Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere
B. D. Santer,1*
T. M. L. Wigley,2
C. Mears,3
F. J. Wentz,3
S. A. Klein,1
D. J. Seidel,4
K. E. Taylor,1
P. W. Thorne,5
M. F. Wehner,6
P. J. Gleckler,1
J. S. Boyle,1
W. D. Collins,2
K. W. Dixon,7
C. Doutriaux,1
M. Free,4
Q. Fu,8
J. E. Hansen,9
G. S. Jones,5
R. Ruedy,9
T. R. Karl,10
J. R. Lanzante,7
G. A. Meehl,2
V. Ramaswamy,7
G. Russell,9
G. A. Schmidt9
The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set. Other observations show weak, or even negative, amplification. These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.
1 Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
2 National Center for Atmospheric Research, Boulder, CO 80303, USA.
3 Remote Sensing Systems, Santa Rosa, CA 95401, USA.
4 National Oceanic and Atmospheric Administration (NOAA)/Air Resources Laboratory, Silver Spring, MD 20910, USA.
5 Hadley Centre for Climate Prediction and Research, UK Met Office, Exeter, EX1 3PB, UK.
6 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
7 NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08542, USA.
8 Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195, USA.
9 NASA/Goddard Institute for Space Studies, New York, NY 10025, USA.
10 NOAA/National Climatic Data Center, Asheville, NC 28801, USA.
* To whom correspondence should be addressed. E-mail: santer1{at}llnl.gov
