华西地区秋季小时降水变化特征分析OA北大核心CSTPCD

Under the background of climate change,there have been increasing trends in both the amount and intensity of autumn rainfall in West China in recent years.To comprehensively understand the long-term variations and daily characteristics of hourly precipitation,hourly precipitation data from 342 stations in West China from 1981 to 2023 were analyzed.The spatial distribution and temporal changes of hourly average precipitation,frequency,intensity,and extreme precipitation were investigated.The results are as follows.Overall,there is a slight increasing trend in hourly average precipitation in West China from 1981 to 2023.The frequency of precipitation events show a slight decreasing trend in the entire region as well as in the northern and southern regions.However,intensity exhibits a slight increase in the entire region and southern region,with a marginal decrease in the northern region.Diurnal variations consistently show a unimodal pattern,but the peak times differ between the southern(04꞉00-07꞉00)and northern(around 08꞉00,with low values from 16꞉00 to 20꞉00)regions.Spatially,hourly average precipitation exhibits a morning-dominant and afternoon-decreasing pattern,with rainfall moving from southwest to northeast and being more pronounced at night.However,there are significant spatial differences in intensity,with stronger nighttime precipitation in the southern region,whereas daytime precipitation is stronger in the northern region.The southeastern part of Gansu and southern part of Ningxia show relatively lower intensity with less pronounced diurnal variations.Extreme precipitation frequency shows an overall increasing trend,more significantly in the northern region.Diurnal variations in both the southern and northern regions exhibit a unimodal pattern,with nighttime peaks in the south and early morning peaks in the north.The contribution rate of extreme precipitation shows an overall increasing trend but a slight decreasing trend in the northern region.September exhibits the highest frequency and contribution rate of extreme precipitation,though the centers of maximum values do not coincide,the frequency peak is mainly in the junction area of Shaanxi,Sichuan,and Chongqing,while the contribution rate peak is in the western Sichuan basin.