Abstract:

 With the intensification of global warming, changes of precipitation varied greatly in different regions of China in recent 50 years. In this study, spatiotemporal variations of precipitation were analyzed based on daily precipitation data from 32 ground meteorological observation stations in Yunnan Province from 1967 to 2016. The linear regression method and 5-year moving average method were used to analyze the temporal variation of precipitation. The MannKendall test and the moving ttest were used to detect the abrupt change of precipitation. The Morlet wavelet analysis was used to investigate the regularity of the periodic change. The spatial variation of precipitation was analyzed using the Kriging method. The effects of various terrain factors on spatial variation of precipitation were explored by combining generalized linear mixed model (GLMM) analysis and correlation analysis. Annual precipitation showed a fluctuant downward trend, with wet season accounting for 83% of the total. There were abrupt changes of precipitation in 1995 and 2002, with a sharp increase in 1995, and a sudden decrease in 2002. Three periods (i.e., 23 years, 12 years, and 4 years) of oscillations in annual precipitation were observed, in which expectant 23year is the main oscillation period. It was predicted that Yunnan will experience a transitional period from more to less precipitation in the next few years, although still immersed in a pluvial stage. The spatial distribution of precipitation was uneven in Yunnan Province. Precipitation was high in the southwest and southern Yunnan, and decreased progressively to the northeast and northwest. During wet seasons, the spatial distribution of precipitation was mainly determined by elevation. The amount of precipitation increased with decreasing altitude and formed a precipitation center in Jiangcheng in Southern Yunnan. During dry seasons, precipitation center was formed in Gongshan in the Northwest due to the coupling effect of terrain and airflow. Our results showed that the instability of precipitation has aggravated while the decline rate has increased remarkably in recent years, indicating an aridification trend in Yunnan, which provides basic data for regional climate change and disaster warning. Furthermore, our results are important for predicting regional hydrology, improving utilization efficiency of water resources, and making scientific decisions on drought mitigation.

Key words: climate change, temporal characteristics, spatial distribution, influencing factor, Yunnan Province.