基于SPEI的河南省冬小麦生育期干旱时空特征分析

利用河南省24个地面气象站1961-2009年逐日降水和气温资料计算SPEI(标准化降水蒸散指数),并按照SPEI的标准界值将干旱强度划分为轻度干旱、中度干旱和极端干旱.根据河南省冬小麦的生长特点将小麦生育期划分为生育前期、分蘖期和返青-抽穗-成熟期.采用Meteoinfo软件、Morlet小波分析方法、线性回归研究不同生育期干旱变化趋势、覆盖范围、发生频率、周期及空间分布,结果表明,冬小麦各个生育阶段均出现过不同程度的干旱,只是不同地区、不同年份发生的频率和强度不同,但各阶段均存在着轻度干旱发生的概率最大,而极端干旱发生的概率最小的特点.驻马店地区在各阶段发生干旱的概率都较大.对河南省冬小麦全生育期的SPEI分析表明,全生育期干旱出现概率的极值中心有显著的10 a左右的周期变化特征,近年来干旱指数呈逐渐增大的趋势.

Temporal and spatial variation characteristics of drought trend at growth stage of winter wheat in Henan province based on SPEI index

Based on the precipitation,air temperature and evaporation data in Henan province during 1961-2009,the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated,hence the strength of drought during different growth stage of winter wheat in Henan province was graded by the SPEI and divided into slight,moderate and extreme droughts.According to the growth characteristics,the growth period of winter wheat in Henan province are divided into early growth period,tillering stage,and turning green-heading-maturity period.The drought characteristics including interdecadal trend,coverage area,frequency,period and spatial distribution were analyzed and compared using Meteoinfo software,Morlet wavelet analysis,and linear regression method.Results show that the characteristics of drought in different growing stages of winter wheat were different,and the drought''s frequency and intensity were various in different regions or years.But the slight drought takes up the maximum probability,while the extreme drought has the minimum probability,which is a common feature during all growth periods.The drought occurrence in Zhumadian City has the maximum probability in every growth period.The major periods of extreme point for drought during the whole growth period were about 10a.The SPEI increased in Henan in recent years,indicating a drought trend in future for Henan province.