多要素表征的东亚季风区准双周振荡特征  

Characteristics of QBWO over the East Asian Monsoon Region Presented by Different Elements

作　　者：李靖怡 王遵娅[2] 温敏[1] Li Jingyi;Wang Zunya;Wen Min(Suate Key Laboratory of Severe Weather.Chinese Academy of Meteorological Simaes,Beijing 100081;Natiomal Climate Ceuter,Baijing 100081)

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]国家气候中心,北京100081

出　　处：《应用气象学报》2020年第6期653-667,共15页Journal of Applied Meteorological Science

基　　金：国家重点研究发展计划(2016YFA0600602);国家自然科学基金项目(41775060)。

摘　　要：为评估不同要素对东亚季风区准双周振荡的表征能力,对大气向外长波辐射(OLR)、500hPa位势涡度、850hPa相对涡度、850hPa风场和750hPa比湿等要素的准双周振荡特征进行对比,发现各要素均能很好反映东亚季风区明显的准双周振荡时空特征。OLR及500hPa位势涡度、850hPa相对涡度、850hPa纬向风表征的准双周振荡呈明显的西北向传播特征,500hPa位势涡度、850hPa相对涡度、850hPa纬向风北传更强,北传速度更快。850hPa经向风的准双周振荡呈明显西移特征,北传弱,北传速度最慢。而750hPa比湿准双周振荡呈东南向传播。不同要素准双周振荡的强度略有差异,其中750hPa比湿与其他要素的差异大。总体而言,750hPa比湿不能较好地表现出东亚季风区准双周振荡活动特征,而其余要素能很好地表征东亚季风区大气准双周振荡,其中500hPa位势涡度和850hPa相对涡度准双周振荡特征一致性高。Different variables present discrepancy in characteristics of the quasi-biweekly oscillation(QBWO),which is a dominant sub-seasonal signal in the East Asian monsoon regime.However,there is limited investigation about similarities and differences in features of QBWO presented by varying variables.In order to fill this gap,adopting the empirical orthogonal function(EOF)and composite analysis,such variables as outgoing longwave radiation(OLR),500 hPa potential vorticity(PV),850 hPa relative vorticity,850 hPa zonal wind,850 hPa meridional wind and 750 hPa specific humidity are compared,regarding of the spatial-temporal distribution,intensity and propagation of QBWO over the East Asian monsoon region.It is found that all these variables show significant QBWO across the region with similar spatial and temporal variation.And the strongest QBWO is observed over the South China Sea(SCS)with all variables.QBWO in OLR propagates north-westward over the East Asian monsoon regime.Centres of active(suppressed)QBWO convection correspond to positive(negative)PV anomalies at 500 hPa level and cyclonic(anticyclonic)vortex at 850 hPa level.These circulations form a northwest-southeast tilted wave train.Two leading modes of QBWO in 500 hPa PV,850 hPa relative vorticity and 850 hPa zonal wind have greater meridional magnitude than those of OLR.QBWO in three variables also propagate north-westward,but spread faster to north.Oppositely,two leading modes of QBWO in 850 hPa meridional wind are characterized by the zonal dipole pattern and the westward propagation is evident.Actually,its speed of northward propagation is the slowest of all.Different from all others,QBWO in 750 hPa specific humidity propagates south-eastward,and variances explained by QBWO of 750 hPa specific humidity is the smallest.As for the intensity of QBWO,except for 750 hPa specific humidity,other variables have consistent inter-annual variation.Totally,affected by such complex physical processes as transformation of precipitation state,release of heat and so on,cha

关 键 词：多要素 大气准双周振荡 特征对比 

分 类 号：P425.42[天文地球—大气科学及气象学]