Characteristics of Anomalous Sign and Prediction of Summer Precipitation in the Middle Reaches of Yellow River

Using 61 station precipitation data in the middle reaches of Yellow River,characteristics and ambient field of summer precipitation in the middle reaches of the Yellow River are analyzed and one prediction model is established in this paper.The research result reveales that summer precipitation in the middle reaches of Yellow River is mainly affected by the East Asian jet stream,the West Pacific subtropical high and the low trough in the vicinity of Lake Baikal.That is,when the East Asian jet stream and the West Pacific subtropical high are stronger,lying more northward,and the Baikal trough is deeper,more rains fall in this region,and vice versa.Besides,the autumn Southern Oscillation,the North African subtropical high,the South China Sea subtropical high,the Northern Hemisphere subtropical high and the Northern Hemisphere polar vortex can all exert an impact on the summer circulation and precipitation in the middle reaches of Yellow River.Therefore,a forecast model for summer precipitation in the middle reaches of the Yellow River is established by using the above factors.Assessment shows that this model has good prediction ability and can be used for quantitative prediction of summer precipitation in the middle reaches of Yellow River.