海洋二号卫星微波散射计自然扩展目标在轨定标

海洋二号卫星微波散射计(HY-2 Scatterometer, HY-2 SCAT)是一种旋转扫描笔形波束散射计, 能够对同一观测面元提供4次方位角和入射角的观测组合, 并通过地球物理模型反演海面风场. 为达到设计的风场反演精度, 要求其系统定标精度达到0.5dB. 利用不同区域自然扩展目标对HY-2 SCAT进行在轨外定标, 并与OSCAT散射计在同时期内的测量结果进行了对比. 定标结果显示可以消除因散射计天线指向偏差带来的方位向测量误差. 针对HY-2 SCAT方位向测量偏差进行了误差分析, 利用仿真方法以及海洋二号卫星雷达高度计同期测量数据的反演结果进行比对, 验证了误差来源.

In-orbit Calibration of Haiyang-2 Scatterometer Using Natural Land-extended Targets

The scatterometer onboard Haiyang-2 satellite (HY-2 SCAT) is a rotating pencil-beam scatteromter. It provides 4 times of radar cross-section (σ0) measurements at different azimuth/incidence angles over a wind vector cell, in order to determine the near-surface wind field using the Geophysical Model Function (GMF). To achieve the required wind vector accuracy, radar cross-section measurements must be calibrated within a few tenths of a decibel (within 0.5dB). In this paper, HY-2 SCAT is calibrated using natural land-extended targets over different regions and is compared with OSCAT. σ0 errors over different azimuth angles are eliminated. The error sources of the measurements are analyzed and the pointing errors are compared with that estimated from measurements of Altimeter onboard HY-2 satellite.