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Past Highlights
July 2007
Regional-global model NO2 column density for comparison with satellite observations and inverse modeling of NOx emissions. With the help of collaborators from Dalhousie University and Harvard University, division scientists have developed a merged regional-global model NO2 column density for comparison with satellite observations. The global model (GEOS-Chem) contains a more detailed representation of the upper troposphere emissions and the exchange processes between the stratosphere and the troposphere. The more fine-grained horizontal resolution of the regional model (CMAQ) better captures the urban and rural gradients. The merged fields are highly correlated (0.78) with the satellite observations from SCIAMACHY over the eastern United States during the summer of 2004. This merged dataset can help users of the satellite data more readily separate the impacts of surface NO2 emissions and aloft biogenic sources.
Using these results, inverse calculations have been performed to estimate what NOx emission changes would be needed to bring the modeled NO2 columns and satellite data into better agreement. Three independent versions of the modeled NO2 columns were tested for the inverse calculations: comparing SCIAMACHY results directly with CMAQ predictions; enhancing CMAQ predictions with ICARTT observations for the upper troposphere; and enhancing CMAQ predictions with GEOS‑CHEM results for the upper troposphere. The results are significantly different for the three cases. Comparison to data collected by the SEARCH monitoring network during this period does not single out which results are more accurate, but instead highlights the level of uncertainty inherent in modeling the tropospheric column budget of NO2. A draft of a manuscript summarizing this work is being prepared. rob.pinder@noaa.gov, sergey.napelenok@noaa.gov
Air Quality Forecast Model Development, Testing, and Analysis. Analysis of daily surface level O3 forecast from experimental NAM-CMAQ forecast over the Continental United Sates was continued. Two modifications were introduced in the PREMAQ to correct errors: (1) a mesophyll resistance term was added in the calculation of the deposition velocities for NO, NO2, and CO, and (2) modifications were introduced in the plume-rise calculation to use the correct pressure field on the hybrid coordinate. The latter change had minimal impact on the representation of plume rise of point source emissions and subsequent predicted O3. However, the changes in the deposition velocity calculations for NO and NO2 resulted in widespread regional impacts on predicted O3 with a general enhancement of 2-3 ppb for the daily maximum 8-hour O3. The modification also resulted in enhancements in predicted ambient CO concentrations due to reduced deposition velocity. Operational readiness briefings on the Continental U.S. experimental forecast systems are planned for later this summer by the National Weather Service. jonathon.pleim@noaa.gov, rohit.mathur@noaa.gov, george.pouliot@noaa.gov
Bi-directional mercury exchange in the Community Multiscale Air Quality(CMAQ) model over surface waters. Natural emissions of gaseous elemental mercury, (GEM) are estimated to be as large as or larger than the total anthropogenic mercury emissions to the atmosphere. Measurements of dissolved gaseous elemental mercury concentrations in surface waters are higher than predicted by Henry’s constant. Air quality models currently parameterize the atmosphere-surface water exchange of mercury by eliminating the atmospheric deposition and characterizing the evasion process as a function of meteorological parameters and/or constant surface water dissolved GEM concentration. Recent flux chamber measurements indicate a seasonal pattern in the atmospheric – surface water exchange of mercury, correlating with incoming solar radiation during the summer and with wind intensity during the winter. A mass conservative and physically descriptive multimedia bidirectional mercury exchange model is being developed for CMAQ to capture these processes. The wind driven atmosphere—surface water mercury fluxes are being parameterized using a two-film turbulent diffusion model, and a surface water photo-reduction scheme is being developed to better capture the enrichment of surface water with dissolved GEM. Both of these processes require mercury concentrations in the surface waters and a dynamic surface media layer to simulate surface accumulation and depletion of mercury from deposition and evasion. These processes have been added to CMAQ jesse.bash@noaa.gov
