Thursday 25 August 2005

G2
1330-1500 hours

384
Recovery of the Earth's gravity field from a combination of SST data from the GOCE, GRACE and CHAMP missions: A simulation study
Abrikosov, Oleh¹, Schmidt, Roland¹, Flechtner, Frank¹, König, Rolf¹, Rothacher, Markus¹, Neumayer, Karl-Hans¹, Reigber, Christoph¹
1 Department 1 Geodesy And Remote Sensing, GeoForschungsZentrum Postdam (GFZ), Germany
Author email: rschmidt@gfz-potsdam.de
On the basis of GOCE SST data simulated along a 30-day perturbed orbit, we numerically assessed two sources of errors contaminating the results of Earth gravity field determination. These are polar gaps and the uneven distribution of the data over altitude. A combined effect of these irregularities in the GOCE data distribution can produce errors in the harmonic coefficients of very first orders which are responsible for more than 95% of the total geoid errors over the Earth's surface. Moreover, up to 90% of the total geoid errors are concentrated in both polar areas, and the magnitude of the geoid errors can differ by a factor of 2-3 between the polar areas. In order to suppress the mentioned errors, we examined two different approaches. The first consists of the weighting of the GOCE SST observation equations whereas the second approach is based on the synthesis of the SST data coming from the GOCE, GRACE and CHAMP missions. We show that these errors in the determination of the Earth's gravity field can be reduced to a large extent (up to 10 times) by both of these approaches. However, the best results in terms of true errors of the recovered gravity model were obtained from the combination of the two approaches.

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