Study on the variation of precipitation in the middle-lower reaches of the Yangtze River in recent 60 years

Based on daily precipitation data at 426 national stations in the middle and lower reaches of the Yangtze River from 1958 to 2017, the variation of precipitation during the recent 60 years is analyzed by linear trend analysis, EOF decomposition and fives precipitation characteristic variables. The results are as follows. (1) The linear trend rate of annual precipitation in the middle and lower reaches of the Yangtze River is 2.21 mm·a^-1, while the trend rate in summer is 2.03 mm·a^-1. Rainfall in winter increases slightly, while the precipitation in spring and autumn decreases slightly. (2) The linear trend rate of annual precipitation days is -0.46 d·a^-1. while the precipitation days in spring, autumn and winter are all decreased, and is flat in summer. (3) The precipitation intensity shows a weak upward trend. The high value centers of the precipitation intensity are in the east of Jiangxi province, the eastern part of Hubei province, and the southern edge of Anhui province. The precipitation intensity is the highest in summer, and the lowest in winter. The precipitation intensity has a weak increasing trend for all four seasons. (4) The high value center of the coefficient of variation of precipitation is located at the edge of northwestern of Anhui province and the highest value is 0.25. The center of its low value is located in the western part of Hunan and the lowest value is 0.14. The coefficient of variation of precipitation in spring is the lowest, stable in the whole summer, and the fluctuation is large in autumn and winter. (5) The area of the middle and lower reaches of the Yangtze River can be divided into three spatial distribution types with annual precipitation as the index, i.e., the regional consistent pattern of the middle and lower reaches of the Yangtze River, the spatial pattern where precipitation in the northern and southern regions of the middle and lower reaches of the Yangtze River varies inversely, and the spatial pattern where precipitation in the east and west regions of the middle and lower reaches of the Yangtze River varies inversely.