HR: 09:10h
AN: A51F-08    [Abstracts]
TI: Coupled Chemistry Climate Model Simulations of Stratospheric Temperature for the Recent Past
AU: * Austin, J
EM: john.austin@noaa.gov
AF: NOAA Geophysical Fluid Dynamics Laboratory, PO Box 308, Princeton, NJ 08542-0308, United States
AB: Temperature results for the recent past from multi-decadal simulations of eleven coupled chemistry climate models are analysed using multi-linear regression including a trend, solar cycle and volcanic aerosol terms. The climatology of the models since 1980 is in good agreement with observations for the troposphere but diverge from each other and from observations in the stratosphere. Overall, the models agree better with observations than previous assessments. As a function of latitude and pressure, the simulated trends vary substantially from model to model, although all models show several consistent features. These include statistically significant cooling trends from about the lower stratosphere upwards in the low and middle latitudes. Several models have statistically significant cooling in the lower stratosphere over the polar region. The temporal variation in the global average temperature in the lower stratosphere indicates a clear increase during volcanic eruptions, superimposed on an overall cooling. The model responses to the volcanic aerosol varies by about a factor of two with several models substantially overpredicting the observed response during the 1980s and 1990s. The globally averaged temperature simulated by the models is generally in agreement with corrected satellite observations over much of their range. Model trend comparisons are also shown for the polar spring and illlustrate even larger inter-model differences. These differences are caused by different simulations of trends in planetary waves and ozone amounts, and illustrate the challenge of predicting ozone recovery in polar regions.
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0350 Pressure, density, and temperature
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting