星载雷达与地基雷达数据的个例对比分析

Comparative Case Study on the Observations between the Space-borne Radar and Ground-based Radar

采用几何匹配法将TRMM(Tropical Rainfall Measuring Mission)卫星搭载的测雨雷达(Precipitation Radar,PR)和上海地基雷达(Ground-based Radar,GR)有效照射体积的观测数据进行时空匹配,得到了2007年下半年3个时次上海地区的降水个例。考虑到PR与GR工作频率的不同,本文将S波段GR探测到的回波强度值调整为Ku波段PR探测到的回波强度值(称为Ku调整),进而比较PR和GR测量的反射率因子数值差异,并分析了不同降水类型和不同高度层的PR-GR偏差。结果表明:(1)PR和GR探测到的降水回波分布型大体一致,但PR探测到的降水回波强度普遍比GR探测到的大;(2)在零度层亮带以内及以下的PR与GR反射率因子资料具有较好的相关性;(3)由于GR的波束充塞效应及回波衰减,高层PR-GR平均偏差比低层大;(4)GR和PR的回波强度变化特征一致性在层云降水情况下优于对流降水情况;(5)整体而言,Ku调整使GR和PR数据更接近。

This paper obtained three cases of precipitation in Shanghai in the second half year of 2007 after applying the Geometry- matching method to do the Temporal- Spatial M atching of radar data derived from the precipitation radar( PR) on the TRM M( Tropical Rainfall Measuring Mission satellite) and from Shanghai Ground- based Radar( GR) in their effective sampling volume. To compare the difference between the volume- matched PR and GR radar reflectivity factor in consideration of the different frequencies of PR and GR,we adjust the echo intensity detected by Ground- based Radar( GR) which is in S- band to that value which is detected by Ku- band Radar( Ku- adjusted),and analyze the PR- GR deviation from different altitude layers and various precipitation types. The results showthat:(1) The distribution and structure of PR are in accordance with GR echoes as a whole,whereas the PR echoes are more intense than the GR echoes generally.(2) Within and belowthe Bright- band,there is a high degree of correlation between PR and GR reflectivity data.(3) Due to the impact of beam filling and the attenuation of echoes,the mean deviation of PR-GR is larger in high altitude layer than in lowaltitude layer.(4) The variation characteristic of PR and GR echoes intensity has a higher degree of consistency from stratiform precipitation samples than convective precipitation samples.(5) In general,the GR data is closer to PR data after the Ku-adjusted.