本文在简述海洋二号(HY-2A)星载微波散射计（简称散射计）工作原理的基础上，详细阐述了散射计数据预处理所涉及的关键技术，主要包括几何定位算法和雷达后向散射系数的计算。星载微波散射计数据的地理定位是计算遥感器观测点在地基坐标系中坐标的处理过程。地理定位需要考虑仪器扫描几何、空间位置、天线指向、地球曲率、旋转等因素。传统的遥感数据定位方法依赖于卫星轨道，定位精度难以保障，HY-2A卫星搭载了GPS传感器，提供1 s间隔的卫星平台定位数据，据此建立传感器观测几何与地面面元之间的几何模型，通过模型的解算获得观测面元中心的地理坐标，并计算观测面元的方位角、入射角等参数。随后采用参量代换法从雷达回波信号中计算后向散射系数。

This paper describes the key technologies involved in the scatterometer data preprocessing, which include the geometric positioning algorithm and the radar backscatter coefficient calculation algorithm. The geometric positioning of space-borne scatterometer data is a process of obtaining the coordination of measuring pulse, which needs to consider the instrument scan geometry, spatial location, antenna pointing, earth curvature, rotation, and other factors. The traditional method of geometric positioning of space-borne scatterometer data depends on the satellite ephemeris with a low positioning accuracy. HY-2A satellite is equipped with a global positioning system(GPS) sensor to provide the location of the satellite platform with 1 s interval. Accordingly, the geometric relationship between sensor observation and ground surface can be established. The geographic coordination of the observation cell center, observation azimuth angle and incidence angle can be determined using this geometric relationship. The radar backscatter coefficient is calculated with a parameter substitution method.

张 毅（1983―），男，江苏大丰市人，助理研究员，博士，主要从事微波海洋遥感研究