In February 2019, a month-long persistent precipitation event occurred in the Yangtze-Huaihe River basin. The geopotential height field that affected the duration of this frontal rainfall was divided into a high-latitude part and a low-latitude part for analysis. In the high-latitude part, a two-wave structure led to quasi-stationary circulation, and the change of both the blocking high pressure and Arctic Oscillation phase caused cold air to invade South China continuously and changed the frontal position. In mid-to-low latitudes, the persistent precipitation showed quasi-biweekly oscillation characteristics. The so-called “subtropical high-precipitation-anticyclone” (SHPA) feedback mechanism blocked the circulation systems in the mid-to-low latitudes and provided a continuous supply of water vapor for precipitation. As for the effect of sea surface temperature, the western North Pacific anomalous anticyclone stimulated by El Niño strengthened the intensity of the southerly wind and provided support for the redevelopment of the anticyclone system in the SHPA feedback mechanism. The sea surface temperature anomaly in the South China Sea provided sensible heating for precipitation, and convergent rising airflow was conducive to the occurrence of precipitation. Additionally, the SHPA mechanism provides a reliable basis for the prediction of persistent precipitation in winter in the mid-to-low latitudes.

中文翻译：

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2019年2月长江-淮河流域持续降水归因分析

2019年2月，长江淮河流域发生了长达一个月的持续性降水事件。将影响本次锋面降雨持续时间的位势高度场分为高纬度部分和低纬度部分进行分析。在高纬部分，双波结构导致环流准平稳，阻塞高压和北极涛动相位的变化导致冷空气不断侵入华南并改变锋面位置。中低纬度地区持续降水呈现准双周振荡特征。所谓的“副热带强降水-反气旋”（SHPA）反馈机制阻断了中低纬度的环流系统，为降水提供了持续的水汽供应。在海面温度的影响方面，厄尔尼诺现象激发的北太平洋西部异常反气旋加强了南风强度，为SHPA反馈机制中反气旋系统的再开发提供了支持。南海海面温度异常为降水提供了显热加热，汇聚上升气流有利于降水的发生。此外，SHPA机制为中低纬度地区冬季持续降水的预测提供了可靠依据。南海海面温度异常为降水提供了显热加热，汇聚上升气流有利于降水的发生。此外，SHPA机制为中低纬度地区冬季持续降水的预测提供了可靠依据。南海海面温度异常为降水提供了显热加热，汇聚上升气流有利于降水的发生。此外，SHPA机制为中低纬度地区冬季持续降水的预测提供了可靠的依据。