Community Modeling and Analysis System (CMAS) 2007 Annual Conference: The agenda has been announced for the 6th Annual CMAS User’s Conference scheduled for October 1-3, 2007, at the Friday Center in Chapel Hill, NC. Papers from all facets of air quality modeling were submitted, including both platform and poster presentations. The focus for this year’s conference is a special session on “advances in understanding the sensitivity of air quality models to meteorological inputs.” It is expected that at least 20 papers addressing this topic will be developed into full articles for consideration of their publication in a special issue of Environmental Fluid Mechanics Journal. S.T. Rao will be the Guest Editor of this special issue. Other sessions include air quality model developments, emission inventory modeling and analyses, air quality forecasting, model evaluation and analysis, climate variability and air quality, integrated modeling systems for environmental decision support, and urban database development and air quality applications. CMAS will offer training in the use of the Community Multiscale Air Quality (CMAQ) model and the Sparse Matrix Operator Kernel Emission (SMOKE) model in conjunction with the conference. As of the beginning of August, 132 paper titles and abstracts had been submitted, and 145 participants had registered from 11 countries. Registration for attendance will remain open through the conference, although reduced registration rates continues only through September 4, 2007. Registration details, logistics, and other details are available on the Internet at http://www.cmascenter.org 
. william.benjey@noaa.gov, st.rao@noaa.gov
Development of suitable method for measurement of dry deposition of elemental and reactive gaseous mercury to coastal ecosystems. A collaborative measurement campaign between NOAA/ASMD and the University of Connecticut’s Department of Marine Science has been initiated. The objective of this two-year study is to develop and to evaluate suitable micro-meteorological flux techniques to measure elemental and reactive gaseous mercury and to provide high-quality speciated mercury flux measurements in the marine boundary layer. Relaxed eddy accumulation and modified Bowen ratio measurements of the elemental mercury, reactive gaseous mercury, CO2, and H2O fluxes will be taken at Avery Point, Connecticut during summer, 2008 and at the Narragansett Bay National Estuarine Research Reserve during summer, 2009 The results of this measurement campaign, funded by the NOAA Cooperative Institute for Coastal and Estuarine Environmental Technology (CICEET), will provide the first micrometeorological measurements of speciated and elemental mercury loading to sensitive estuary systems. These measurements will support further development and evaluation of the bi-directional atmosphere-oceanic mercury exchange model for theCommunity Multiscale Air Quality (CMAQ). jesse.bash@noaa.gov
Measurement of the net exchange and in-canopy source/link characteristics of ammonia fluxes in an agricultural setting. ASMD scientists and an ORISE post doc collaborated with John T. Walker of the U.S. Environmental Protection Agency National Risk Management Research Laboratory and Tilden Meyers, LaToya Myles, and Laureen Gunter of the NOAA/ARL Air Turbulence and Diffusion Division in a USDA funded field measurement campaign at a 500 acre corn field in Lillington, North Carolina to investigate ammonia flux sources, sinks and regulation in a commercial agricultural setting. High-quality in- and above-canopy turbulence profiles, leaf temperature profiles, the in-canopy ammonia concentration gradient, and multiple measures of the atmospheric-canopy ammonia flux were collected throughout the growing season. Leaf and soil chemistry measurements were taken to better understand ammonia deposition over a wet canopy and the compensation point in the ammonia flux over a corn canopy. Two intensive studies were conducted from May 24 through June 4 (pre- and post- fertilization) and July 9 through July 15 (full canopy conditions). These data, in conjunction with detailed canopy turbulence and scalar exchange models, will be used to estimate the relative influence of canopy and soil sources/sinks on the overall atmospheric-canopy ammonia flux under a wide range of meteorological and ambient ammonia concentration conditions. The findings of this study will be used to evaluate and improve algorithms to predict the bi-directional exchange of ammonia from agricultural land cover types in the Community Multi-scale Air Quality model (CMAQ). jesse.bash@noaa.gov; donna.schwede@noaa.gov
SCIENTIFIC ACCOMPLISHMENTS
Chemical Mechanism Testing. The updated Carbon Bond (CB05) mechanism contains photolytic reactions for peroxyacetyl nitrate (PAN) and higher acylperoxy nitrate. However, the Statewide Air Pollution Research Center (SAPRC-99) mechanism does not contain any photolytic reactions for PAN and PAN analogues. To study the effects of such reactions on air quality, a special version of the SAPRC-99 mechanism was developed by adding four photolytic reactions for PAN and PAN analogues. Air quality model simulations using this modified version of the SAPRC-99 mechanism are being conducted. sarwar.golam@epa.gov
