Influence of the 850 hPa WPSH Abnormality on Rainfall in Jianghuai Basin in Early Summer

[Objective]The research aimed to study influence of the 850 hPa WPSH abnormality on rainfall in Jianghuai basin in early summer.[Method]Based on NCEP/NCAR 2.5°×2.5° analysis data,by using composite analysis,correlation analysis,etc.,circulation and rainfall abnormalities were analyzed.Subtropical index related to geopotential height field,zonal wind field,precipitation rate,vertical velocity field and so on.Influence of the 850 hPa WPSH abnormality in early summer on rainfall in Jianghuai basin was discussed.[Result]850 hPa WPSH abnormality in early summer had important influence on rainfall in Jianghuai basin.When WPSH area was small in early summer,and ridge point was by east and north,there was no blocking high in Sea of Okhotsk area at 500 hPa height field,and pathway of the cold air at high latitude was by north.Low-pressure disturbance in plum rain frontal zone weakened,and East Asian summer monsoon circulation strengthened.Cold air in Jianghuai basin was weak,which caused less precipitation in Jianghuai basin.When WPSH area was big in early summer,and ridge point was by west and south,it was controlled by blocking high in Sea of Okhotsk area at 500 hPa height field.Low-pressure disturbance in plum rain frontal zone strengthened,and East Asian summer monsoon circulation weakened.Cold air in Jianghuai basin was strong,which caused more precipitation in Jianghuai basin.[Conclusion]The research played indicative role in precipitation abnormality in Jianghuai basin.