Fine-scale analysis of hourly precipitation of West China autumn precipitation

The West China autumn precipitation (WCAP) is one of the most important climatic features in western regions of China (e.g. Shanxi, Sichuan, Chongqing, Guizhou), which is mainly characterized as continuous rain. Using the GPM precipitation data from 2011 to 2020, this study statistically analyzes the hourly characteristics of WCAP, including intensity-frequency distribution, duration, and diurnal variation. It is found that there are three key regions of WCAP: the central-eastern Sichuan Basin, the east of Yunnan-Guizhou Plateau, and the eastern periphery of the Tibetan Plateau. Further analysis of the detailed characteristics and differences of hourly precipitation between the three regions are as follows. (1) As regards the precipitation intensity-frequency distribution, both high precipitation frequency and strong precipitation intensity are found in the central-eastern Sichuan Basin, while a low precipitation frequency but strong precipitation in⁃ tensity in the east of Yunnan-Guizhou Plateau, with a high precipitation frequency but weak precipitation intensity in the east periphery of the Tibetan Plateau. (2) The diurnal peak phase of WCAP presents two spatial evolution patterns. The first one is located in the northern re⁃ gions, which shifts from the eastern periphery of the Tibetan Plateau peaking at 22∶00 BT to the central-eastern Sichuan Basin peaking at 06∶00 BT the next morning, showing a peak phase delay from west to east between these two regions. The second one is located in the east of the Yunnan-Guizhou Plateau, with the diurnal peak shifting from 18∶00 BT in the western part of this region to 16∶00 BT the next day in the eastern part. (3) From the perspective of the diurnal variation characteristics of precipitation events, with the increase in precipitation duration, the diurnal peak phase of precipitation in the eastern periphery of the Tibet Plateau shows a gradual delay signature. Two types of pre⁃ cipitation appear in both the central-eastern Sichuan Basin and the east of the Yunnan-Guizhou Plateau: afternoon short-duration precipita⁃ tion and morning long-duration precipitation. However, the morning long-duration precipitation in the central-eastern Sichuan Basin con⁃ tribute more to the total precipitation than that in the east of the Yunnan-Guizhou Plateau.