Documentation of the CMAQ-Hg Model. The Community Modeling and Analysis System (CMAS) documentation for the Community Multiscale Air Quality (CMAQ v4.6) model for mercury was updated to include additional information on the importance of including realistic emissions of mercury from natural processes in the model simulations. These emissions are required because CMAQ v4.6 simulates dry deposition of elemental mercury gas. This deposition flux is part of a bi-directional mercury exchange that remains poorly understood for most terrestrial surface types. Documentation of the process used during CMAQ v4.6 development to create emission inventories for natural and recycling mercury from land surfaces, oceans, and volcanic sources is also being developed and will be added to the CMAS documentation when it is completed. This additional documentation is being added after EPA/OAQPS experienced great difficulty in its first applications of the CMAQ multi-pollutant model. It is hoped that this additional documentation will aid the full CMAQ user community in performing atmospheric mercury simulations in the future. o.russell.bullock@noaa.gov
Evaluation of the University of California Davis aerosol module coupled to the Community Multiscale Air Quality model: A sectional aerosol model that dynamically simulates gas to particle conversion has recently been coupled to CMAQ; the CMAQ‑UCD model has been applied to simulate air quality in Tampa, Florida, during May 2002. The model has been evaluated against size‑segregated and chemically speciated aerosol measurements made at three Tampa‑area sites. Modeled total aerosol sulfate and ammonium concentrations and size distributions are in good agreement with measurements, but nitrate concentrations are biased low by a factor of two. Sea salt emissions are parameterized as a function of wind speed and relative humidity. Good agreement between measured and modeled sodium and chloride concentrations indicates that the model accurately predicts average emissions and advective transport of sea salt. A manuscript describing this work has been submitted to Atmospheric Environment. chris.nolte@noaa.gov
Inclusion of plume-rise calculations within CMAQ. Efforts are underway to incorporate the point source plume rise emissions processing from the SMOKE emissions processing system directly in the Community Multiscale Air Quality (CMAQ) model. This represents part of the steps toward coupling an in-line version of CMAQ directly into the meteorology driver model, namely the Weather Research Forecast (WRF) model. Successful unit testing for a non-parallel version has been completed. A suitable parallel version is under development. jeffrey.young@noaa.gov
Inter-comparison of Radiative Transfer Codes. An inter-comparison of radiative transfer codes for use in photolysis rate calculations for CMAQ is being performed. The current code used in the CMAQ pre-processor JPROC is being compared with the independent models MODTRAN and LibRadtran. Spectral actinic flux will be reported for several models tested under a matrix of independent variables, including solar zenith angle, altitude above ground level, visibility, total column ozone, and surface albedo. john.streicher@noaa.gov
Statistical modeling of the reaction probability for N2O5. Final editing of the manuscript, tables, and figures has been completed for this project. One major effort has been using CMAQ output to create example spatial plots of our final statistical model. A comparison of our model results to what has been previously published reveals that the spatial plots allow us to highlight many improvements in the new method for parameterizing the reaction probability. kristen.foley@noaa.gov
COMPUTER INFRASTRUCTURE SUPPORT
Programming Support for Data Fusion Methods Evaluation. Generated and assembled AQS, CASTNET, NAPS, and CMAQ modeled data needed to process fusion models. These data are needed to compare different techniques for merging modeled and observed data sets.steve.howard@noaa.gov
CONFERENCES, WORKSHOPS, AND PRESENTATIONS
Biogenic Secondary Organic Aerosols: Observations to Global Modeling, Hyytiala Forestry Field Station, Finland, July 1-4, 2007. Ann Marie Carlton was invited to attend this workshop in Finland, which is the first in a series of workshops for early career scientists from the United States and Nordic countries. The goals of the workshop are to improve research collaborations between the United States and Nordic scientists studying biogenic secondary organic aerosols (SOA), and to improve collaborations between scientists performing experiments/field observations with modelers to reduce uncertainty regarding the impact of biogenic SOA on atmospheric chemistry and climate. annmarie.carlton@noaa.gov
