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.

中文翻译：

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南美中东部地区回旋作用的潜在涡度观点

本研究使用1979-2017年ERA-中期再分析数据，研究了南美中东部上层潜在旋涡（PV）结构对表面回旋作用的影响。在三个地区（阿根廷，乌拉圭和巴西）确定了地面旋风，并量化了PV流光和PV截断与成环事件同时发生的频率。区域和季节之间存在有趣的差异：在阿根廷， PV拖缆主要发生于夏季的回旋发生，而夏季和冬季在乌拉圭和SEBrazil发生。在这三个区域中，与轮生相关的PV彩带最常出现在320 K处，除了夏季在巴西，在340 K时占主导地位。PV截止发生的频率比PV拖缆的发生频率低，并且在这三个地区中，夏季发生的频率均高于冬季发生的频率。在某些重要方面，三个区域之间的回生动力学不同。在阿根廷，夏季的斜压环境稍强一些，并且起源发生在喷射条纹的赤道入口下方。在这个季节中，与PV流光有关的异常PV对于在斜压环境中促进表面循环发生的上升至关重要。在乌拉圭的夏季和冬季，以及在SEBrazil的冬季，发生循环现象的模式相似。在阿根廷在冬季，回旋作用位于射流条纹的极向出口下方，上游的PV流光较弱。在夏季的SEBrazil中，射流远离成因区，并且回旋作用发生在更正压的环境中。