precursors) characteristic of the site. Longer term trends in the mixing ratios reflected changes in air mass origins from mid-latitudes to more tropical latitudes. The average mixing ratios in free tropospheric samples were peroxyacetyl nitrate (PAN, 17 pptv), peroxypropionyl nitrate (PPN, 0.3 pptv), methyl nitrate (MN, 4 pptv), and O3 (43 ppbv). The organic nitrates (PAN, PPN, MN) represent minor components of the total odd nitrogen budget at the site. In free tropospheric samples, PAN, PPN, and MN constituted average percentages of 7%, <1%, and 2% of total odd nitrogen. In more tropical air masses, MN could constitute as much as 10% of total odd nitrogen. A photochemical model is used to investigate the sensitivity of free tropospheric PAN to local precursor concentrations. The observed mixing ratios of PAN are also contrasted with measurements made at continental surface sites and during aircraft programs.

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