关键词: 相对湿润度, 干旱, Morlet小波分析, 干季, 雨季, 气候变化

Abstract: Based on the monthly precipitation and temperature data from 15 meteorological stations in Yunnan during 1961-2010， the temporal and spatial variation of drought climate in Yunnan was analyzed by using relative moisture index （M index） and Morlet wavelet method. The results showed that the M index mainly reflected the effect of precipitation on drought during rainy season in Yunnan while the M index was responded to evapotranspiration which resulted from temperature and sunshine during dry season. There was big fluctuation on dry wet climate in Yunnan both from interannual and interdecadal change. M index mainly showed periodical changes with 10-16 years， 6-8 years and 2-4 years in rainy season while with 8 years and 4-6 years mostly appeared in dry season， and its regional change in rainy season was bigger than that in dry season. Most of the severe droughts in Yunnan showed similar trend， which was smaller M index value in last rainy season， lower index value in following dry season， and delaying rainy season in this year. The climate in rainy season was tending to dry， and climate in dry season tend to more dry under global warming. The main period of M index change in most region of Yunnan entered into low value stages， accompanying precipitation decline， which resulted in frequent severe droughts. The results could provide references for drought prediction and evaluation， and risk management in Yunnan

Key words: Relative moisture, Drought, Morlet wavelet analysis, Dry season, Rainy season, Climate Change