游程理论在云南省干旱重现期分析中的应用

运用游程分析理论计算干旱频率和重现期等数字特征，估计区域实际不同历时干旱重现期大小。选取云南省内26个气象站作为代表站，以多年逐月降水量距平百分率为指标，采用5组不同的截取水平识别干旱过程，分析了不同截取水平下干旱频率和重现期的统计规律，并选定截取水平为-0.4绘制了全省范围内干旱历时为4～9个月的干旱重现期分布图。结果表明，同一干旱历时的重现期随截取水平绝对值的增大而增大，同一截取水平下的重现期随历时单调递增；云南省干旱历时为1、2、3个月的干旱重现期分别小于5个月、2年和10年一遇，大于10个月的干旱重现期都大于150年一遇；云南省干旱易发区分布在丽江、大理、楚雄和昆明一带，西北部贡山一带为干旱少发区。

Application of Run length Theory to Drought Return Period Analysis of Yunnan Province

In order to estimate the actual value of return period of different drought duration on the study area, this paper calculated some digital characteristics of drought frequency and return period by using the run length analysis theory. By selecting 44 years percentage of precipitation anomalies of every month as an index, this paper used five different levels to identify drought processes and analyze the statistical law of drought frequency and return period of Yunnan Province, where 26 meteorological stations were chosen as representative stations. Also by specifying 0.4 as the value of cutting level, this paper drawn 4 9 months drought duration distribution maps of the whole province. The results show that the return period value of the same drought duration increases along with the increase of absolute value of the cutting level; the return period value of the same cutting level monotonically increases along with the increase of drought duration; the return period value in Yunnan of 1, 2, 3 months drought duration is respectively less than 5 months, 2 years,10 years; the return period value of drought duration, which is longer than 10 months, is greater than 150 years; the largest possibility of dry regions in Yunnan distributes in Lijiang, Dali, Chuxiong and Kunming areas; Gongshan area in Northwest Yunnan has the least possibility to turn into a dry region.