Observing our Changing Earth pp 493-500 | Cite as
Analysis of Geophysical Variations of the C20 Coefficient of the Geopotential
Abstract
The temporal variations of the C20 spherical harmonic coefficient of the geopotential are estimated from the length of day (LOD) and compared with the C20 variations due to geophysical contributions. In particular, we analyzed the agreement of the hydrological C20 changes as estimated by the Land Dynamics Model (LaD) model. The computation spans between January 1980 and May 2004 for the hydrological model
The contribution of atmospheric mass redistributions, along with the oceanic mass terms and solid Earth tides were removed from the geodetic C20 time series for computing residuals. Afterward the hydrological influence was investigated
After eliminating seasonal variations, the hydrological excitation seems to be not adequate to explain the inter-annual variations found in the C20 residuals
The luni-solar precession and nutation of the Earth depend on the dynamical flattening (H); which is related to the principal moments of inertia of the whole planet. H is linked to the C20 coefficient of the Earth’s potential, which is regularly determined by space geodetic techniques
In this work, we also estimate the seasonal variations on H due to geophysical causes. These results should be useful to investigate the geophysical considerations in the computation of the IAU 2000 precesion-nutation model
Keywords
Length-of-day Hydrology Geopotencial Gravity Earth rotationPreview
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