Causes of Abnormal Precipitation During the Heaviest Meiyu Rainfall Season in Guizhou since 2000
To reveal the causes of the abnormal precipitation during the heaviest Meiyu rainfall season in Guizhou since 2000,the Tianqing precipitation data is used to identify the years with heaviest rainfall in Meiyu season in Guizhou since 2000 and the precipitation characteristics.Furthermore,the NCEP/NCAR reanalysis data and FY-2G blackbody brightness temperature(TBB)data are adopted to diagnose the reasons for the abnormally more precipitation and the causes of extreme precipitation.The results are as follows:(1)In the Meiyu season of 2020,the accumulated precipitation in Guizhou was the second-highest since 1961,and 2020 was the year with most anomalous precipitation since 2000.The rainstorms were concentrated from early June to early July,with extreme precipitation intensities on June 23 rd and 29 th.(2)The frequent rainstorm processes and extreme rainstorms in Guizhou during the Meiyu season of 2020 were closely related to the general background of the Meiyu rainfall in the Yangtze-Huaihe River Basin.(3)During the Meiyu season of 2020,mesoscale low-vortex systems that influenced Guizhou occurred frequently,and mesoscale convective systems were very active.Most of these mesoscale systems were initially formed in the western part of Guizhou,and then developed and strengthened within the province,leading to rainstorm weather.Mesoscale convective complexes(MCCs)were the direct influencing systems for the extreme precipitation on June 23rd and 29th.(4)In the Meiyu season of 2020,the low-level jet stream was abnormally active,especially in the early and late days of late June and the late days of early July when three sustained and intense low-level jet streams occurred.This provided exceptionally abundant water vapor conditions for the three persistent and most widespread rainstorm processes,and extreme rainstorms during the Meiyu season.The research results are expected to provide a basis for further improving the forecasting of persistent heavy rain,flood-inducing rainstorms,and extreme rainstorms in the Meiyu season.