Agreement in late twentieth century Southern Hemisphere stratospheric temperature trends in observations and CCMVal-2, CMIP3, and CMIP5 models

Ozone-induced stratospheric cooling peaks during November at an altitude of approximately 100 hPa in radiosonde observations, with 1969 to 1998 trends in the range of -3.8 to -4.7 K/dec.

This stratospheric cooling trend is more than 50% greater than the previously estimated value of -2.4 K/dec, which suggested that the CCMs were overestimating the stratospheric cooling, and that the less complex GCMs forced by prescribed ozone were matching observations better. Corresponding ensemble mean model trends are 3.8 K/dec for the CCMs, -3.5 K/dec for the CMIP5 GCMs, and -2.7 K/dec for the CMIP3 GCMs. Accounting for various sources of uncertainty--including sampling uncertainty, measurement error, model spread, and trend confidence intervals--observations and CCM and GCM ensembles are consistent in this new analysis.