雷达定量降水估计技术及效果评估

RADAR QUANTITATIVE PRECIPITATION ESTIMATION TECHNIQUES AND EFFECT EVALUATION

为提高雷达定量估测降水的精度,利用广东省6部新一代多普勒天气雷达(CINRAD/SA)回波资料和雨量计降水量观测资料,采用概率配对法(PFT,Probability-fitting technique)建立Z-I关系进行单部雷达降水估测,并采用最优插值法(OI,Optimum Interpolation)对降水估计进行订正;为扩大降水估测的范围,对多部雷达的降水估计进行拼接,采取重叠区域以各部雷达的均方根误差平方的倒数作为权重系数(iω==1/RMSE(K)2/n∑i-1/RMSE(i)2)进行加权平均,并分别分析比较上述方法得到的降水估计与单纯OI雨量计及与雷达拼图回波强度得到的降水估计的优劣。以上各环节误差分析表明,对于单部雷达,雨量计降水强度与其上空9点平均的雷达回波强度关系最为密切;6部相同型号的雷达估测降水精度各异。交叉检验表明,OI雷达法对单部和多部雷达估测降水均可取得较好的校准效果;对于多部雷达的降水估测,单部雷达先分别进行OI订正后拼接,然后对重叠区再次OI订正的结果比直接对未订正的单部雷达降水估计拼接后统一做一次OI订正的效果好。多部雷达降水估计拼接时,前期对于单部雷达降水估计的订正尤为重要;多部雷达降水估计的拼接值精度要明显高于OI雨量计,而相比由雷达拼图回波强度得到的降水估计而言,前者也优于后者。因此,多部雷达降水估计的拼接方法,对雷达资料的应用有较好的参考价值,在业务上也有一定的应用前景。

This research work is aimed at improving the radar QPE （Quantitative Precipitation Estimation） techniques. Based on CINRAD/SA dataset of volume scan reflectivity and rain gauge data in the Guangdong area, the probability-fitting technique （PFT）, which is adopted to localize the relationship between Z and/, and the OI （Optimum Interpolation） method, which is used to correct the radar precipitation estimation, have been used. In order to estimate large scale precipitation, multi-radar QPE was combined by weighting each radar by square multiplicative inverse（ω=1/RMSE（k）^2/^n∑i=1 1/RMSE（i）^2）of its RMSE （root mean square error）. Error statistical analyses indicated that station gauge rain is reflectivity above. Additionally, it was verified that the same model is different; As for the multi-radar QPE, most closely related to the average of nine point＇s QPE precision of each single-Doppler radar with the the result of 0I combination of corrected value of single-radar precipitation estimation is better than that of OI combination of single-radar precipitation estimation. Trough cross-validation, some conclusions were obtained that the OI correction method can minimize the precipitation estimation errors to a certain extent and correcting single radar precipitation estimation in advance is important. It was also shown that the method of multi-radar QPE combination is better than gauge＇s OI. Against the radar composite image hybrid reflectivity QPE, the precision of the former is higher than the latter. So, multi-radar QPE combination techniques have some reference value for application of radar data and have application prospective in operational weather services.