Do We Need New Gravity Field Recovery Techniques for the New Gravity Field Satellites?
The classical approach of satellite geodesy consists in deriving the spherical harmonic coefficients representing the gravitational potential from an analysis of accumulated orbit perturbations of artificial satellites with different altitudes and orbit inclinations. This so-called differential orbit improvement technique required the analysis of rather long arcs of days to weeks; it was the adequate technique for satellite arcs poorly covered with observations, mainly precise laser ranging to satellites. The situation changed dramatically with the new generation of dedicated gravity satellites such as CHAMP, GRACE and – in a couple of months – GOCE. These satellites are equipped with very precise sensors to measure the gravity field and the orbits. The sensors provide a very dense coverage with observations independent from Earth based observation stations. The measurement concepts can be characterized by an in-situ measurement principle of the gravitational field of the Earth. In the last years various recovery techniques have been developed which exploit these specific characteristics of the in-situ observation strategy. This paper gives an overview of the various gravity field recovery principles and tries to systemize these new techniques. Alternative in-situ modelling strategies are presented based on the translational and rotational integrals of motion. These alternative techniques are tailored to the in-situ measurement characteristics of the innovative type of satellite missions. They complement the scheme of in-situ gravity field analysis techniques.
KeywordsCHAMP GRACE GOCE differential orbit improvement in-situ measurement principle integrals of motion energy integral balance equations gravity field recovery
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- Gerlach C, Földvary L, Švehla D, Gruber T, Wermuth M, Sneeuw N, Frommknecht B, Oberndorfer H, Peters T, Rothacher M, Rummel R, Steigenberger P (2003) A CHAMP-only gravity field model from kinematic orbits using the energy integral, Geophysical Research Letters (2003) 30(20), 2037.CrossRefGoogle Scholar
- Ilk KH, Feuchtinger M, Mayer-Gürr T (2003) Gravity Field Recovery and Validation by Analysis of Short Arcs of a Satellite-to-Satellite Tracking Experiment as CHAMP and GRACE, In: F. Sansò (ed.) A Window on the Future of Geodesy, IUGG General Assembly 2003, Sapporo, Japan, International Association of Geodesy Symposia, Vol. 128, pp. 189–194, Springer.Google Scholar
- Ilk KH, Löcher A (2003) The Use of Energy Balance Relations for Validation of Gravity Field Models and Orbit Determination Results, In: F. Sansò (ed.) A Window on the Future of Geodesy, IUGG General Assembly 2003, Sapporo, Japan, International Association of Geodesy Symposia, Vol. 128, pp. 494–499, Springer.Google Scholar
- Kaula WM (2000) Theory of Satellite Geodesy, Applications of Satellites to Geodesy, Dover Publications, INC, Mineola, New York.Google Scholar
- Löcher A (2006) A scheme of integrals of motion for gravity field determination based on precisely observed low Earth satellites, poster presented at the General Assembly 2006 of the EGU, April 02–07, 2006, Vienna, Austria.Google Scholar
- Löcher A, Ilk KH (2005) Energy Balance Relations for Validation of Gravity Field Models and Orbit Determinations Applied to the Results of the CHAMP Mission, In: C. Reigber, H. Lühr, P. Schwintzer, J. Wickert (Eds.) Earth Observation with CHAMP, Results from Three Years in Orbit, pp. 53–58, Springer.Google Scholar
- Löcher A, Ilk KH (2006) A Validation Procedure for Satellite Orbits and Force Function Models Based on a New Balance Equation Approach, In: Proceedings of the Internat. Symposium Dynamic Planet 2005, Monitoring and Understanding a Dynamic Planet with Geodetic and Oceanographic Tools, August 22–26, 2005, Cairns, Australia.Google Scholar
- Reubelt T, Austen G, Grafarend EW (2003) Harmonic analysis of the Earth’s gravitational field by means of semi-continuous ephemerides of a low Earth orbiting GPS-tracked satellite. Case study: CHAMP, Journal of Geodesy (2003) 77:257–278.Google Scholar