顾及地球曲率及椭球高的GNSS-R几何计算方法

doi:10.11947/j.AGCS.2023.20210563

摘要/Abstract

摘要： 全球卫星导航系统反射测量 (GNSS-R) 技术中,观测几何计算不仅涉及GNSS反射信号的在轨实时处理,而且与观测值的地理位置计算直接相关,对其进行精确计算十分重要。当前GNSS-R技术逐步向陆地场景拓展,已有几何计算方法难以满足多场景(海洋、陆地、冰川等)应用的需求。针对此,本文提出了一种顾及地球曲率和椭球高的几何计算方法。该方法同时也集成了一种镜面点初始估计模型,在不同轨道高度(300~900 km)和观测几何条件下,初始估计误差精度可降低至5 km以内。本文方法可基于WGS-84椭球面和顾及反射面椭球高精确计算镜面反射点,精度可控在1 mm以内,计算效率相比已有方法有显著提升,可对未来考虑地形高度的高效计算需求提供借鉴。本文方法通过变换迭代方程可进行反射信号的几何路径计算,实现从反射信号延迟观测到镜面反射点和椭球高的一体解算。与已有方法相比,本文方法考虑了地球曲率及反射点随椭球高度变化的空间偏移误差,可避免测高应用中测量值定位不准确的问题。

关键词: GNSS-R, 几何计算, 初始镜面反射点, 地球曲率, 椭球高

Abstract: Geometry computation is crucial for global navigation satellite systems reflectometry (GNSS-R), serving as a fundamental aspect for processing the reflected signals onboard and determining the measurement locations. However, the existing geometry computation methods can not meet the requirements of various scenarios, including land, ocean, and cryosphere applications, as this technique expands into new domains. This paper proposes a geometry computation strategy that achieves high accuracy and incorporates considerations for the Earth's curvature and ellipsoidal height. It integrates a initialization model for specular point calculation, and the accuracy of the initial estimation error can be reduced to within 5 km for different orbital altitudes (300~900 km) and geometric conditions. This method allows for high-precision geometry computation based on the WGS-84 ellipsoid, and takes into account the ellipsoidal height of the reflective surface, with an accuracy of less than 1 mm. The computational efficiency is significantly improved compared to existing methods, which can be beneficial for future demands of efficient computation considering surface height. Furthermore, the method can calculate the geometric path of the reflection signal by modifying the iterative equation, and achieves the integrated solution from the observed delay to the specular point and ellipsoidal height. Compared with the previous methods, it considers the Earth's curvature and the spatial offset of the reflection point varying with the ellipsoidal height, which can avoid the problem of inaccurate positioning of measurements in altimetric applications.

Key words: GNSS reflectometry, geometry computation, initial specular point estimation, Earth's curvature, ellipsoidal height

中图分类号:

P227

宋敏峰, 何秀凤, 王笑蕾, 肖儒雅, 贾东振, 李伟强. 顾及地球曲率及椭球高的GNSS-R几何计算方法[J]. 测绘学报, 2023, 52(6): 884-894.

SONG Minfeng, HE Xiufeng, WANG Xiaolei, XIAO Ruya, JIA Dongzhen, LI Weiqiang. A GNSS-R geometry computation method considering the Earth's curvature and ellipsoidal height[J]. Acta Geodaetica et Cartographica Sinica, 2023, 52(6): 884-894.

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