GOCE Gravity Field Model

Direct Solution - First generation

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Model Characteristics
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GOCE Input Data:
- Gravity gradients, reduced dynamic orbits and attitude from combined star tracker
and gradiometer observations.
- Data period: 20091101T000000:20100111T235959
		
A-priori Information used:
- A-priori gravity field information applied Background model: EIGEN5C
(Foerste et al. 2008) up to d/o 360
		
Processing Procedures:
- The orbit positions of the GO_CONS_SST_PRD product are used as observations in a
reduced-dynamic orbit computation procedure, which uses the measured common mode
accelerations too. "SST" Normal equations are computed to d/o 120.
- The gravity gradients are processed without applying the calibration factors. The
observation equations are filtered with a (100-8) seconds bandpass filter, and
subsequently "SGG" normal equations to d/o 240 are computed individually for the
gradient components Txx, Tyy and Tzz.
- The SST and SGG normal equations are accumulated with the following relative
weights: SST 0.05, Txx 1.0, Tyy 0.5 and Tzz 1.0. The contribution of the SST
normal equation was taken only till d/o 110.
- To overcome the polar gaps a spherical cap stabilization in accordance to Metzler
and Pail (2005) is computed to d/o 240 using the combinned gravity field model
EIGEN-51C (Bruinsma et al. 2010).
- The solution was obtained by Cholesky decomposition of the accumulated normal
equations
	
Specific features of resulting gravity field:
- The model is more accurate than state-of-the-art GRACE models for degrees 130-150
and up, but less accurate for the lower degrees.
- The significant errors present in combined gravity field models over
South America, Africa and Asia due to poor data are not observed.
	
References:
- Bruinsma S.L., Marty J.C., Balmino G., Biancale R., Foerste C.,
Abrikosov O. and Neumayer H, 2010, GOCE Gravity Field Recovery by Means
of the Direct Numerical Method, presented at the ESA Living Planet Symposium,
27th June - 2nd July 2010, Bergen, Norway; See also: earth.esa.int/GOCE
- Foerste C, Flechtner F, Schmidt R, Stubenvoll R, Rothacher M, Kusche J, Neumayer H,
Biancale R, Lemoine J-M, Barthelmes F, Bruinsma S, Koenig R and Meyer Ul, 2008,
EIGEN-GL05C - A new global combined high-resolution GRACE-based gravity field
model of the GFZ-GRGS cooperation, Geophysical Research Abstracts, Vol. 10,
EGU2008-A-03426, 2008 SRef-ID: 1607-7962/gra/EGU2008-A-03426
The EIGEN-5C model is available at the ICGEM data base at
http://icgem.gfz-potsdam.de/ICGEM/
- Metzler B. and Pail R., 2005, GOCE Data Processing: The Sperical Cap Regularization
Approach, Stud. Geophys. Geod. 49 (2005), 441-462