Analysis on Characteristics of Extreme Hourly Precipitation in Warm Season in the Haihe River Basin from 2010 to 2019
Based on the hourly precipitation data from 4517 meteorological stations(national basic weather station and regional automatic weather station)in Haihe River Basin and the ERA-5 reanalysis data,this paper statistically analyzes the threshold,frequency,spatio-temporal changes and weather pat-terns of extreme hourly precipitation(EHP)in the warm season in Haihe River Basin from 2010 to 2019 by means of the percentile method.The results show that:(1)The average value of 99.9％quantile of hourly rainfall intensity is 45.6 mm·h-1 and the 99.9％quantile of hourly rainfall intensity in 67％of the sites exceeds 45.0 mm·h-1.Therefore,the value 45.0 mm·h-1 is taken as the threshold of EHP in Haihe River Basin.(2)Spatial distribution of EHP frequency in Haihe River Basin is closely related to geographical location and topographical features.The EHP frequency in the plain areas is higher than in the mountain,and that in front of mountains is higher than that on mountains.Along the altitude,the EHP frequency increases first and then decreases,and its peak value tends to appear at the altitude of(450,500]m in Haihe River Basin.After that,there is a trend of decreasing volatility.(3)The inter-annual variation of the EHP frequency firstly increases and then decreases with the year of 2016 as the demarcation point.Two peaks of EHP intensity appear in 2012 and 2016,respectively.EHP is mainly concentrated in July and August every year,with an average intensity of more than 60 mm·h-1 and a fre-quency of 78.6％of the whole year.The diurnal variations of frequency and intensity show a double-peak pattern,and the peaks are observed in the afternoon and the early morning,especially after the noon time.(4)The statistical results of EHP frequency and intensity of different weather patterns indicate that the proportion of edge classes of subtropical high in EHP events from July to August is relatively large.The peak of EHP frequency in the afternoon is mainly caused by low vortex,shear and low trough,and EHP in the early morning is closely associated with the subtropical high edge class.The maximum inten-sity of median of EHP belongs to vortex shear type,while the minimum intensity of median of EHP is the trough type.
extreme hourly precipitationtopographyspatial and temporal distributionweather patternHaihe River Basin
NETL
NSTL
万方数据
