星载雷达在订正地基天气雷达标定误差中的应用

在雷达反射率数据定量应用中,标定误差是导致结果产生偏差的重要原因之一。星载雷达（TRMM PR）长期工作的稳定性和连续性已被验证,本文将星载雷达数据转换到S波段,通过对比星载雷达和南京雷达同时段不同高度（相对于融化层的位置）不同降水类型（层云降水或对流降水）的数据,得到两部雷达对融化层以下层云降水的观测相关性高,差异稳定。通过对比分析星载雷达和南京雷达同时段零度层以下层状云降水的观测数据,得出两部雷达反射率因子值的回归关系式。以星载雷达观测数据为基准,使用该关系式对南京雷达反射率数据进行订正,并通过雨量计数据对订正结果进行验证,结果显示使用本文订正关系式订正后雷达估计的降雨量更接近雨量计的观测值。

Using Space-Borne Radar Data to Correcting Calibration Errors in Ground-Based Radar

A Calibration error is among the main causes of errors in the quantitative application of radar reflectivity. In this study, the stable and continue doperation of along-term space-borne radar (Precipitation Radar carried by the Tropical Rainfall Measuring Mission satellite, TRMM/PR) was verified. Reflectivity data from the space-borne radar were converted from Ku-band to S-band. By comparing the reflectivity data gathered from the space-borne radar and Nanjing radarover the same period for different types of precipitation (stratiform or convective) at different altitudes (relative to the position of melting layer, ML), it was determined that there was a high correlation between the two radars'' observations and a stable difference in stratiform precipitation below the ML. Further, the regression relationship between reflectivity factor values observed by the PR and Nanjing radar was obtained by comparing and analyzing the reflectivity factors of stratiform precipitation under the ML. Consequently, the regression between the two radar reflectivity factors provided a linear correction which was then applied to the reflectivity of the Nanjing radar. Rain gage data employed to verify this correction revealed that the precipitation estimated using GR reflectivity data with correction was closer to the rain gage observations than without.