摘要
利用一种新的工具,多尺度子空间变换(MWT),以及基于MWT的局地多尺度能量与涡度分析(MS-EVA)与Lorenz循环诊断方法,对2009年1月中下旬平流层发生的一次强爆发性增温(SSW)事件的内在动力学过程进行了研究。首先用MWT将各个场重构于三个尺度子空间,即平均尺度、爆发性增温尺度(或SSW尺度)和天气尺度子空间上。结果表明,极地迅速增长的温度主要是由于SSW尺度子空间上极区内的斜压不稳定引起的正则传输(有效位能从平均尺度子空间传输到SSW尺度子空间)造成的,显著增加的有效位能(APE)转换到了SSW尺度子空间的动能(KE)中,加之快速增温前极区内正压不稳定引起的正则传输(动能从平均尺度子空间传输到SSW尺度子空间)的作用,共同导致了极夜急流的反转。
The Lorenz cycle diagnosis is a powerful approach to the understanding of the internal dynamics within atmospheric events.Local Lorenz cycle energetics,however,are mostly restrained from usage due to their ambiguity in transport-transfer separation.Recently,this issue has been resolved through the introduction of a newfunctional analysis tool,namely the multiscale windowtransform( MWT),and the resulting energy transfer is known as ca-nonical transfer.In the present study,using an MWT-based localized multiscale energetics analysis,and according to the resulting local Lorenz cycle diagnostics,the 2009 sudden stratospheric warming( SSW) is investigated so as to achieve an understanding of the underlying dynamics.The fields are first reconstructed onto three scale windows,i.e.mean window,sudden warming windowor SSW window,and synoptic window. It is observed that the explosive growth of temperature has an intrinsic dynamic origin;it is due to a strong baroclinic instability,which results in a large canonical transfer of available potential energy from the mean windowto the SSW window.The accumulated SSW-scale potential energy is then converted into SSW-scale kinetic energy,which,together with a barotropic instability prior to the warming,lead to the reversal of the night jet.
作者
徐芬
梁湘三
XU Fen;LIANG Xiangsan(School of Atmospheric Sciences,Nanjing University of Information Science&Technology,Nanjing 210044,China;School of Marine Sciences,Nanjing University of Information Science&Technology,Nanjing 210044,China)
出处
《大气科学学报》
CSCD
北大核心
2020年第2期336-346,共11页
Transactions of Atmospheric Sciences
基金
国家自然科学基金资助项目(41975064)
江苏省双创计划团队项目(2015)。
