云南省1961—2012年干旱时空变化特征

Temporal and Spatial Characteristics of Droughts over Yunnan Province During 1961—2012

基于云南省126个气象站点1961—2012年逐月降水数据,采用标准化降水指数(SPI),分析年度和季节干旱强度、干旱频率以及干旱影响范围的时空变化特征。结果表明:1)年尺度上干旱强度呈增强的趋势。春季干旱强度减弱,夏、秋季干旱强度增强,冬季变化不明显;82%站点的干旱强度呈增强的趋势,其中滇东地区增强趋势最为显著。2)滇西北、滇中、滇东南及滇西南部分地区干旱发生频率较高,滇东和滇东北地区易出现极旱。春季干旱主要发生在滇西北、滇西地区;夏季干旱主要发生在滇西、滇西南地区;秋季干旱集中分布在滇西、滇西南、滇中和滇东北地区;而全省大部分地区冬季干旱发生频率都较高。3)近30年来干旱影响范围逐渐扩大,向区域性、全域性等大范围干旱扩展。从季节变化来看,春季和冬季干旱影响范围呈现出减小的趋势,夏季和秋季干旱影响范围则表现出扩大的趋势。

This study investigated spatial and temporal variations of droughts over Yunnan Province of China during1961—2012.On the basis of dataset from 126 meteorological stations covering the region,the standardized precipitation index derived from monthly precipitation was computed and analyzed.Our results indicated that the drought intensity increased in annual scale but different trends are observed in seasonal scale.The drought intensity showed an increasing trend in summer and autumn;however,it exhibited a decreasing trend in spring.The trend of drought intensity in winter was not obvious.A notable feature for drought intensity was that approximately 82% of the stations had increasing trend,and these stations mainly distributed in eastern Yunnan.The drought frequency in the northwestern,central,southeastern and southwestern regions was relatively high.The eastern and northeastern regions were prone to experience extremely drought.The spring drought mostly occurred in the northwestern and western regions,summer drought occurred in western and southwestern regions.The autumn drought mostly taken place in western,southwestern,central and northeastern regions.Most regions were experienced winter drought.The influence area of drought was significant increase in the past 30 years.At seasonal scale,the influence areas of drought present a decreasing trend in spring and winter,in contrast,an increasing trend were found in summer and autumn.