Combining atmospheric and non-tidal ocean loading effects to correct high precision gravity time-series

authored by
E. D. Antokoletz, H. Wziontek, H. Dobslaw, K. Balidakis, T. Klügel, F. A. Oreiro, C. N. Tocho
Abstract

In modelling atmospheric loading effects for terrestrial gravimetry, state-of-the-art approaches take advantage of numerical weather models to account for the global 3-D distribution of air masses. Deformation effects are often computed assuming the Inverse Barometer (IB) hypothesis to be generally valid over the oceans. By a revision of the IB assumption and its consequences we show that although the seafloor is not deformed by atmospheric pressure changes, there exists a fraction of ocean mass that current modelling schemes are usually not accounting for. This causes an overestimation of the atmospheric attraction effect over oceans, even when the dynamic response of the ocean to atmospheric pressure and wind is accounted through dynamic ocean models. This signal can reach a root mean square variability of a few nm s-2, depending on the location of the station. We therefore test atmospheric and non-tidal ocean loading effects at five superconducting gravimeter (SG) stations, showing that a better representation of the residual gravity variations is found when Newtonian attraction effects due to the IB response of the ocean are correctly considered. A sliding window variance analysis shows that the main reduction takes place for periods between 5 and 10 d, even for stations far away from the oceans. Since periods of non-tidal ocean mass variability closely resemble atmospheric signals recorded by SGs, we recommend to directly incorporate both an ocean component together with the IB into services that provide weather-related corrections for terrestrial gravimetry.

External Organisation(s)
Federal Agency for Cartography and Geodesy (BKG)
Universidad Nacional de La Plata
CONICET
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
Servicio de Hidrografía Naval (SHN)
Type
Article
Journal
Geophysical journal international
Volume
236
Pages
88-98
No. of pages
11
ISSN
0956-540X
Publication date
01.2024
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Geophysics, Geochemistry and Petrology
Electronic version(s)
https://doi.org/10.1093/gji/ggad371 (Access: Open)