Spatial and temporal characteristics of summer precipitation events spanning different numbers of days over Asia

Abstract

ABSTRACTConsidering the physical connections with circulation systems of different life cycles, precipitation events are classified based on their durations (the number of consecutive days with significant precipitation). By analysing spatial and temporal characteristics of summer precipitation events of different types over Asia, the present study indicates that weather systems with different life cycles predominate over different regions of Asia and control the occurrence of precipitation events of different types and their respective contributions to precipitation days and amount. Mid‐high latitude blockings govern the North Asian region and result in more long duration (over‐8‐day) events contributing a non‐negligible part to total number of precipitation days (NOPDs) and precipitation amount. Synoptic weather processes induce more short duration events and increase the fractional contribution of short duration events over the central Asian region. Persistent Asian monsoon‐related circulations and intermittent intrusions of cold air flows from the north produce long (over‐14‐day) and short (3‐to 5‐day) duration events, respectively, which contribute a high percentage over southern China. The Indian summer monsoon and the topographic effect jointly cause more over‐14‐day events and make a larger contribution over the west coast of the Indian Peninsula. The mean intensity of different events, as well as intense precipitation events, has obvious regional dependence and is affected by different weather systems and topographic effects. The interdecadal changes in total NOPDs and the regrouping of events with different durations and intensities are both responsible for the interdecadal increases in total precipitation amount over Northeast China and the upper reaches of the Yangtze River valley around the late 1970s and that over southern China around 1993.The interdecadal decrease in precipitation over southern China around the late 1970s is primarily attributed to the regrouping of different events rather than the changing NOPDs.