Spatial-temporal distribution characteristics of extreme precipitation in the warm season in North China under the complex topography of the Taihang Mountains
In the context of global warming,frequent extreme precipitation events pose a serious threat to people's livelihoods,production,and the economic development of society.The topography of North China(NC)is complex and diverse,and the distribution of precipitation is inconsistent due to the influence of terrain.In parti-cular,there are significant geographical differences in the intensity and frequency of extreme precipitation.This study systematically analyzed the spatiotemporal distribution characteristics of precipitation amount,intensity,and frequency of extreme precipitation events in NC and its subregions.The analysis utilized daily precipitation data and station topographic height data from five provinces between May and September,spanning the period of 202 to 2021.By calculating the 95th percentile of daily precipitation at each station throughout the study area,regional extreme precipitation events in NC were filtered.Geographically Weighted Regression(GWR)models were used to investigate the relationship between precipitation,the intensity and frequency of extreme precipitation events,and altitude.The results indicate that extreme precipitation in NC has exhibited multiple fluctuations over time,with significant regional variations.The plateau to the west of the Taihang Mountains and the plains to the east of the Taihang Mountains experienced more frequent yet fluctuating and low-intensity precipitation,while the plains to the south had less frequent yet gradually changing and significantly stronger precipitation.The spatial distribu-tion of extreme precipitation indicates lower levels in the southern and northern regions and higher levels in the central region,influenced by factors such as topography.The extensive precipitation areas are located in the south-eastern part of the Yanshan Mountains and at the junction of Shanxi,Hebei,and Henan Provinces.The average an-nual precipitation of the above two regions exceeds 200 mm,and the precipitation of some stations exceeds 280 mm.During extreme precipitation events,heavy rainfall often occurs at each weather station,indicating a tendency for clustering.The stations with the highest frequency of heavy precipitation are mainly located in the southeastern part of Shanxi Province.Moreover,stations that recorded maximum daily precipitation of over 300 mm are mainly concentrated in the transition zone between the Taihang and Yanshan Mountains,as well as the NC Plain.The di-verse impact of regional topographies on precipitation intensity and frequency leads to significant variations in the characteristics of extreme precipitation,precipitation frequency,intensity,and daily maximum precipitation with altitude in the northern and southern parts of the NC area,which is divided by 38 °N.In the northern part of NC,the extreme precipitation,frequency,intensity,and daily maximum precipitation all decrease with the increase of altitude.There are significant regional differences in the variation of precipitation south of 38 °N with altitude,and the variables that dominate this difference vary from region to region.The significant increase in precipitation in the Linfen and Yuncheng areas of southern Shanxi with increasing altitude is due to the positive correlation be-tween precipitation frequency and intensity with terrain.The main factor contributing to the decrease in precipitati-on near the Taihang Mountains with increasing altitude is the intensity of precipitation,not its frequency.
North Chinaextreme precipitation events in the warm seasonspace time characteristicsgeographi-cally-weighted regression modeltopography