Abstract: Based on the monthly temperature and precipitation data in the upstream of the Yangtze River from 1980 to 2019, we revealed the spatial and temporal distribution characteristics and variation rules of meteorological and hydrological elements in the upstream of Yangtze River in the past four decades via unary linear regression, F trend test, water balance analysis, centroid identification and other methods. Results unveiled that: 1) The average annual temperature, average annual precipitation, and average annual evaporation in the upstream of Yangtze River showed a trend of gradual decline from the southeast to the northwest, and the average annual soil water storage variation differed greatly spatially. 2) Temperature in the upstream of Yangtze River climbed remarkably from 1980 to 2019, with a change rate of 0.39 ℃/(10 a). Annual precipitation as a whole changed rarely, and the increased area was mainly located above Shigu station of Jinsha River. The inclination rate of annual evaporation in upstream Yangtze River was 6.08 mm/(10 a), of which the upper and lower reaches of Shigu station of Jinsha River, Jialing River basin, and Minjiang-Tuojiang River basin witnessed obvious growth trend. Average annual soil water storage variation decreased slightly as a whole, with a change rate of -6.14 mm/(10 a). 3) The longitude and latitude inclination rate of temperature centroid in upstream Yangtze River was -0.03°/(10 a) and 0.01°/(10 a), respectively, and those of evaporation centroid was -0.04°/(10 a) and 0.02°/(10 a), respectively. The longitude inclination rate of the centroid of precipitation and water storage variation was -0.06°/(10 a) and -0.01°/(10 a), respectively. The spatial centroid of all meteorological and hydrological elements showed a trend of moving towards the northwest, which implied that the air temperature, precipitation, evaporation, and water storage all increased in the northwest from the perspective of spatial distribution.

Key words: hydrometeorological elements, water balance, spatial and temporal distribution, change trend, upper Yangtze River