Global Gravity Field Solutions Based on a Simulation Scenario of GRACE SST Data and Regional Refinements by GOCE SGG Observations
GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) has the potential of deriving the global gravity field with unprecedented accuracy in the high resolution spectral part. The usual way is to model the gravity field by spherical harmonics up to a degree limited by the numerical stability of the recovery procedure. A disadvantage of this kind of gravity field representation is the lack of flexibility in modeling the inhomogeneous gravity field of regions with variable rough gravity field features. An alternative approach is to determine a global gravity field solution with high long and medium wavelength accuracy, e.g. based on GRACE SST observations up to a moderate degree, and improve this global solution in regions with characteristic gravity field features by an adapted regional recovery procedure. The individual gravity field features in these regions can be modeled by space localizing base functions like spherical spline functions. The advantage of this method is the possibility of adjusting the spline representation and the recovery procedure according to the regional gravity field structures and the specific data distribution. As a first indicator of a rough gravity field the structure of the topography or geophysical apriori information can be used as a criterium. The resolution of the regional gravity field can be further improved by a subsequent iteration step. If neccessary, several regional solutions with global coverage can be merged by means of quadrature methods to obtain a global solution. Simulation results are presented to demonstrate this approach. Due to the regionally adapted recovery strategies this method provides better results than calculating a spherical harmonics solution by recovering the potential coefficients directly.
KeywordsGOCE GRACE gravity field recovery regional solutions space localizing base functions Gauss-Legendre-Quadrature
Unable to display preview. Download preview PDF.
- European Space Agency (1999) Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE). Report for mission selection, in The four candidate Earth explorer core missions, SP-1233 (1), Nordwijk, The Netherlands.Google Scholar
- Freeden W, Gervens T, Schreiner M (1998) Constructive Approximation on the Sphere. Oxford University Press, Oxford.Google Scholar
- Ilk KH, Feuchtinger M, Mayer-Guerr T (2003) Gravity Field Recovery and Validation by Analysis of Short Arcs of a Satellite-to-Satellite Tracking Experiment as CHAMP and GRACE, accepted for publication in the IAG proceedings of the General Assembly of the IUGG 2003, Sapporo, Japan.Google Scholar
- Lemoine FG, Kenyon SC, Factor JK, Trimmer RG, Pavlis NK, Chirm DS, Cox CM, Klosko SM, Luthcke SB, Torrence MH, Wang YM, Williamson RG, Pavlis EC, Rapp RH, Olson TR (1998) The development of the joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) geopotential model EGM96. NASA/TP-1998-206861, Goddard Space Flight Center, Grenbelt, MD.Google Scholar
- Mayer-Guerr T, Ilk KH, Eicker A (2003) Regional Gravity Field Recovery from GOCE Gradiometer Measurements and SST-high-low Observations — a Simulation Study. Proceedings of the 1 st Workshop on International Gravity Field Research 2003, Graz, Austria.Google Scholar
- Sneeuw N (1994) Global Spherical Harmonic Analysis by Least Squares and Numerical Quadrature Methods in Historical Perspective. Geophys. J. Int., 118: 707–716.Google Scholar
- Stroud AH, Secrest D (1966) Gaussian Quadrature Formulas. Prentice-Hall, Englewood Cliffs, N.J.Google Scholar
- Tapley BD, Bettadpur S, Watkins M, Reigber C (2004) The gravity recovery and climate experimant: mission overview and early results. Geophys Res Lett 31, L09607: doil0.1029/2004GL019920.Google Scholar