基于CI指数的湖北干旱及其变化特征分析

利用湖北省71个气象台站1960～2011年地面观测资料，按照国家标准《气象干旱等级GB/T20481 2006》中的综合气象干旱指数CI对湖北省干旱特点及其气候变化特征进行了分析。结果表明：(1)西北部地区全年有近1/3的时间为干旱日，季节变化差异小，是湖北省易干旱地区；中东部地区年干旱日天数相对较少，但集中在7～10月伏秋季，是湖北典型的季节性干旱地区；(2)湖北省中旱以上干旱过程平均1 a一次；重旱过程平均2~3 a一遇，其中西北部地区2 a一遇；而特重旱过程全省平均6～7 a一遇，其中西北部地区为5 a一遇；70%重旱过程出现在伏秋季;(3)全球气候变化背景下，湖北省一般性干旱年出现频率有明显的增加，而大旱年出现频率变化不大；空间上近20 a西北部地区的大旱年出现频率增加明显；中东部地区大旱年呈减少趋势，而一般性干旱年出现频率呈增加趋势；(4)中东部地区中旱过程出现频率近20 a增多较明显，主要反映在7～10月伏秋季，重旱过程呈减少趋势；而西北部地区重旱过程增加，主要表现在11～2月冬闲季和3～6月春夏季

CHARACTERISTICS AND VARIATIONS OF DROUGHT IN HUBEI BASED ON COMPREHENSIVE METEOROLOGICAL DROUGHT INDEX

Based on Comprehensive Meteorological Drought Index (CI),the metrorological data of 71 observation stations from 1960 to 2011 were used to analyze the characteristics of droughts in Hubei province.It was found that the droughts occurred nearly one third year in northwestern part with a slight seasonal difference,which was the drought prone area in Hubei.The droughts occurred in middle and eastern part relatively fewer,which was the typical area of seasonal drought with an intensive period from July to October.The moderate and above drought occurred every year,and severe drought occurred once per 25 years,in which severe drought occurred once per 2 years in northwestern part.Severest drought occurred once per 6-7 years in Hubei province,and 70% occurred during midsummer to autumn with a frequency of once per 5 years in northwestern part.Under the background of global climate change,the occurrence of universality drought in Hubei province increased slightly,but the severe drought changed a little.In the space distribution,the occurrence of severe drought increased in northwestern part but decreased in middle and eastern part in recent 20 years.And the universality drought in middle and eastern increased slightly.The moderate drought increased obviously in middle eastern part in recent 20 years,which occurred mainly during the period from July to October.But the occurrence of severe drought showed a decreasing trend and it increased in northwest part which occurred intensively from November to next February and March to June