Analysis of characteristics of the extreme short-time heavy rainfall in Guangxi in rain season

Abstract

Based on the hourly precipitation data from 2005 to 2021 at the 91 meteorological stations and Oceanic Niño Index in Guangxi in rain season, the spatial and temporal distribution characteristics of extreme short-time heavy rainfall are analyzed. The results show that: (1) In most parts of Guangxi, the intensity of extreme short-time heavy rainfall ranges from 40 to 70 mm·h-1. The highest intensity and frequency of extreme heavy rain are seen in the coastal areas, while the lowest intensity is seen in northern inland regions with more frequent heavy rain. (2) The number of extreme short-time heavy rainfall per year continues to rise. In May and June, the frequency of these events is the highest and the little monthly change of the heavy rainfall intensity has been observed. (3) The diurnal variation curve of the incidence of extreme heavy precipitation appears to be bimodal with peaks during 04∶00 BT-05∶00 BT and 05∶00 BT-06∶00 BT. The intensity of this kind of rainfall varies from 50 to 55 mm per hour with little variation in amplitude in different hours. (4) The spatial distribution characteristics of extreme short-time heavy rainfall is not only closely related to the terrain features, but also associated with the South China Sea summer monsoon onset and El Niño/La Nina event. (5) It is shown that there is a positive correlation between the Oceanic Niño Index of previous autumn and the frequency of extreme short-time heavy rainfall.

Keywords

• hourly extreme rainfall
• south china sea summer monsoon
• el niño
• la nia