How is about the flash drought events and their impacts on vegetation in Central Asia

A flash drought typically exhibits rapid development and high intensity, with significant impacts on societies and ecosystems. Central Asia (CA), a typical arid region, little attention has been paid to the characteristics of flash droughts and their impact on ecosystems. Therefore, a novel composite decomposition flash drought identification (CDFDI) framework was adopted to integrate data on soil moisture, normalized difference vegetation index (NDVI), and gross primary productivity to identify flash drought as a subphase of regular drought in CA. This study aims to explore flash drought characteristics and vegetation response in CA, comparing them with existing identification methods to assess the effectiveness of the flash drought identification framework. The main findings are: (1) introducing inter-event time and volume criterion and Madsen methods in the CDFDI framework yielded promising results, verified through correlation between flash drought characteristics and NDVI deficits (e.g., the average percentage of correlations between flash drought features and NDVI in the - 1 to -0.5 and 0.5 to 1 intervals was 15%); (2) the northern, central, eastern, and southeastern CA were frequently affected by flash droughts, while the western region experienced prolonged regular droughts with an insignificant weakening trend between 1948 and 2022; and (3) Average gross primary productivity response time was 30 days, and its spatial distribution indicated that the impacts of flash drought on vegetation were more immediate in the comparatively arid western CA. This study provides new insights into identifying and characterizing flash drought in changing environments, contributing to a better understanding of its impacts on ecosystems.