| Abstrakt: |
High-precision geocentric coordinates (GCC) play a crucial role in geophysical research, and can be derived as a by-product of Global Navigation Satellite System (GNSS) Precise Orbit Determination (POD). As a newly built global system, BDS-3 (BeiDou Navigation Satellite System) has already achieved high orbital accuracy in POD, which is a benefit for estimating geocenter coordinates. During the POD process, the orbital error caused by solar radiation pressure (SRP) is hardly accurately modeled, which affects both POD and parameter estimation accuracy. Our goal is an orbital plane-related SRP error correction model to improve POD accuracy and achieve high geocentric coordinate accuracy. First, the correlation characteristics between the Z-direction of GCC coordinates (GCC-Z) and ECOM2 (The Empirical CODE (Center for Orbit Determination in Europe) Orbit Model) parameters are discovered from experimental comparisons. Then, the plane-specific orbit error correction model is proposed and applied in POD process. With the improved model, the correlations between estimates are mitigated and the orbit accuracies have improved by 23.7, 24.4, and 25.5% for MEOs (Medium Earth Orbits), and by 24.9, 16.1, and 19.6% for IGSOs (Inclined GeoSynchronous Orbits) in the radial, along-track, and cross-track components, respectively. In addition, the mean formal error of GCC-Z was significantly reduced from 3.6 to 1.7 mm, and most periodic fluctuations have also been eliminated. Finally, spectral analysis is performed for the enhanced GCC time series based on the plane-specific model. Compared with ECOM2, the peak-to-peak variations of GCC are decreased to less than 15 cm, and 1-cpy (cycle per year), 3-cpy, and 7-day periodic terms are detected with smaller amplitudes. [ABSTRACT FROM AUTHOR] |
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