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Our Recent Papers
- Lau, N.-C., and J. J Ploshay, 2009: Simulation
of synoptic and sub-synoptic scale phenomena associated with the East
Asian summer monsoon using a high-resolution GCM. Monthly Weather Review, 137, 137-160.
- LinHo, L H., X Huang, and N.-C. Lau, 2008: Winter-to-spring transition in East Asia: A planetary-scale perspective of the South China spring rain onset. Journal of Climate, 21(13), 3081-3096.
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- Lau, N.-C., A. Leetma, and M. J. Nath, February 2008: Interactions
between the responses of North American climate to El Niño–La Niña and
to the secular warming trend in the Indian–Western Pacific Oceans. Journal of Climate, 21(3), 476-494.
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- Jiang, X, N.-C. Lau, I. Held, and J. J. Ploshay, January 2007: Mechanisms of the Great Plains low-level jet as simulated in an AGCM. Journal of the Atmospheric Sciences, 64(2), 532-547.
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- Lau, N.-C., A. Leetma, and M. J. Nath, 2006: Attribution of Atmospheric Variations in the 1997–2003 Period to SST Anomalies in the Pacific and Indian Ocean Basins. Journal of Climate, 19(15), 3507-3628.
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- Lau, N.-C., and M. J. Nath, 2006: ENSO Modulation of the Interannual and Intraseasonal Variability of the East Asian Monsoon—A Model Study. Journal of Climate, 19(18), 4508-4530.
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- Lau, N.-C., and B Wang, 2006: Interactions between the Asian monsoon and the El Nino/Southern Oscillation In The Asian Monsoon, Berlin, Praxis, 479-512.
- Wittenberg, A. T., A. Rosati, N.-C. Lau, and J. J Ploshay, 2006: GFDL's CM2 Global Coupled Climate Models. Part III: Tropical Pacific Climate and ENSO. Journal of Climate, 19(5), 698-722.
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- Tam, C-Y, and N.-C. Lau, 2005: The impact of ENSO on atmospheric intraseasonal variability as inferred from observations and GCM simulations. Journal of Climate, 18(12), 1902-1924.
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- Tam, C-Y, and N.-C. Lau, 2005: Modulation of the Madden-Julian Oscillation by ENSO: Inferences from observations and GCM simulations. Journal of the Meteorological Society of Japan, 83(5), 727-743.
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- Lau, N.-C., M. J. Nath, and H Wang, 2004: Simulations by a GFDL GCM of ENSO-related variability of the coupled atmosphere-ocean system in the East Asian monsoon region In East Asian Monsoon, C.-P. Chang, Ed., World Scientific Series on Meteorology of East Asia, 271-300.
- Alexander, M A., N.-C. Lau, and J D Scott, 2004: Broadening
the atmospheric bridge paradigm: ENSO teleconnections to the tropical
West Pacific-Indian Oceans over the seasonal cycle and to the North
Pacific in Summer In Earth's Climate: The Ocean-Atmosphere Interaction, Geophysical Monograph 147, Washington, DC, American Geophysical Union, 85-103.
- Free, M, and John R Lanzante, in press: Effect of volcanic eruptions on the vertical temperature profile in radiosonde data and climate models. Journal of Climate. 3/08.
Both
observed and modeled upper-air temperature profiles show the
tropospheric cooling and tropical stratospheric warming effects from
the three major volcanic eruptions since 1960. Detailed comparisons of
vertical profiles of Radiosonde Atmospheric Temperature Products for
Assessing Climate (RATPAC) and Hadley Centre Atmospheric Temperatures,
Version 2 (HadAT2) radiosonde temperatures with output from 6 coupled
GCMs show good overall agreement on the responses to the 1991 Pinatubo
and 1982 El Chichon eruptions in the troposphere and stratosphere, with
a tendency of the models to underestimate the upper tropospheric
cooling and overestimate the stratospheric warming relative to
observations. Furthermore, the level of maximum stratospheric volcanic
warming does not always correspond between models and observations. In
addition, models and observations show a large disagreement at 100 hPa
for Pinatubo in the tropics, where observations show essentially no
change, while models show significant warming of ~0.7 to ~2.6 K. This
difference occurs even in models that accurately simulate stratospheric
warming at 50 hPa. Most models overestimate the tropospheric cooling
effect of the 1963 Agung eruption in the tropics and underestimate it
in the Southern Hemisphere extratropics, but uncertainties in the
observations and the volcanic forcings make meaningful comparisons
difficult for that eruption. Overall, the Parallel Climate Model (PCM)
is an outlier in that it simulates more volcanic-induced stratospheric
warming than both the other models and the observations in most cases.