Community Outreach. Tanya Otte and Brian Eder represented the Division at a signing of a Memorandum of Understanding (MOU) with the North Carolina Museum of Life and Science in Durham, North Carolina, July 23, 2007. The focus of the MOU is to work together to raise the scientific literacy for various age groups in the local area. The MOU provides a formal mechanism for Federal employees at the EPA’s Research Triangle Park campus to serve as subject matter experts and guest speakers for the Museum’s indoor, outdoor, and web-based exhibits and modules. In addition, the MOU allows the Museum staff to improve and broaden science outreach to various age groups. The MOU will expire in five years. tanya.otte@noaa.gov, brian.eder@noaa.gov
SMOKE Training. Adam Reff completed a modeling training course entitled, “Introduction to SMOKE,” held by the Community Modeling and Analysis System (CMAS), Chapel Hill, North Carolina, July 23-25, 2007. The course involved learning to use the Sparse Matrix Operating Kernel for Emissions (SMOKE) modeling system to create model-ready emissions files from raw inventory data. reff.adam@epa.gov
Wisconsin Natural Resources Board (NRB) on Atmospheric Mercury Deposition Modeling, Wisconsin Department of Natural Resources, Stevens Point, Wisconsin, July 18, 2007. Russ Bullock was invited to attend this mercury seminar, and gave a presentation entitled “Atmospheric Mercury Deposition: Overview of Source Attribution.” The NRB wanted to learn more about the modeling used by the Environmental Protection Agency during the development of its Clean Air Mercury Rule, and what the current modeling science can say specifically about the sources of mercury deposition to the State of Wisconsin. o.russell.bullock@noaa.gov
Workshop of VOC Exposure Modeling. The American Chemistry Council Long-Range Research Initiative (ACCLRI) sponsored a workshop on volatile organic compound (VOC) exposure modeling at the Computational Chemodynamics Laboratory, Rutgers University on June 20, 2007. The Workshop focused on the current state and future directions of methods and data for modeling human exposures to volatile organic compounds (VOCs) across multiple scales (regional to local to neighborhood to personal). Research directions and needs in VOC inhalation exposure modeling in a source-to-dose-to-effect framework were presented by the Environmental and Occupational Health and Statistics Institute (EOHSI) team. Presentations also included VOC inhalation exposure modeling and database activities and U.S. Environmental Protection Agency and New Jersey Department of Environmental Protection. Jason Ching’s invited paper was “Employing Sub-Grid Variability (SGV) properties of Air Quality models towards improving exposure assessments.” A website containing the Workshop presentations can be found at http://ccl.rutgers.edu/abstracts.htm#2007 . jason.ching@noaa.gov
VISITORS
Professor Leon Hardy of the Department of Mathematics at North Carolina Central University brought a group of about 15 high school juniors and seniors to the Fluid Modeling Facility for a tour of the laboratory and a demonstration of dispersion around buildings and roadway in the wind tunnel. The students were part of the Summer Ventures program designed to expose high school to science and mathematics. Steven.perry@noaa.gov; david.heist@noaa.gov
A group of five Japanese scientists representing several industry groups who are collectively developing an advanced plume model for regional impact visited the Atmospheric Sciences Modeling Division (ASMD) and the Office of Air Quality Planning and Standards (OAQPS) in Research Triangle Park, North Carolina on Monday, July 9, 2007 to discuss model development and evaluation plans. They have developed an advanced meso-to-local scale model for application to the permitting of future power stations. A seminar entitled “Model Development to Simulate the Mesoscale Meandering Effects of Wind Fluctuations on Horizontal Gas Diffusion Over Mt. Tsukuba, near Tokyo, Japan” was presented by Ryohii Ohba Nagasaki, R&D Center, Mitsubishi Heavy Industries, Ltd, Nagasaki, Japan. Alan.huber@noaa.gov
Dr. Pieternal F.Levelt from the Royal Netherlands Meteorological Institute and Dr. P.K. Bhartia from NASA Goddard Space Flight Center visited the Division on July 11, 2007 to discuss potential collaborations on the use of the remote sensing information from the EOS-Aura Ozone Monitoring Instrument (OMI). Dr. Pieternel is the Principal Investigator of the OMI. Data products from the instrument include derived tropospheric products of NO2, SO2, HCHO, O3, and aerosol index daily at a spatial resolution of approximately 25 km x 25 km. rohit.mathur@noaa.gov, kenneth.schere@noaa.gov, alice.gilliland@noaa.gov
PUBLICATIONS
Published Papers
Irwin, J. S., W. B. Petersen, and S. Howard. Probabilistic characterization of atmospheric transport and diffusion. Journal of Applied Meteorology and Climatology (special issue), 46(7): 980‑993 (2007).
