三种不同干旱动态监测指数在陕西省的适用性研究

Application of three dynamic drought-monitoring indexes in Shaanxi Province

运用陕西省96个站1981—2012年近32年的逐日气温、降水、风速、相对湿度等资料,分别计算出各站逐日(向前滚动30天)的三种干旱动态监测指数:降水距平百分率(Pa)、相对湿润干旱指数(MI)、标准化降水指数(SPI),并将陕西省按地域由北至南分为陕北、关中、陕南,按季节分为春(3—5月)、夏(6—8月)、秋(9—11月)、冬(12—2月),分别统计出不同干旱动态监测指数对应的干旱发生的频率并与历史记载中实际干旱情况进行比对,对三种干旱动态监测指数在陕西省的适用性进行分析。结果表明:夏季MI指数得到的干旱频率最高,Pa指数最低,冬季MI指数得到的干旱频率最低,Pa指数最高;在春、冬季节Pa指数的适用性较好,在夏、秋季节MI指数的适用性较好;陕西省夏季容易发生局地强降水,而在秋、冬季容易出现长时间的无降水,导致SPI指数在夏、秋、冬季节的适用性不太好。

Based on the meteorological data such as daily temperature,precipitation,wind speed and relative humidity from 1981 to 2012 at 96 meteorological stations in Shaanxi Province,three daily dynamic drought-monitoring indexes,including percentage of precipitation anomalies（ Pa）,standardized precipitation index（ SPI） and relative moisture index（ MI）,were calculated for each station. By dividing the whole province geographically into north,central and south Shaanxi,and dividing the seasons into spring（ March to May）,summer（ June to August）,autumn（ September to November） and winter（ December to January）,the corresponding drought occurrence frequency of different drought-monitoring indices was calculated and compared with the historical record of actual drought events,so as to analyze the applicability of these drought-monitoring indexes in Shaanxi Province. The result showed that：（ 1） in summer,the drought occurrence frequency obtained by MI was the highest while that obtained by Pawas the lowest,but in winter,the drought occurrence frequency obtained by MI was the lowest while that obtained by Pawas the highest;（ 2） Pawas relatively suitable for spring and winter while MI was relatively suitable for summer and autumn;（ 3） since Shaanxi was prone to strong precipitation in summer but long-term lack of precipitation in autumn and winter,SPI was not suitable for summer,autumn and winter in Shaanxi Province.