中国降水测量误差的研究

20世纪 ,国际上许多国家对降水测量进行了对比试验工作 ,以研究降水测量中的误差大小与分布。由于各个国家降水测量仪器的型式、尺寸以及安装高度不同 ,试验对比的降水测量误差的大小也就不同。为了弄清中国降水测量误差的大小 ,中国气象局选择了 30个基准基本站 ,建立标准雨量站网进行试验对比。本文介绍了中国标准雨量站网的设置以及对比资料的获取情况 ,对比分析了中国降水测量的随机误差、沾湿与蒸发误差、风场变形误差。经 30个标准雨量站 7a 2 90 0 0多次的 1台坑式雨量器、2台台站雨量器的对比观测 ,给出了中国降水量测量误差的大小、降水测量中的随机误差与系统误差的分布情况。经分析 ,对于收集口口径为 2 0cm ,安装高度为 70cm的台站普通雨量器 ,每次测量随机误差累计平均值为 0 .0mm ,沾湿误差为 0 .2mm ,蒸发误差为 0 .0mm ,降雨风场变形误差为 0 .19mm ,降雪为 0 .32mm。降雨测量的平均相对误差约为 4 .34%～ 15 .2 8% ,降雪测量的平均相对误差约为 6 .17%～ 39.99%。

THE RESEARCH OF PRECIPITATION MEASUREMENT ERRORS IN CHINA

In order to understand precipitation measurement errors clearly, comparative tests about precipitation were carried out in many countries in the 20th century. Because the raingauges to measure precipitation amount are varied in type, dimensions and installation height in different countries, the size of precipitation measurement error is not the same among various countries. To understand precipitation measurement errors in China, 30 standard rainfall stations for precipitation comparative observation were set up all over the country before 1993. The stations are all of reference or principal climatological stations in China. The installation of standard rainfall stations and the collection about comparative data from those stations are introduced. The random error, the wetted error, the evaporation error and the wind induced error in precipitation measurements are studied. Comparative observations have been conducted between pit gauge, 2 operational gauges for seven years at 30 stations about 29000 events, the sizes of the above these errors are given. The distribution of random errors and systematic errors in precipitation measurements are studied. For the operational gauge whose diameter of receiving orifice is 20 cm and installing height is 70 cm,the wetted error is 0.2 cm and the evaporation error is 0.0 mm for each event ,the random error is 0.0 mm for even measurement and the wind induced average error is 0.19 mm and 0.32 mm respectively for rain and snow measurement. The relative error in rain measurements varies from 4.34% to 15.28%, 6.17% to 39.99% in snow observations.