乌兰布和沙漠东北部干旱指数的变化特征

Change of Drought Index in Dengkou County in Northeast of Wulanbuhe Desert

利用磴口县1954—2005年的降水、蒸发资料,分析该地区四季干旱指数的变化特征。研究表明,该地区气候以干旱为主,且持续时间长,最长达14 a之久。冬季与春季以重旱为主,重旱频率分别为40.4%与36.5%;夏季以中旱为主,中旱频率为38.5%;秋季重旱与中旱频率一致,为32.7%。这种气候特点与该地区降水主要集中在夏季有关。以年代际划分,70年代春季干旱最为严重,80年代夏季干旱最为严重,60、90年代秋季干旱最为严重,60、80及90年代冬季干旱最为严重。

Based on the precipitation and evaporation data of Dengkou county meteorological station from 1954 to 2005, the variety characteristic of drought index of four seasons are analyzed. The result shows that Dengkou＇s climatic is mainly drought ,lasting long time and the longest one is 14 years. Heavy drought is dominant in winter and spring ,the frequency of heavy drought is 40.4% and 36.5% respectively; it is mostly that moderate drought oecurrs in summer, the frequency of moderate drought is 38.5% ; the frequency of heavy drought is 32.7% as same as moderate drought in autumn. The cause is precipitation mainly concentrating in summer. Classifing by decade,drought is the most serious in spring of the 1970b, summer of the 1980＇s,autumn of the 1960＇s,the 1990b,winter of the 1960＇s,the 1980＇s and the 1990＇s.