4种干旱判别指数在东北地区适用性分析

利用东北地区207个国家基本气象站1961—2014年气象数据，计算改进后的综合气象干旱指数（MCI）、相对湿润度指数（MI）、标准化降水指数（SPI）以及标准化权重降水指数（SPIW）这4种常见的干旱指数，对比分析其在该区域的适用性，结果表明：在东北地区，4种气象干旱指数判断历年干旱持续天数及干旱过程强度的演变趋势基本一致；在干旱影响范围方面，SPI和SPIW指数对较长时间的干旱过程判别效果不佳，MCI指数能够较好的反应各时间尺度干旱过程的影响范围。在空间分布方面，SPI和SPIW指数无明显经向分布特征，MCI和MI指数的空间分布特征基本一致，呈现经向分布特征，干旱过程强度及干旱过程持续天数自西向东递减。从不同时间尺度的干旱影响范围、干旱累计强度和干旱持续天数的空间分布以及指数计算方法角度考虑，MCI指数较为接近实际灾情。

Applicability analysis of four drought indexes in northeast China

Northeast China is not only a significant cultural and economic region but also an important agricultural production area in China.With the continuous climate changes of recent years,the frequency and scope of droughts in northeast China have been increasing.It is important to better monitor and provide warnings of drought development in northeast China and to provide a basis for drought risk assessments in this region.This study used the daily meteorological data from 207 weather stations in northeast China,including data from three northeastern provinces and eastern Inner Mongolia,from 1961 to 2014 for the drought risk assessment.According to the National Classification for meteorological drought standards,the applicability of four drought indices,namely MCI,MI,SPI, and SPIW,in northeast China was evaluated.The results showed that the temporal evolution of the number of drought days and the intensity of drought processes obtained by four meteorological drought indices are generally consistent in northeast China.SPI and SPIW show poor performance for drought affected areas for longer drought processes.Compared with those two indices,MCI can reflect the range of drought impacts for various time periods.In their spatial distributions,SPI and SPIW show no clear spatial meridional variations.MCI and MI are spatially consistent in that they show meridional distribution and decline from west to east.From the drought affected areas at different time scales,the spatial distribution of the drought intensities,drought duration,and the various index calculation methods,MCI most closely represents the actual drought disasters.