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

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.

[1]  O. Andersen,et al.  Gravity recovery from SWOT altimetry using geoid height and geoid gradient , 2021 .

[2]  Walter H. F. Smith,et al.  The Generic Mapping Tools Version 6 , 2019, Geochemistry, Geophysics, Geosystems.

[3]  Walter H. F. Smith,et al.  Gravity field recovery from geodetic altimeter missions , 2019, Advances in Space Research.

[4]  S. Holmes,et al.  Evaluation of the Global Altimetric Marine Gravity Field DTU15: Using Marine Gravity and GOCE Satellite Gravity , 2019, International Symposium on Advancing Geodesy in a Changing World.

[5]  Mostafa Rabah,et al.  Comparison of Satellite Altimetric Gravity and Global Geopotential Models with Shipborne Gravity in the Red Sea , 2018 .

[6]  David T. Sandwell,et al.  Retracking of SARAL/AltiKa Radar Altimetry Waveforms for Optimal Gravity Field Recovery , 2017 .

[7]  M. Sharifi,et al.  Improved gravity anomaly fields from retracked multimission satellite radar altimetry observations over the Persian Gulf and the Caspian Sea , 2015 .

[8]  Walter H. F. Smith,et al.  New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure , 2014, Science.

[9]  D. Sandwell,et al.  Significant improvements in marine gravity from ongoing satellite missions , 2013, Marine Geophysical Research.

[10]  Walter H. F. Smith,et al.  Toward 1-mGal accuracy in global marine gravity from CryoSat-2, Envisat, and Jason-1 , 2013 .

[11]  P. Keating,et al.  Comparison of surface and shipborne gravity data with satellite- altimeter gravity data in Hudson Bay , 2013 .

[12]  Bertrand Chapron,et al.  Global Observations of Fine-Scale Ocean Surface Topography With the Surface Water and Ocean Topography (SWOT) Mission , 2010, Front. Mar. Sci..

[13]  J. Edwards,et al.  A method of error adjustment for marine gravity with application to Mean Dynamic Topography in the northern North Atlantic , 2009 .

[14]  Walter H. F. Smith,et al.  Global marine gravity from retracked Geosat and ERS‐1 altimetry: Ridge segmentation versus spreading rate , 2009 .

[15]  A. B. WATTS,et al.  Isostasy and Flexure of the Lithosphere , 2001 .

[16]  R. Rapp,et al.  Role of ocean variability and dynamic ocean topography in the recovery of the mean sea surface and gravity anomalies from satellite altimeter data , 1997 .

[17]  Walter H. F. Smith,et al.  Marine gravity anomaly from Geosat and ERS 1 satellite altimetry , 1997 .

[18]  D. Sandwell,et al.  A comparison of satellite and shipboard gravity measurements in the Gulf of Mexico , 1992 .

[19]  M. Diament,et al.  An analysis of the altimetric geoid in various wavebands in the Central Pacific Ocean: constraints on the origin of intraplate features , 1991 .

[20]  D. Gibert,et al.  The geoid roughness: A scanner for isostatic processes in oceanic areas , 1990 .

[21]  A. Watts,et al.  On the accuracy of marine gravity measurements , 1988 .

[22]  D. Gibert,et al.  Seasat Altimetry and the South Atlantic Geoid: 1. Spectral analysis , 1987 .

[23]  Dennis E. Hayes,et al.  Quantitative Methods for Analyzing the Roughness of the Seafloor (Paper 5R0105) , 1985 .

[24]  M. Nabighian.  Toward a three‐dimensional automatic interpretation of potential field data via generalized Hilbert transforms: Fundamental relations , 1984 .

[25]  W. E. Himwich,et al.  Roughness of the marine geoid from SEASAT altimetry , 1983 .

[26]  Misac N. Nabighian,et al.  The analytic signal of two-dimensional magnetic bodies with polygonal cross-section; its properties and use for automated anomaly interpretation , 1972 .

[27]  Ronald N. Bracewell,et al.  The Fourier Transform and Its Applications , 1966 .

[28]  S. Bruinsma,et al.  Exploitation of Marine Gravity Measurements of the Mediterranean in the Validation of Global Gravity Field Models , 2016 .

[29]  Christine Gommenginger,et al.  Retracking Altimeter Waveforms Near the Coasts , 2011 .

[30]  M. Sinha.  Ship-based Trackline Geophysical Data (MGD77) acquired during the Maurice Ewing expedition EW9512 (1995) , 2010 .

[31]  Markus Roland,et al.  Compilation and Evaluation of a Consistent Marine Gravity Data Set Surrounding Europe , 2005 .

[32]  A. Cazenave,et al.  Satellite altimetry and earth sciences : a handbook of techniques and applications , 2001 .

[33]  M. Maia,et al.  Roughness of the gravity and seafloor topography used to infer geodynamic settings , 1999 .

[34]  D. Sandwell,et al.  What are the limitations of satellite altimetry , 1998 .

[35]  Walter R. Roest,et al.  Magnetic interpretation using the 3-D analytic signal , 1992 .