基于不同土壤类型的东部季风区骤旱时空演变特征

基于1979—2012年土壤湿度、地表平均温度、土壤蒸散量、土壤类型格点数据构建骤旱（flash drought, FD）指数，分析中国东部季风气候区骤旱的时空演变特征，揭示不同土壤类型对骤旱响应规律的空间异质性．研究结果表明:1）东部季风区骤旱次数与时间总体呈“南少北多”格局，气温变化是影响骤旱发生的主导性因素；东北部与中部发生的骤旱时间和频率最高．2）年际骤旱次数呈不显著上升趋势，区域内骤旱年平均发生总次数为40~50次，总时间为520~670 d，最大发生次数为56次，发生频率>0.04．从平均时间上看，淋溶土、初育土、人为土和铁铝土对骤旱的响应最为强烈．3）不同土壤类型骤旱年际变化分为2类，第1类分布在北部地区，在夏季达到高峰，春秋季几乎不发生；第2类分布在南部地区，在夏季达到高峰，且伴随着春秋季小高峰． 

Spatio-temporal evolution of flash droughts in eastern monsoon region according to different soil types

Global warming and frequent high-temperature heat wave events have resulted in flash droughts (droughts different from traditional agricultural and meteorological droughts), raising widespread attention in recent years．Data of soil moisture, average surface temperature, soil evapotranspiration, and soil type grids from 1979—2012 were used to construct a flash drought index to analyze temporal and spatial evolution of flash droughts in the Chinese eastern monsoon region, and to reveal spatial heterogeneity of different soil types in response to flash drought．Number and duration of flash droughts showed a pattern of "less in the south but more in the north"．Temperature changes were found to be the dominant factor affecting occurrence of flash droughts．Occurrence and frequency of flash droughts in northeastern part of the eastern monsoon region were relatively high．The occurrence time of interannual droughts did not increase significantly．The average total occurrence time of droughts in the region was 40?50, total duration was 520?670 days, maximum occurrence time was 56 days or more, frequency was 0.04 or more．At average duration, leached soil, primary soil, man-made soil and ferro-alumina were found to respond most strongly to flash drought．Variations of different types of soil droughts during the year were divided into two types: the first type in the northern region reached peak in summer but hardly occurred in spring and autumn; the second type in the southern region reached peak in summer but was accompanied by small peaks in spring and autumn．