WACCM4对20世纪末12月—次年2月平流层十年际变化模拟的动力偏差OACSTPCD

By comparison with the ERA5 reanalysis,this study evaluated the WACCM modeling of extratropical temperature and circulation in the Northern Hemisphere stratosphere during winter months(December-January-February,DJF)at the end of the 20th century.Then this paper focused on the WACCM simulations for the stratospheric decadal changes(1990s minus 1980s)and,through diagnosing the planetary wave activity,detected the dynamic causes of model deviations.The climatological monthly mean temperature and zonal wind from ERA5 appear to have no evident variations in winter,but their decadal changes show a clear evolution from a relatively warm and weak polar vortex in December to a relatively cold and strong polar vortex in February.WACCM can reproduce the monthly mean climatology and the opposite decadal changes of temperature and circulation in December and February.However,the simulated monthly decadal changes show discontinuity during DJF.For both the reanalysis and WACCM modeling,the decadal changes in the strength of planetary wave with wavenumber 1 and in the propagation of planetary waves with wavenumbers 1-3 along the polar waveguide display significant monthly changes that match with the respective monthly changes in the temperature and zonal wind.However,the simulated mon-thly decadal changes by WACCM in the strength of wave 1 and in the E-P flux and its divergence of waves 1-3 show corresponding winter discontinuity to that shown in the stratospheric temperature and circulation.