偏振多普勒雷达定量测量降雨精度的改进  

An Improvement of Polarimetric Radar Rainfall Estimates

作　　者：赵果[1] 楚荣忠[1] 张彤[1] 贾伟[1] 沈瑾[1] 吴忠元[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所寒旱区陆面过程与气候变化重点实验室,甘肃兰州730000

出　　处：《高原气象》2011年第2期498-507,共10页Plateau Meteorology

基　　金：中国科学院西部行动计划(二期)项目(KZCX2-XB2-09);国家自然科学基金面上项目(40575008)共同资助

摘　　要：提高雷达估测降雨的精度一直都具有非常重要的实用意义,但是由于雨滴谱的地域差异性使得雷达测雨公式并不具有广泛的适用性。利用黑河流域遥感-地面观测同步试验(WATER项目)期间获得的大量不同类型降雨的雨滴谱资料,通过提取大量的雨滴直径D和对应的下落速度v,分析得到了它们之间的关系:v(D)=4.67D0.53。同时还得到了对应层状云和对流云雷达定量测量降雨的Z-R关系。利用滴谱数据计算得到对应X波段的双偏振雷达参数:差分反射率ZDR和差分传播相移常数KDP。并运用ZDR和KDP分别得到了适应层状云和对流云降雨的R(Z)、R(KDP)、R(Z,ZDR)和R(KDP,Z,ZDR)关系。通过降水过程获得的地面雨量筒数据和雷达实测数据,对各测雨方法进行了检验,发现组合参数的测雨公式能够很好地提高雷达测雨的精度。The quantitative estimation of rain rates using the meteorological radar has been one of main themes in radar meteorology and radar hydrology.The conventional single-polarized Doppler radar uses the measurement of radar reflectivity,radial velocity,and storm structure to infer some aspects of hydrometeor types and amounts.The relationships between rain rate R and the radar reflectivity factor Z（Z-R relations） have been widely used to estimate rainfall amounts.However,the classic rain estimation method has many sources of error.The sensitivity of Z-R relations to variations in raindrop size distribution（DSD） is the major source of error.Raindrop size distribution is determined by microphysical processes such as coalescence and breakup,condensation,evaporation,and melting of snowflakes,etc.DSD also changes in time and space,in correspondence with changes in microphysical process in a given precipitation system.Under the Watershed Airborne Telemetry Experimental Research（WATER） a lot of raindrop size distribution data were collected from May to July,2008.The experiment area（38.85°N,100.41°E） was carried out in the northeast of Qinghai-Xizhang Plateau,and the altitude is 1 515 m.The relationship between the terminal velocity of rain drop and rain drop diameter was obtained： v（D）=4.67D0.53.Four types of estimators for X-band polarimetric radar are examined： A classical estimator R（Z）,and three types of polarimetric radar estimator R（KDP） R（Z,ZDR） and R（KDP,Z,ZDR）,where R is the rain rate,Z is the reflectivity factor,KDP is the specific differential phase,and ZDR is the differential reflectivity.According to the simulated results,the normalized errors of R（Z）,R（KDP）,R（Z,ZDR） and R（KDP,Z,ZDR）,for stratiform rain and convective rain are 32.0%,18.2%,15.0%,12.3 % and 28.0%,16.8%,14.2%,11.3%,respectively.The percentage root-mean-squared error of R（Z）,R（KDP）,R（Z,ZDR） and R（KDP,Z,ZDR）,for stratiform rain and convective rain are 33.2%,19.1%,15.1%,13.3 %

关 键 词：雨滴谱 偏振多普勒雷达 差分反射率 差分传播相移常数 

分 类 号：TN959.4[电子电信—信号与信息处理]