海河流域不同地形站网密度对面雨量精度的影响

Impact of station density on accuracy of area rainfall under different topography over Haihe River basin

利用2011—2013年汛期海河流域逐时降水量资料,将国家常规气象站与区域加密站进行分拣合成,通过面雨量离差系数和面雨量比值系数、点面关系综合分析不同地形条件下站网密度对海河流域各水系面雨量计算精度的影响。结果表明:站网密度是影响面雨量计算精度的重要因素,对不同地形面雨量分析存在不同程度的影响。其中,混合地貌水系以地形分布和降水分布差异尤为明显的滦河水系影响最大,站网密度较低的常规站对面雨量估计比高站网密度的合成站平均偏高2.5 mm,12%误差超过5.0 mm;其次山区永定河水系低站网密度常规站对面雨量估计平均偏高1.5 mm,相对误差达80.3%,尤其局地性短时强降水时,面雨量分析误差高达10倍以上;此外,混合地貌水系北三河和南运河站网密度对面雨量影响程度略低于滦河水系,平原区徒骇马颊河及混合地貌中地形差异较小的大清河和子牙河影响较小。

Based on hourly precipitation data from conventional weather stations and regional automatic stations o-ver Haihe River basin in flood season from 2011 to 2013 ,a set of new rainfall data with high network density was generated and this new data is from synthetic weather stations.Effects of station density under different topography on accuracy of area rainfall were analyzed by using area rainfall dispersion coefficient and its ratio coefficient as well as relationship between point rainfall and area rainfall.The results show that station density is an important factor which affects accuracy of area rainfall,and it has different effects on area rainfall under different topogra-phy.In water system of mixed topography such as Luanhe River basin,topography and precipitation are complex, so effect of station density is also the most significant.Area rainfall is overestimated about 2.5 mm using lower density data from conventional weather stations compared with using higher density data from synthetic weather stations,and 12%errors exceed 5.0 mm.In water system of mountain area topography such as Yongdinghe River, it is more than 1.5 mm,and relative errors reach 80.3%,especially during local short-time precipitation,errors of area rainfall is ten times as large as the true value.Additionally,station density has lower impact in mixed topogra-phy such as Beisanhe River,Nanyunhe River than in Luanhe River,so is in Tuhaimajiahe River of plain area,and the area with small difference of topography such as Daqinghe River and Ziyahe River.