A signal-strength model for gravity-field spectrum components in a local space

Liu Hongwei, Wang Zhaokui, Zhang Yulin

Abstract


In the Earth gravity-field model, potential coefficients are projections of the Earth gravitational potential on the corresponding spherical harmonics by degree and order. These coefficients reflect the spectral composition of the Earth gravitational potential in the whole space, but they cannot reflect the spectral composition in a local area. In this study, the Earth gravitational potential was projected on spherical harmonics in a local area using a window function introduced to facilitate the mathematical expressions. Then a model for the spectral structure of the Earth gravitational potential in the local area was established. The model can reflect the signal strength of any gravity-field spectrum component in the local area, which adds information for the description of the gravity field of the Earth, and which has great significance for Earth-sciences research and satellite gravity measurements. Taking the third-degree coefficients, for example, the signal-strength distributions of potential coefficients were computed. The data show that the signal-strength distributions of third-degree coefficients on the sphere surface are independent of the longitude. Among the third-degree coefficients, the zero-order, first-order and second-order coefficients are stronger near the two poles of the Earth, while the third-order coefficient is stronger near the equator.


Keywords


Earth's Gravitational Potential; Local Area; Spectrum Structure; Spherical Cap Harmonic Analysis;

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References


DOI: https://doi.org/10.4401/ag-5459
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X