基于CI和强度分析方法的四川冬春季干旱事件变化特征

Variation characteristics of the winter and spring drought events in Sichuan based on CI and Intensity analysis

区域气象干旱动态变化过程和转换规律的研究对灾害预警与应对有重大意义。利用1985-2015年四川30个气象站点逐日20-20时降水量、平均气温资料,采用综合气象干旱指数(CI)与intensity analysis等方法,从干旱事件频次、干旱等级变化强度和干旱等级转换三个方面,分析了近30年四川冬春季干旱事件的变化特征,结果表明:1985年冬-2015年春四川冬春季干旱事件发生频率高、持续时间长、强度大;区域性干旱事件发生率高达77.78%,4月发生区域性干旱事件的频次最高;1985年冬-2015年春四川冬春季干旱等级变化强度表现出“快-慢-快”的变化特征;其中,2005年冬-2015年春较往年有变干趋势;1985年冬-2015年春四川冬春季干旱等级转换较活跃,各干旱等级的转换速率不尽相同,主要集中在轻旱、中旱、重旱三个等级,且有增加趋势。

Research on the dynamic change process and transformation law of regional meteorological drought is of great significance to disaster early warning and response.Based on daily precipitation,average temperature data of 30 meteorological stations in Sichuan from 1985 to 2015,using Comprehensive Meteorological Drought Index(CI)and intensity analysis method,this study analyzed the variation characteristics of drought events in winter and spring in Sichuan in recent 30 years from three aspects:frequency of drought events,variation intensity of drought grade and conversion of drought grade.The results show that:From the winter of 1985 to the spring of 2015,the winter and spring drought events in Sichuan had high frequency,long duration and high intensity.The incidence of regional drought events was as high as 77.78%,and the frequency of regional drought events was the highest in April.From the winter of 1985 to the spring of 2015,the change intensity of the drought grade in winter and spring of Sichuan showed the characteristics of“fast-slow-fast”change.Among them,from winter 2005 to spring 2015,there was a drying trend.From the winter of 1985 to the spring of 2015,the conversion rate of winter and spring drought grades in Sichuan was quite active,and the conversion rate of each drought grade was not the same,mainly concentrated in the three grades of light drought,moderate drought and severe drought,with an increasing trend.