Tuesday 23 August 2005

G2
1330-1525 hours

167
About some problems related to the inversion of airborne gravity data
Alberts, Bas¹, Ditmar, Pavel¹, Klees, Roland¹
1 Delft Institute of Earth Observation and Space Systems (DEOS), Delft, The Netherlands
Author email: b.a.alberts@lr.tudelft.nl
For many applications in gravity field modelling, the resolution of satellite only models derived from current and future satellite missions will not be sufficient. The most suitable technique to determine the short-wavelength information is airborne gravimetry, since it can provide gravity observations in an efficient way. For the processing of airborne gravity measurements and the inversion into gravity field functionals, e.g. geoid heights, a new methodology is under development. It is based on a spectral representation of the Earth's gravity field. The gravitational potential is parameterized as a linear combination of harmonic functions, which are fundamental solutions of Laplace's equation in Cartesian coordinates. The parameters of this representation are estimated using least-squares techniques. With the chosen representation the gravity signal is assumed to be periodic, which clearly does not hold for regional computations. Discontinuities at the edges of the area cause strong oscillations, that propagate into the area. We investigated several approaches to reduce these edge effects, using simulated high-frequency data sets. Because the low-frequency information cannot be recovered from airborne gravity data, the airborne solution is combined with a global gravity model. Nevertheless, when we compute geoid heights from airborne gravity disturbances, the solution gets distorted by low-frequency artifacts, which cannot be explained physically. In order to solve this problem, we propose to add either hard or weak constraints to the functional model.

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