Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

摘要: In order to improve the representation of ozone absorption in stratosphere MAECHAM5 general circulation model, spectral resolution shortwave radiation parameterization used model has been in- creased from 4 6 bands. Two 20-years simulations with have performed, one standard and other newly introduced param- eterization respectively, evaluate temperature dy- namical changes arising two different representa- tions radiative transfer. simulation increased eterization, a significant warming almost entire domain is reported. At summer stratopause tempera- ture increase about K alleviates cold bias present when scheme used. These results are consistent both previous validation offline clear-sky comparison performed current work discrete ordinate stream scattering line by radia- tive transfer model. The shows substan- tial reduction daily averaged heating rate (1-2 K/day cooling) that occurs for tion upper stratosphere, un- der range atmospheric conditions. Therefore, band considered be bet- ter suited than parameterization. Concerning dynamical response it found reported at induces stronger zonal mean winds middle at- mosphere. there- after appear produce feedback (cooling) polar winter (summer) mesosphere, caused an downward (upward) cir- culation hemisphere. addition, gen- eral spec- tral associated cloud optical properties result (0.5-1 K) moistening (3%-12%) tropical troposphere. By comparing these modeled differences works, appears so- lar contribute also