Temporal and spatial variation characteristics of extreme precipitation on the Loess Plateau of China facing the precipitation process

The preceding and succeeding precipitation (PSP) often act together with extreme precipitation (EP), in turn, causing floods, which is an objective component that is often overlooked with regard to summer flood hazards in the arid region of Northwest China. In this study, event-based extreme precipitation (EEP) was defined as continuous precipitation that includes at least one day of EP. We analyzed the spatiotemporal variation characteristics of four EEP types (front EEP, late EEP, balanced EEP, and single day EEP) across the Loess Plateau (LP) based on data acquired from 87 meteorological stations from 1960 to 2019. Precipitation on the LP basically maintained a spatial pattern of "low in the northwest region and high in the southeast region", and EP over the last 10 a increased significantly. The cumulative precipitation percentage of single day EEP was 34% and was dominant for 60 a, while the cumulative precipitation percentage of front, late, and balanced EEP types associated with PSP accounted for 66%, which confirms to the connotation of EEP. The cumulative frequencies of front and late EEP types were 23% and 21%, respectively, while the cumulative frequency of balanced EEP had the lowest value at only 13%. Moreover, global warming could lead to more single day EEP across the LP, and continuous EEP could increase in the northwestern region and decrease in the eastern region in the future. The concept of process-oriented EP could facilitate further exploration of disaster-causing processes associated with different types of EP, and provide a theoretical basis for deriving precipitation disaster chains and construction of disaster cluster characteristics.