Results for all three eruptions are sensitive to the methods used to
remove ENSO effects. The cooling effect at the surface in the tropics
is amplified with altitude in the troposphere in both observations and
models, but this amplification is greater for the observations than for
the models. In contrast, amplification for the ENSO signal in the
models is more similar to that in the observations. Estimates of the
effect of the eruptions on temperature trends are dependent on the
method used and the choice of parameters for these methods. From 1979
to 1999 in the tropics, RATPAC shows a trend of less than 0.1 K/decade
at and above 300 hPa while the mean of the models used here has a trend
of more than 0.3 K/decade, giving a difference of ~0.2 K/decade. From
0.02 to 0.08 K/decade of this difference may be due to the influence of
volcanic eruptions, with the smaller estimate appearing more likely
than the larger. In the lower troposphere, none of the difference in
trends appears to be attributable to volcanic effects.
- Lanzante, John R., and M Free, October 2008: Comparison of radiosonde and GCM vertical temperature trend profiles: Effects of dataset choice and data homogenization. Journal of Climate, 21(20), 5417-5435.
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- Lanzante, John R., in press: Comment
on "Trends in the temperature and water vapor content of the tropical
lower stratosphere: Sea surface connection" by Karen H. Rosenlof and
George C. Reid. Journal of Geophysical Research. 5/08.
- Santer, B. D., P. W. Thorne, L. Haimberger, K. E. Taylor, T. M. L. Wigley, J. R. Lanzante, S. Solomon, M. Free, P. J. Gleckler, P. D. Jones, T. R. Karl, S. A. Klein, C. Mears, D. Nychka, G. A. Schmidt, S. C. Sherwood, and F. J. Wentz, October 2008: Consistency of modelled and observed temperature trends in the tropical troposphere. International Journal of Climatology, 28(13), 1703-1722.
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- Lanzante, John R., 2007: Diagnosis
of Radiosonde Vertical Temperature Trend Profiles: Comparing the
Influence of Data Homogenization versus Model Forcings. Journal of Climate, 20(21), 5356-5364.
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- Lanzante, John R.,
T C Peterson, F J Wentz, K Y Vinnikov, D J Seidel, C Mears, J R
Christy, C E Forest, R S Vose, P W Thorne, and N C Grody, 2006: What
do observations indicate about the changes of temperatures in the
atmosphere and at the surface since the advent of measuring
temperatures vertically? In Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences,
Karl, T R, S J Hassol, C D Miller, W L Murray, Eds, Washington, DC,
Climate Change Science Program/Subcommittee on Global Change Research, 47-70.
A
new data set containing large-scale regional mean upper air
temperatures based on adjusted global radiosonde data is now available
up to the present. Starting with data from 85 of the 87 stations
adjusted for homogeneity by Lanzante, Klein and Seidel, we extend the
data beyond 1997 where available, using a first differencing method
combined with guidance from station metadata. The data set consists of
temperature anomaly time series for the globe, the hemispheres, tropics
(30°N–30°S) and extratropics. Data provided include annual time series
for 13 pressure levels from the surface to 30 mbar and seasonal time
series for three broader layers (850–300, 300–100 and 100–50 mbar). The
additional years of data increase trends to more than 0.1 K/decade for
the global and tropical midtroposphere for 1979–2004. Trends in the
stratosphere are approximately -0.5 to -0.9 K/decade and are more
negative in the tropics than for the globe. Differences between trends
at the surface and in the troposphere are generally reduced in the new
time series as compared to raw data and are near zero in the global
mean for 1979–2004. We estimate the uncertainty in global mean trends
from 1979 to 2004 introduced by the use of first difference processing
after 1995 at less than 0.02–0.04 K/decade in the troposphere and up to
0.15 K/decade in the stratosphere at individual pressure levels. Our
reliance on metadata, which is often incomplete or unclear, adds
further, unquantified uncertainty that could be comparable to the
uncertainty from the FD processing. Because the first differencing
method cannot be used for individual stations, we also provide updated
station time series that are unadjusted after 1997. The Radiosonde
Atmospheric Temperature Products for Assessing Climate (RATPAC) data
set will be archived and updated at NOAA's National Climatic Data
Center as part of its climate monitoring program.
- Santer, B D., T M L Wigley, C Mears, F J Wentz, S. A. Klein, D J Seidel, K E Taylor, P W Thorne, M F Wehner, P J Gleckler, J S Boyle, W D Collins, K. W. Dixon, C Doutriaux, M Free, Q Fu, J E Hansen, G S Jones, R Ruedy, T R Karl, J. R. Lanzante, G A Meehl, V Ramaswamy, G Russell, and G A Schmidt, 2005: Amplification of surface temperature trends and variability in the tropical atmosphere. Science, 309(5740), 1551-1556.
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- Seidel, D. J., J. K. Angell, A. Robock, B. Hicks, K. Labitzke, J. R. Lanzante, J Logan, J. D. Mahlman, V. Ramaswamy, W. Randel, E. Rasmusson, R. Ross, and S. F. Singer, 2005: Jim Angell's contributions to meteorology. Bulletin of the American Meteorological Society, 86(3), 403-410.
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- Sherwood, S C., J. R. Lanzante, and C Meyer, 2005: Radiosonde daytime biases and late-20th Century warming. Science, 309(5740), 1556-1559.
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