资源环境科技发展态势分析平台

The Mei-yu season (MYS) is one of the most important components of the East Asian rainy season. As the MYS rainfall is significantly uneven, determining its notable features is crucial to understanding/predicting the MYS precipitation. This study provided the first report on the historical rankings of the accumulated precipitation within different regions during extreme MYSs. It was shown that, in the extreme 2020 MYS, the area-averaged precipitation within/around the Sichuan Basin ranked first during a 70-yr period. For the first time, quantitative contributions of mesoscale vortices to the total precipitation of extreme MYSs were shown. It was found that, during the 2020 MYS, vortices accounted for up to 50% of the MYS’s duration within/around Sichuan Basin, and induced up to 90% of the total precipitation there. The abnormally active vortices in the 2020 MYS were the direct reason for the highest precipitation in the past 70 years within/around the Sichuan Basin.