Spatiotemporal variability of event-based rainstorm: The perspective of rainfall pattern and concentration

Rainfall pattern (RP) and precipitation concentration (PC) are two critical indices for measuring rainfall. Detecting their changes under global warming helps to understand better the rainfall variability and the flooding formation. Using the Guangdong Province, China, as a study case, five criteria were used to determine the independent precipitation events for hourly precipitation data from 1967 to 2012. The RP and PC of the events were identified, and then, their spatiotemporal variability was investigated further. The results show that (a) the occurrence frequency during 46 years, average rainfall amount and duration of independent rainfall in the coastal areas were higher than in other regions. (b) The dominant RPs in Guangdong are unimodal (more than 70%), especially the pattern with early peak (mode I; 39.5%); however, the number of stations with mode I as dominant RP decreased over time, while those with mode III (the pattern with late peak) increased. (c) Precipitation concentration index can be used for measuring the concentration of independent rainfall events, and its fixed minimum inter-event time has significant impacts on RP and PC. The PC of the events with early peak is higher, and the concentration in the west is generally higher than those in the east under different RPs.