Consistency of Geoid Models, Radar Altimetry, and Hydrodynamic Modelling in the North Sea. Issue 3 (3rd July 2016)

• Record Type: Journal Article
• Authors: Schall, J.; Löcher, A.; Kusche, J.; Rietbroek, R.; Sudau, A.
• Is Part Of: Marine geodesy. Volume 39:Issue 3/4(2016)
• Page Start: 223
• Page End: 237
• Publication Date: 2016-07-03
• Subjects: Geoid models -- hydrodynamic modelling -- North Sea -- radar altimetry; Marine geodesy -- Periodicals; Hydrographic surveying -- Periodicals; 526.99
• DOI: 10.1080/01490419.2016.1152334
• Languages: English
• ISSNs: 0149-0419

Abstract

ABSTRACT: Radar altimetry, when corrected for tides, atmospheric forcing of the sea surface, and the effects of density variations and mean and time-variable currents, provides an along-track realization of the marine geoid. In this study we investigate whether and how such an 'altimetric-hydrodynamic' geoid over the North Sea can serve for validating satellite-gravimetric geoids. Our results indicate that, using ERS-2 and ENVISAT along-track altimetry and water levels from the high-resolution operational circulation model BSHcmod, we do find distinct differences in RMS fits for various state-of-the art satellite-only models (beyond degree 145 for GRACE-only, and beyond degree 185 for GOCE models) and for combined geoid models, very similar as seen in GPS-levelling validations over land areas. We find that, at spectral resolution of up to about 200, an RMS fit as low as about 7 cm can be obtained for the most recent GOCE-derived models such as GOCO05S. This is slightly above what we expect from budgeting individual errors. Key to the validation is a proper treatment of the spectral mismatch between satellite-gravimetric and altimetric-hydrodynamic geoids. Comparison of data fits and error budget suggests that geoid truncation errors residual to EGM2008 (i.e. EGM2008 commission and omission error) may amount up to few cm.