A potential vorticity perspective on cyclogenesis over centre‐eastern South America
A potential vorticity perspective on cyclogenesis over centre‐eastern South America
复制标题
南美洲中东部气旋发生的位涡视角
DOI：
10.1002/joc.6644
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
H. Wernli
中科院分区：
文献类型：
--
作者：
N. Crespo;R. P. da Rocha;M. Sprenger;H. Wernli
本研究使用1979-2017年ERA中期再分析数据研究了上层位涡（PV）结构对南美洲中东部表面气旋生成的影响。在三个地区（阿根廷、乌拉圭和巴西东南部）确定了地面气旋，并量化了PV拖缆和PV截止与气旋发生事件同时发生的频率。有有趣的区域和季节性差异：在阿根廷，光伏流光主要发生在夏季的气旋，在乌拉圭和巴西东南部在夏季和冬季。在这三个地区，与气旋发生相关的PV流光最常出现在320 K，除了在巴西东南部的夏季，他们在340 K占主导地位。PV截止发生的频率低于PV流光在气旋，他们更经常发生在夏季比冬季在所有三个地区。三个区域的气旋生成动力学在一些重要方面存在差异。在阿根廷，环境是稍微斜压在夏季和成因发生在赤道入口下方的急流条纹。在这个季节，异常PV与PV拖缆是重要的，有利于上升的斜压环境，有助于表面气旋。类似的模式发生在夏季和冬季在乌拉圭的气旋，并在巴西东南部的冬季。在阿根廷的冬季，气旋发生位于一个喷流条纹的极向出口下方，上游有一个较弱的PV流光。在巴西东南部夏季，急流是远离发生区和气旋发生在一个更正压的环境。
This study investigates the influence of upper‐level potential vorticity (PV) structures on surface cyclogenesis in central‐eastern South America using 1979–2017 ERA‐Interim reanalysis data. Surface cyclones are identified in three regions (Argentina, Uruguay and SEBrazil) and it is quantified how often PV streamers and PV cutoffs co‐occur with cyclogenesis events. There are interesting regional and seasonal differences: in Argentina PV streamers occur mainly with cyclogenesis in summer, and in Uruguay and SEBrazil in both summer and winter. In the three regions, PV streamers associated with cyclogenesis occur most frequently at 320 K, except for summer in SEBrazil, where they predominate at 340 K. PV cutoffs occur with lower frequencies than PV streamers during cyclogenesis, and they occur more often in summer than in winter in all three regions. The dynamics of cyclogenesis differs among the three regions in some important aspects. In Argentina, the environment is slightly more baroclinic in summer and genesis occurs beneath the equatorial entrance of a jet streak. In this season, the anomalous PV associated with a PV streamer is important to favour ascent in the baroclinic environment contributing to surface cyclogenesis. Similar patterns occur for cyclogenesis in summer and winter in Uruguay, and in winter in SEBrazil. In Argentina during winter, cyclogenesis is located beneath the poleward exit of a jet streak, with a weaker PV streamer upstream. In SEBrazil during summer, the jet stream is far displaced from the genesis region and cyclogenesis occurs in a more barotropic environment.
影响因子：
8
作者：
U. Neu;M. G. Akperov;Nina Bellenbaum;R. Benestad;R. Blender;R. Caballero;A. Cocozza;H. Dacre;Yang Feng;K. Fraedrich;J. Grieger;S. Gulev;J. Hanley;T. Hewson;M. Inatsu;K. Keay;S. Kew;I. Kindem;G. Leckebusch;M. Liberato;P. Lionello;I. Mokhov;J. Pinto;C. Raible;M. Reale;I. Rudeva;M. Schuster;I. Simmonds;M. Sinclair;M. Sprenger;N. Tilinina;I. Trigo;S. Ulbrich;U. Ulbrich;Xiaolan L. Wang;H. Wernli
通讯作者：
U. Neu;M. G. Akperov;Nina Bellenbaum;R. Benestad;R. Blender;R. Caballero;A. Cocozza;H. Dacre;Yang Feng;K. Fraedrich;J. Grieger;S. Gulev;J. Hanley;T. Hewson;M. Inatsu;K. Keay;S. Kew;I. Kindem;G. Leckebusch;M. Liberato;P. Lionello;I. Mokhov;J. Pinto;C. Raible;M. Reale;I. Rudeva;M. Schuster;I. Simmonds;M. Sinclair;M. Sprenger;N. Tilinina;I. Trigo;S. Ulbrich;U. Ulbrich;Xiaolan L. Wang;H. Wernli