Changing characteristics and spatial differentiation of spring precipitation in Southwest China during 1961-2012

In this study,we analyze spring precipitation from 92 meteorological stations spanning between 1961 and 2012 to understand temporal-spatial variability and change of spring precipitation over Southwest China.Various analysis methods are used for different purposes,including empirical orthogonal function(EOF) analysis and rotated EOF(REOF) for analyzing spatial structure change of precipitation anomaly,and the Mann-Kendall testing method to determine whether there were abrupt changes during the analyzed time span.We find that the first spatial mode of the precipitation has a domain uniform structure;the second is dominated by a spatial dipole;and the third contains five variability centers.The 2000 s is the decade with the largest amount of precipitation while the 1990 s is the decade with the smallest amount of precipitation.The year-to-year difference of that region is large:the amount of the largest precipitation year doubles that of the smallest precipitation year.We also find that spring precipitation in Southwest China experienced a few abrupt changes:a sudden increase at 1966,a sudden decrease at 1979,and a sudden increase at 1995.We speculate that the spring precipitation will increase gradually in the next two decades.