基于降水量距平百分率的中国西南和华南地区的冬旱特征

Characteristics of winter drought in southwest-south China based on precipitation anomaly percentage

利用我国西南和华南地区131个测站近50a的降水资料和NECP资料,采用线性趋势分析、合成分析、小波分析、功率谱分析等方法,通过季尺度降水距平百分率将冬旱分为无旱、轻旱、中旱、重旱和特重旱5个级别,分析了近50 a我国西南和华南地区各级别干旱的空间分布及时间变化特征。结果表明:在这一区域中,每一个级别的干旱都有从东向西增多的分布趋势;重旱、特重旱集中出现在川西南—云南、广东南部;各级别干旱都无明显的气候趋势,1963年是干旱最重的年份,主要在云南、广东等地,其次是1969年、2009年、1974年,但2010年末期干旱面积增大,强度增强。各级别的干旱具有2~3 a的周期,特重旱年有显著的6 a周期;干旱频率高的地方连旱频率也高,连旱年数增多,分布范围减小。

By use of nearly 50 a precipitation data and NECP data of 131 stations in southwest and south China and linear trend analysis,synthesis analysis,wavelet analysis,as well as power spectrum anlysis methods,the winter drought was divided into no drought,light drought,medium drought,heavy drought and special heary drought five grades based on season-scaled precipitation anomaly percentage. The results show that: in this area,each grade of drought has strengthening tendency from east to west,heavy drought and special heavy drought areas concentrate in southwestern Sichuan-Yunnan,southern Guangdong. Each grade drought climate trends are not obvious. The year1963 was the heaviest year of drought in 50 years,followed by 1969,2009 and 1974. But at the end of 2010,drought area increased and the intensity strengthened. Each grade of drought has 2 ~ 3a period,special heavydrought has 6a significant period; In high frequency drought area,the consecutive drought frequency is also high.With the increase in the number of consecutive drought year,the distribution range is reduced.