摘要
本文以ERA5资料为参考,对比分析WACCM模式对北半球热带外平流层冬季逐月(12月—次年2月)温度和环流的模拟结果,重点探讨模式对十年际变化的模拟偏差,而后结合行星波活动探讨引起模拟偏差的动力原因。ERA5资料结果表明,1980—2000年北半球平流层冬季温度和纬向风的气候态逐月差异较小,但其十年际变化差异较大,表现为从12月暖弱极涡向次年2月冷强极涡的连续演变。WACCM基本能模拟出逐月的气候平均场,也能模拟出12月、2月近乎反向的平流层温度与环流变化,但其12月—次年2月的十年际变化显示出不连续性。进一步诊断发现,资料与模式行星波1波强度和1~3波沿极地波导传播有显著的逐月变化,这与平流层温度和纬向风的变化相匹配。WACCM模拟的1波强度、E-P通量及其散度的十年际变化表现为逐月不连续,相应地,其平流层温度和环流的十年际变化也表现为冬季内不连续。
tBy 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 2Oth 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.
作者
徐凡森
刘仁强
XU Fansen;LIU Renqiang(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD),Nanjing University of Information Science&Technology,Nanjing 210044,China;Anhui Meteorological Observatory,Hefei 230031,China)
出处
《气象科学》
2024年第6期1102-1110,共9页
Journal of the Meteorological Sciences
基金
广东省重点领域研发计划资助项目(2020B1111200001)
国家自然科学基金资助项目(41575040)。
关键词
平流层
模式评估
十年际变化
纬向风
行星波活动
stratosphere
model evaluation
decadal change
zonal wind
planetary wave activity
