Effect of zonal asymmetries in stratospheric ozone on simulated Southern Hemisphere climate trends

Stratospheric ozone is represented in most climate models by prescribing zonal-mean fields. We examine the impact of this on Southern Hemisphere (SH) trends using a chemistry climate model (CCM): multi-decadal simulations with interactive stratospheric chemistry are compared with parallel simulations using the same model in which the zonal-mean ozone is prescribed. Prescribing zonal-mean ozone results in a warmer Antarctic stratosphere when there is a large ozone hole, with much smaller differences at other times. As a consequence, Antarctic temperature trends for 1960 to 2000 and 2000 to 2050 in the CCM are underestimated when zonal-mean ozone is prescribed. The impacts of stratospheric changes on the tropospheric circulation (i.e., summertime trends in the SH annular mode) are also underestimated. This shows that SH trends related to ozone depletion and recovery are underestimated when interactions between stratospheric ozone and climate are approximated by an imposed zonal-mean ozone field. Citation: Waugh, D. W., L. Oman, P. A. Newman, R. S. Stolarski, S. Pawson, J. E. Nielsen, and J. Perlwitz (2009), Effect of zonal asymmetries in stratospheric ozone on simulated Southern Hemisphere climate trends, Geophys. Res. Lett., 36, L18701, doi:10.1029/2009GL040419.