TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 64 (No. 7), pp. e21-e24, 2012


Bathymetric stripping corrections to gravity gradient components

Robert Tenzer1 and Pavel Novák2

1School of Surveying, University of Otago, 310 Castle Street, Dunedin, New Zealand
2NTIS - New Technologies for Information Society, University of West Bohemia, Univerzitní 22, Plzeň, Czech Republic

(Received April 11, 2012; Revised June 15, 2012; Accepted July 2, 2012; Online published August 16, 2012)

Abstract: To allow for geophysical interpretation of observed gravity gradients, several corrections must be applied. In this article expressions for gravimetric forward modeling of bathymetric (ocean density contrast) stripping corrections to GOCE gravity gradient observables are evaluated numerically. The generic expression for the bathymetric gravitational potential utilizes a depth-dependent seawater density distribution model. The expressions are defined in their spectral representation by means of the bathymetric spherical functions which describe the global geometry of the ocean bottom relief. Numerical examples are given for the bathymetric stripping corrections to selected gravity field parameters computed with a spectral resolution complete to degree 360 of spherical harmonics. All computations are realized globally on the 1 arc-deg geographical grid at the mean satellite elevation of 250 km. The results reveal that the bathymetric stripping corrections to gravity gradients globally vary within ±5 × 10-9 s-2. Extreme values apply mainly along the continental margins where the largest spatial bathymetric gravitation signal variations occur.
Key words: Bathymetry, forward modeling, GOCE, gravitational gradiometry, ocean density contrast.

Corresponding author E-mail: robert.tenzer@otago.ac.nz

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