Using Marine Data to Estimate the Accuracy of Free Air Gravity Anomaly Models Derived From Satellite Altimetry

Abstract

Global gravity models from satellite altimetry missions have widely contributed to the improvement of the knowledge over the oceans. However, few models are available with a validated accuracy model, as the most recent models V21 to V32 from Scripps Institution of Oceanography (SIO). The aim of this paper is to propose a method to estimate the accuracy of any free air gravity anomaly model derived from satellite altimetry from validated marine data sets. The main idea is to correlate the error of the model to the mean roughness of the free air gravity anomaly on precise marine measurement areas. The relationship obtained is then generalized to each point of the model. This error grid is eventually combined with the grid provided by the satellite models, reflecting the errors related to the technology of the different altimetry satellites used. The method has been successfully applied to successive versions of SIO gravity anomaly models (from V18 to V31) to produce continuous accuracy grids over the North Atlantic Ocean. Validation of the results from independent marine data shows that the proposed approach allows to strongly improve the estimation of the used models' accuracy which converges, whatever the tested versions, toward a minimal value of 0.9 mGal over flat areas.

Potential of cold-atom airborne gravimetry to improve coastal gravity field and quasigeoid modelling

“…With an observed SD of around 3 mGal between altimetric models and GIRAFE observations over sea, this means that the accuracy of the altimetric models must be around 2.5-2.8 mGal in the study area. This accuracy of the altimetric models is consistent with Rouxel et al (2023), in which they were compared with shipborne gravity data on the Atlantic Ocean.…”

Zones of Weakness Within the Juan de Fuca Plate Mapped From the Integration of Multiple Geophysical Data and Their Relation to Observed Seismicity

“…In particular, Sandwell et al (2021) used a very precise marine gravity survey data set in the Gulf of Mexico to compute the median deviation between satellite and marine data sets of 1.33 mGal. Rouxel et al (2023) compared satellite gravity with several marine gravity surveys over the Atlantic Ocean and concluded a dispersion between data sets within 1 mGal starting from satellite version 23 (we use version 29.1). Therefore, the observed local gravity anomalies such as local gravity lows up to ∼15 mGal and around 10-25 km wide over the known PWs (Figure 2a) are real and require geological explanations.…”