Gego, Edith, P, S. Porter, A. Gilliland, and S. T. Rao. Observation‑based assessment of the impact of nitrogen oxides emissions reductions on ozone air quality over the eastern United States. Title changed from An examination of the impact of the reductions in nitrogen oxides emissions on ozone air quality over the eastern United States. Journal of Applied Meteorology and Climatology (special issue), 46(7): 994‑1008 (2007).
Yu, S., P. V. Bhave, R. L. Dennis, and R. Mathur. Seasonal and regional variations of primary and secondary organic aerosols over the continental United States: Observation-based estimates and Model evaluation, Environmental Science & Technology 41: 4690 - 4697.
Web Publication
Kleindienst, T.E., M. Jaoui,M. Lewandowski, J.H. Offenberg, C.W. Lewis, P.V. Bhave, and E.O. Edney. Estimates of the contributions of biogenic and anthropogenic hydrocarbons to secondary organic aerosol at a southeastern U.S. location, Atmospheric Environment. Web publication date: July 5, 2007.
Papers in Press
Mathur, R., S. Yu, D. Kang, and K. Schere. Assessment of the Winter-time performance of developmental particulate matter forecasts with the Eta-CMAQ modeling system, Journal of Geophysical Research-Atmospheres, 2007.
Tong, D., R. Mathur, K. Schere, D. Kang, and S. Yu. The use of air quality forecasts to assess impacts of air pollution on crops: Methodology and case study, Atmospheric Environment, 2007.
Papers in Journal Review
Godowitch, J.M., A.B. Gilliland, R.R. Draxler, S.T. Rao, 2007.Modeling assessment of point source NOx emission reductions on ozone air quality in the eastern United States. Atmospheric Environment.
Luecken, D.J. Technical challenges involved in implementation of VOC reactivity-based control of ozone, submitted to Environmental Science and Technology, May 3, 2007.
Luecken, D.J. and A.J. Cimorelli. Co-dependencies of reactive Air Toxic and criteria pollutants on emission reductions, submitted to Journal of Air and Waste Management Association, March 22, 2007.
Submitted Papers
Luecken, D.J., Phillips, S., Sarwar, G., Jang, C. Effects of using the CB05 vs. SAPRC99 vs. CB4 chemical mechanism on model predictions: ozone and gas-phase photochemical precursor concentrations, submitted to Atmospheric Environment, (special issue on International Conference on Atmospheric Chemical Mechanisms) July 3, 2007.
Hutzell, W. and D.J. Luecken. Transport and Fate of emissions for several toxic metals over the United States, submitted to Science of the Total Environment, July 2007.
Papers in NOAA Review
Gilliland, A.B., C. Hogrefe, R.W. Pinder, J.M. Godowitch, S.T. Rao, 2007. Dynamic Evaluation of Regional Air Quality Models: Assessing Changes in O3 Stemming from Changes in Emissions and Meteorology, To be submitted to Atmospheric Environment in August.
Godowitch, J.M., C. Hogrefe, A.B. Gilliland, S.T. Rao, 2007. Influence of point source NOx emission reductions on modeled processes governing ozone concentrations and chemical / transport indicators. To be submitted to Journal of Geophysical Research.
Highlights