Time distribution pattern and spatial heterogeneity of hourly scale event-based extreme precipitation in China

Extreme precipitation occurs naturally in the form of "events," and the spatio-temporal distribution pattern of event-based extreme precipitation is of great significance to flood disaster prevention and water resources protection. This study proposed the concept of hourly scale event-based extreme precipitation (HEEP), referring to a precipitation event with at least an hourly precipitation extreme (exceeding the 99th percentile threshold). Then we identified the dominant time distribution pattern (TDP), analyzed the seasonal proportion and distribution, and investigated the spatial distribution of three basic features (total frequency, amount, and duration) of HEEP from 2008 to 2017 in China and its nine major river basins. Results showed that over 90% of the areas in China were dominated by short-duration HEEP (S-HEEP, less than eight hours). While the rest areas were led by long-duration HEEP (L-HEEP, more than eight hours), mainly concentrated on the middle and lower reaches of the Yangtze River and southeast coastal areas of China. Areas dominated by S-HEEP were more than L-HEEP in different seasons except in winter. Three basic features of HEEP showed similar spatial distribution patterns of high in southeastern China and low in northwestern China, indicating HEEP frequently occurred in southeastern China with relatively large amounts and long duration. The concept of HEEP can provide new ideas for regional and global extreme precipitation research.