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Free keywords:
Terrestrial gravimetry; atmospheric loading; non-tidal ocean loading; Atmacs; eOST loading service
Abstract:
Besides Earth tides, the atmosphere causes the most significant contributions to time-variable gravity. State-of-the-art modelling approaches of atmospheric loading (Newtonian attraction and deformation) benefit from numerical weather models in order to account for global air mass variations. Atmospheric loading effects are often computed assuming that the oceans respond as an Inverse Barometer (IB) which is not completely valid for periods shorter than a few weeks. Therefore, a more precise modelling is only possible considering the ocean response to atmospheric pressure and winds based on simulations of an ocean dynamic model. Superconducting gravimeters (SGs) measure temporal gravity variations with high-resolution and exceptional stability and are capable to sense mass redistribution in the atmosphere, the oceans and in terrestrial water storage. In this sense, although SGs provide information for particular sites, they allow for a reliable validation of mass variations represented by models for atmosphere and oceans. In the present study, a comparison of atmospheric and non-tidal ocean loading corrections as calculated by the recently updated Atmospheric attraction computation service (Atmacs) and the EOST Loading Service is performed. For this comparison, a set of SG stations is selected, with focus on stations close to the oceans where non-tidal ocean loading effects are more significant. An emphasis is made on the reduction of gravity residuals by different corrections.
