改进的综合气象干旱指数CI_(new)及其适用性分析

An Improved Comprehensive Meteorological Drought Index CI_(new) and Its Applicability Analysis

针对综合气象干旱指数CI的"不合理旱情加剧"问题,采用线性递减权重方法计算近90d降水和可能蒸散,提出改进的综合气象干旱指数CInew,并从干旱过程描述能力、干旱频率及旱期相对少雨季节滞后特征方面,通过与CI相比较阐述CInew的适用性特征。结果表明,(1)CInew在无降水时段平稳下降,有效克服了CI的"不合理旱情加剧"问题,能够描述干旱发生、发展和结束过程的丰富细节;(2)CInew的干旱频率与CI相比没有统计意义上的差异,但由于新的相对湿润度指数项MI90new统计时段由原来的30d延长至90d,使CInew能够刻画干旱频发开始月份(11月)相对于少雨时段开始月份(10月)的滞后效应。本文可为CInew在国内其它地方推广应用提供参考。

Aiming at the ＂unreasonable drought aggravate＂ problem of the comprehensive meteorological drought index CI,using linear decreasing precipitation and potential evapotranspiration accumulating methods,an improved comprehensive meteorological drought index,CInew,was put forward in the paper.Comparing with CI,applicability characteristics of CInew was analyzed from the aspects of describing ability of drought course,draught frequency features and hysteresis effect.The results showed that：（1） CInew decreased steadily during no-precipitation period,therefore,CInew effectively avoided the ＂unreasonable drought aggravate＂ problem of CI,and was able to describe occurrence,development and end of drought process with rich details.（2） There was no statistical significant difference between drought frequency derived from CInew and that from CI,however,since statistical period of new relative moisture index MI90new extended to 90 days,CInew was enabled to show hysteresis of drought season beginning month（November） to less rain season beginning month（October）.The paper provides a reference when CInew is popularized to other places of China.