JGR , submitted, 2006.
Abstract
Simulations of the stratosphere from 1980 to 2000 from thirteen coupled chemistry-climate models (CCMs) are compared with each other and to observations. Comparisons of the temperature fields show that the models reproduce the global, annual mean temperature fairly well, but most CCMs still have a cold bias in winter-spring polar regions in the southern hemisphere. Most display the correct stratospheric response to wave forcing in the northern, but not in the southern hemisphere. Comparisons of simulations of methane, mean age of air, and the so-called water vapor "tape recorder," show a wide spread in the results, indicating differences in transport. However, for around half the models there is reasonable agreement with observations. In these models the mean age and tape recorder are generally better than reported in previous model comparisons. Comparisons of the water vapor and inorganic chlorine (Cly) fields also show a large inter-model spread. Differences in water vapor are primarily related to biases in the simulated tropical tropopause temperatures, and not transport. The spread in Cly, which is largest in the polar lower stratosphere, appears to be primarily related to transport differences. In general the amplitude and phase of the annual cycle in total ozone is well simulated apart from the Antarctic, where there are significant differences in the Antarctic ozone hole among the models and in comparison with observations. CCMs show a large range of ozone trends over the past 25 years and large differences in comparisons with observations. Global temperatures trends are in reasonable agreement with satellite and radiosonde observations and compared to the CCM results presented in this study most models that neglect changes in stratospheric ozone generally show significantly less cooling at 50 hPa between 1980 and 2000.
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