【摘要】 基于江淮地区逐日降水的低频分量将2020年梅雨期划分为6个阶段,采用全球大气环流三型分解方法研究各阶段大气环流的演变特征,揭示超强梅雨的形成机理.结果表明:经圈型环流在江淮地区引起的强烈大气上升运动是2020年超强梅雨形成的关键因素;强降水阶段,高空南亚高压和中高纬槽脊系统的相互作用引导北方冷空气不断南下;西太平洋副热带高压长期偏强、位置偏西北,驱动其西北侧的低空西南暖湿气流持续向江淮地区输送;高低层冷暖空气在江淮地区辐合,形成梅雨锋和强烈上升运动,引发多次强降水过程,导致2020年梅雨异常偏强.更多还原

【Abstract】 The Meiyu Period in 2020 was divided into six stages based on the low-frequency component of daily precipitation. Using the three-pattern decomposition of global atmospheric circulation, the evolution characteristics of atmospheric circulation in different stages were studied to reveal the formation mechanism of extreme Meiyu. Results show that the strong atmospheric upward movement caused by meridional circulation over the Yangtze-Huaihe region was the key factor for the formation of the extreme Meiyu in 2020. In the heavy precipitation phase, the interaction between the South Asia high and the trough ridge system in the middle and high latitudes guided the cold air from the north to the south continuously. The western Pacific subtropical high has been strong and located to the west/north for a long time, which drives the low-altitude warm and wet southwest air to the northwest of the west Pacific subtropical high to the Yangtze-Huaihe region. The cold and warm air of the upper and lower layers converged over the Yangtze-Huaihe region, forming the Meiyu front and strong atmospheric upward movement, leading to several heavy precipitation processes and the extreme Meiyu in 2020.更多还原