Intensifying Hydrometeorological Extreme Events and Compound Anomalies in a Temperate Region, Germany

Hydrometeorological extremes (HMEs) pose immense challenges and hazards to communities in a warming world, and this is particularly true for compound extremes (CHMEs) associated with deadly wet and dry events. More attention has been paid to extremes happening in arid and wet regions, nonetheless, temperate regions are understood poorly where more and more HMEs are striking fragile social-ecological systems. Therefore, the study shines a light on a proper temperate region of Europe, Germany. Not only the spatial-temporary variation of individual HMEs (IHMEs) but also compound events are fully investigated over the past seven decades. Notably, we propose a new insight to explore the concurrent extreme wet and dry events (CEDWs). A comprehensive framework is devised here, it combines the percentile and standardized index methods to explore compound extremes first. Different time scales are utilized to identify extreme wet (EWs) and dry events (EDs) separately considering their different evolving processes and impacting patterns on human society. The research presents the spatiotemporal distribution of the number, magnitude, and intensity of IHMEs and CHMEs in the wet and dry regions of Germany. Moreover, the changing tendency and spatial clustering of these events are further discussed by Ordinary Least Squares and Moran Index methods. Our study provides an important perspective on the changes in the spatiotemporal distribution of HMEs in the temperate region, especially the novel discussion of compound events. On the other hand, the research results regarding phases and areas of severe extremes facilitate planners and decision-makers to prioritize disaster management with limited resources and produce effective risk-mitigation plans.