Temporal and Spatial Features of Spring Precipitation in the Middle and Lower Reaches of the Yangtze River

Based on daily precipitation data from 41 stations in China and monthly NCEP/NCAR reanalysis data,this paper studies the temporal and spatial features of spring precipitation in the middle and lower reaches of Yangtze River.The results indicate that,over the past 50 years,the rainfall amount and the number of rainy day show a decreasing trend and the precipitation strength shows a decreasing trend in the east but an increasing trend in the west.The successive precipitation is mostly the 2-day precipitation.There is often successive and light precipitation to north of the Yangtze River,while independent strong precipitation often occurs to south of it.In recent 50 years,there is a trend of getting droughty in spring in the middle and lower reaches of the Yangtze River,which has a close relationship with the temperature descent in mid-and upper-troposphere.The temperature descent induces a cyclonic anomaly in high level in the east of China,which exerts negative effect on the occurrence of precipitation.