Extreme Meteorological Drought Events over China (1951–2022): Migration Patterns, Diversity of Temperature Extremes, and Decadal Variations

Abstract

Recently, extreme meteorological droughts have affected China, causing terrible socioeconomic impacts. Despite previous research on the spatiotemporal characteristics and mechanisms of drought, two crucial issues remain seldom explored. First, an event-oriented drought chronology with detailed spatiotemporal evolutions is urgently required. Second, the complex migration patterns and diversity of synchronous temperature extremes need to be quantitatively investigated. Accordingly, the main achievements of our investigation are as follows. We produced an event-oriented set of extreme meteorological droughts over China through the application of a newly developed 3D DBSCAN-based detection method (deposited on https://doi.org/10.25452/figshare.plus.25512334), which was verified with a historical atlas and monographs on a case-by-case basis. In addition, distinctive migration patterns (i.e., stationary/propagation types) are identified and ranked, considering the differences in latitudinal zones and coastal/inland locations. We also analyze the diversity of synchronous temperature extremes (e.g., hotness and coldness). Notably, an increasing trend in hot droughts occurred over China since the late 1990s, predominantly appearing to the south of 30°N and north of 40°N. All drought events and synchronous temperature extremes are ranked using a comprehensive magnitude index, with the 2022 summer-autumn Yangtze River hot drought being the hottest. Furthermore, Liang-Kleeman information flow-based causality analysis emphasizes key areas where the PDO and AMO influenced decadal variations in coverages of droughts and temperature extremes. We believe that the achievements in this study may offer new insights into sequential mechanism exploration and prediction-related issues.