遥感卫星载荷海洋耀斑观测几何模型研究

The Research of Sun Glint Observation Geometry Model for Remote Sensing Satellite

为研究遥感卫星观测海洋耀斑时耀斑观测角度及耀斑长度的变化规律,为遥感载荷视场设计提供基础参考数据,文章在假设海洋表面完全反射的基础上,建立了卫星载荷海洋耀斑观测的完全几何模型,确定了卫星观测海洋耀斑的镜面反射极限位置,并建立方程组求取耀斑观测边缘视场指向角,以此获取耀斑观测角和耀斑长度。结合轨道仿真软件(Satellite Tools Kit,STK),以夏至日和冬至日的太阳同步轨道为算例,完成边缘视场耀斑观测指向角、耀斑观测角、耀斑长度的计算。结果表明,耀斑观测参数呈现明显的轨道周期特性,两个耀斑观测边缘指向角在冬至日和夏至日变化趋势相似,但变化范围不同;耀斑观测角呈类正弦变化,最大约为0.43°;耀斑长度夏至日时在0~29.2km范围内变化,冬至日时在0~29.7km范围内变化。通过STK软件生成的耀斑观测指向角与文章模型生成的耀斑观测边缘视场指向角进行对比验证,表明耀斑观测几何模型正确、合理,可为卫星遥感载荷的海洋耀斑观测或规避提供理论依据和边界条件。

In order to research the remote sensing satellite variation law of viewing angles and length for sun glint and supply the basic data for instrument viewing geometry, sun glint observation geometry model for remote sensing satellite was built up and the boundary position of sun glint viewing angles was found based on the assumption of the total mirror reflection on the ocean. Then the equations for the boundary angles of sun glint direction were given and the viewing angles and length of sun glint were obtained. With the aid of satellite orbit simulation software（Satellite Tools Kits, STK）, the boundary angles of sun glint direction, the viewing angles and the length of sun glint were calculated in the condition of sun-synchronous orbit at summer solstice and winter solstice. The results show that these sun glint observation parameters present obvious characteristics of orbital period. The boundary angles of sun glint direction have similar variation trend in the sinusoidal wave with different ranges. The maximum viewing angles of sun glint is 0.43 approximately. The length of viewing sun glint for summer solstice and winter solstice are varying between 0～29.2 km and 0～29.7 km respectively. By comparison and validation with the STK sun glint calculation results, the sun glint observation geometry model presented in this paper is rational and correct,which can provide the theoretical basis and boundary condition of the sun glint observation or avoidance for remote sensing satellite.