Elliptical diagnostics of stratospheric polar vortices
Elliptical diagnostics of stratospheric polar vortices
复制标题
平流层极涡的椭圆诊断
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
D. Waugh
中科院分区：
文献类型：
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作者：
D. Waugh
提出了一种基于长寿命示踪剂或位涡等值线的空间矩的诊断方法，使平流层极涡的结构和演化能够被简明地总结和量化。利用涡缘区内等高线的二阶和低阶空间矩，定义了等熵面上涡旋“等价椭圆”的面积、中心、纵横比和方位。通过研究这些椭圆诊断随时间和高度的变化，可以量化极地涡旋的时间演变和垂直结构。通过检查来自地球物理流体动力学实验室“SKYHI”大气环流模型的一氧化二氮数据，评估了诊断的有用性。诊断显示并量化了SKYHI模型中北极和南极涡旋之间的几个差异。与南极涡旋相比，北极涡旋移动得更远，通常更细长，垂直结构更复杂(涡旋中心和伸长随高度的变化都更大)。椭圆诊断还确定了模式中大尺度Rossby波破裂事件的发生，无论是在涡旋边缘还是在副热带。
Diagnostics based on the spatial moments of isopleths of a long‐lived tracer, or of potential vorticity, are presented that enable the structure and evolution of stratospheric polar vortices to be concisely summarized and quantified. The area, centre, aspect ratio and orientation of the ‘equivalent ellipse’ of the vortex, on an isentropic surface, are defined using the second‐ and lower‐order spatial moments of contours within the vortex‐edge region. By examining the variations of these ‘elliptical’ diagnostics with time and altitude, the temporal evolution and vertical structure of the polar vortices can be quantified. The usefulness of the diagnostics is assessed by examining nitrous oxide data from the Geophysical Fluid Dynamics Laboratory ‘SKYHI’ general‐circulation model. The diagnostics show, and quantify, several differences between the Arctic and Antarctic vortices in the SKYHI model. The Arctic vortex moves further off the pole, is generally more elongated, and has a more complicated vertical structure than the Antarctic vortex (with larger variations of both the vortex centre and elongation with height). The elliptical diagnostics also identify the occurrence of large‐scale Rossby‐wave breaking events, both at the vortex edge and in the subtropics, in the model.