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．