Flash drought pattern and trend in China during 1980-2022
In the context of global climate change, flash droughts occur frequently and can have a huge impact on agricultural production and ecosystem functions in the short term. Therefore, it is of great significance to comprehensively and accurately describe the characteristics and trends of drought for drought risk assessment and agricultural disaster reduction in China. This study used long-term land surface model data and reanalysis datasets to analyze the frequency, intensity, duration, and spatiotemporal distribution of flash drought events in China from 1980 to 2022. Two flash drought detection methods, based on evapotranspiration stress ratio and soil moisture were adopted, respectively, and the Mann-Kendall trend analysis method was used to evaluate the development trend of flash drought characteristics in different regions. The results show that: (1) The identified flash drought ranges using the two methods are more consistent in southeast China, yet great differences exist in northwest China. (2) The area with the highest occurrence of flash droughts identified by the evapotranspiration-based method is the Qinghai-Tibet Plateau, while that from the soil moisture-based method is the central region of Sichuan Province. (3) Flash drought occurrences distribute unevenly among seasons, which is the highest in summer, followed by spring and autumn, and the lowest in winter. (4) The average flash drought duration is mostly 6~10 pentads, it is longer in Northwest China identified by the evapotranspiration method, while it is longer in parts of northwestern and central China by the soil moisture method. (5) The areas with high-intensity flash droughts are Northeast China, Northwest China, Tibet Autonomous Region, and Taiwan Province identified by the evapotranspiration method, while it is in the Southern region by the soil moisture method. The two methods conduct distinct results, the suitability for different situations is waiting for further investigations.