Spatial and Temporal Variability of Rainstorms over China under Changed Climate

Rainstorms, as an extreme precipitation event, are a major driven for many disasters, such as urban waterlogging and mountain torrents. In the context of climate change, rainstorm events in China are occurring more and more frequently and widely in recent years, which induces numerous disasters and causes a huge loss of both life and wealth. Understanding the spatial and temporal pattern of rainstorms is thus critical for emergency response and scientific management of these disasters. Satellite missions such as Tropical Rainfall Measurement Mission (TRMM) and Global Precipitation Mission (GPM) have been collecting a large volume of precipitation data in recent years. These data provide large scale and long-term continuous precipitation information which is useful for continental precipitation studies. This study proposes an efficient tool of identifying rainstorms automatically from grid based precipitation dataset. Using this tool, rainstorm events in recent 20 years in China were extracted from time series of TRMM 3B42-V7 product, which has a spatial resolution of 0.25 arc degree and a temporal resolution of 3 hours. The seasonal and interannual variation of rainstorms, together with their occurrences, seasonality are mapped and analyzed. The longitude and latitude of annual rainstorm centroids were found to be both increasing slightly, indicating a northeast moving trend of the spatial distribution in the last 20 years. Intensity of the biggest rainstorms in different regions are compared and analyzed. It was found that areas having at least one rainstorm event in China exhibit an increasing trend in these years. Correlations between rainstorm occurrence and total precipitation, temperature, climatic oscillations (such as ENSO) are investigated to reveal the potential driving factors of rainstorms in China. It is hoped that this study could give a detailed picture about the spatial and temporal variability as well as its driving force of rainstorms in China, so that it can serve the purpose of supporting flooding management and other related studies.