Publication Date:
2023-08-30
Description:
Low-degree gravity field solutions are of vital importance, since they are directly related to the most meaningful physical properties of the Earth (large-scale mass distribution, center of mass and inertia tensor), which define the terrestrial frame (origin and orientation). However, it is known that the GRACE/GRACE-FO C20 estimates are not reliable and have thus to be replaced by estimates from SLR. In this context, the primary goal of our analysis is to estimate the degree-2 gravity field coefficients using GNSS observations from terrestrial ground stations, which may be used as an independent comparison with existing solutions. To accomplish this purpose, we have to deal with two major difficulties: (1) due to the lower sensitivity of the GNSS satellites to the Earth’s time-variable gravity field, initial estimates are contaminated by spurious signals, and (2) C20 coefficients are strongly correlated with the length-of-the-day. The former problem may be overcome by adjusting the orbit parametrization and using a long-term stacking of normal equations. This allows to reduce artefacts and to improve the estimated gravity field coefficients. As a secondary goal, our analysis provides insight into the capability of GNSS to recover long-wavelength gravity field signals, which is a preceding step for future multi-technique-derived solutions.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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