海洋二号卫星散射计海面风场观测误差全链路定量分析方法研究

Currently, there is a strong need of improving the quality of the HY-2A scatterometer wind product, which is severe restricted by the shortage of the support of full-path error analysis method. To meet these requirements, this study dedicates to establish a quantitative analysis algorithm of full-path errors for HY-2 scatterometer wind products.To construct a full-path simulation model for HY-2A scattrometer, the geometric model, radiative transfer model, geophysical model, wind vector cell regrouping model and wind field retrieval model will be analyzed. In this case, all the aspects in the manufacture of wind product can be covered by the full-path model, which contains the principles of wind observation, work conditions for the scatterometer, the environmental of the observation target, satellite platform and the track conditions, data transmission and data processing and so on.Once the full-path simulation model for HY-2A scattrometer is established, the mechanism of when, where and why the wind products error arise can be analyzed. At the same time, these errors in wind products can be quantitative analysis, so that the quantitative distribution for the error of wind product can be constructed.As a benefit of this project, the full-path simulation model as well as the quantitative distribution for the error of wind product established can provide theoretical basis for the enhancement of wind retrieval algorithm. Also, it can be used as an evaluation tools to design HY-2B scatterometer system as well to the judge whether the performance of the system can meet the required index or not.

本申请项目拟针对当前散射计全链路误差分析方法缺乏的现状以及自主卫星产品质量提高的需求，以海洋二号微波散射计为例，开展海洋二号卫星散射计海面风场观测误差全链路定量分析方法研究，构建以卫星轨道参数、姿态参数、载荷工作参数、被测地区环境参数等为输入，涵盖卫星载荷系统参数、卫星系统参数、环境参数及海面风场反演的全链路模型。在此基础上，利用全链路观测模型，对散射计风场观测全链路定量化误差产生与传递机制分析研究，并对载荷系统的指向精度、定标精度、辐射观测精度等系统特性与卫星系统的姿态稳定度、定位精度等参数对最终风场观测产品的精度影响进行定量分析，建立风场观测全链路定量化误差分配表，为散射计论证、载荷设计和反演算法选择等提供理论依据和技术支持。

项目针对目前自主卫星散射计误差分析方法与分析数据缺乏等问题，开展了相关研究，建立了全链路仿真模型，摸清误差产生和传递机制，并构建了定量化全链路误差分配表。.通过几何观测、辐射观测、地球物理、面元匹配与风场反演等模型的构建，建立了全链路仿真分析模型，并利用HY-2卫星散射计实测数据验证了仿真模型的有效性。在此基础上，分别对散射计观测级与反演级误差进行定量化仿真分析，并拓展到极化散射计。仿真分析结果表明：当卫星姿态误差优于0.1°时，入射角误差基本在±0.1°以内，观测方位角误差基本在±0.15°以内；内波束的距离向定位误差基本在±3km以内，外波束的距离向定位误差基本在±4km以内；内波束和外波束的方位向定位误差基本在±2km以内；sigma0观测结果在2dB的高斯噪声条件下，风速均方根误差为0.98m/s，风向均方根误差为6.91°；入射角观测结果在2°的高斯噪声条件下，风速均方根误差为0.47m/s，风向均方根误差为4.33°；入射角观测结果在10°的高斯噪声条件下，入风速均方根误差为0.37m/s，风向均方根误差为4.15°；将仿真模型拓展到极化散射计，并进行仿真分析，结果表明，当使用HH+VV+VHHH+HVVV极化配置时，极化仿真反演的风向结果优于同样使用SeaWinds散射计系统参数的同极化仿真10°以上。利用上述仿真结果，结合对实测数据统计分析结果，从业务化运行的角度，筛选出内定标值、天线转速等观测级质量控制指标，以及MLE均值、第一解为最终解的比率等反演级质量控制指标，构建了散射计质量控制方法。.本研究成果已应用到海洋二号B卫星地面系统业务化数据处理中，为散射计产品反演算法的改进、质量标识的设定、产品质量的提高提供理论依据；并对后续海洋二号系列卫星，以及新一代海洋动力卫星的的总体设计与卫星系统对应用指标满足程度提供理论依据和评价手段。