Model Characteristics ---------------------- GOCE Input Data: - Gradients: EGG_NOM_2 - Orbits: SST_PKI (kinematic orbits) - Attitude: EGG_IAQ_2C - Data period: 20091101T000000:20100630T235959 The full list of input data to this direct-approach model is provided in the IHD file. A-priori Information used: - A-priori gravity field information applied Background model: ITG-Grace2010s (Mayer-Guerr et al. 2010) up to d/o 150 Processing Procedures: - The orbit positions of the GO_CONS_SST_PKI 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 150. - The gravity gradients are processed without applying the calibration factors. The observation equations are filtered with a 10-125 mHz 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 0.00001, Txx, Tyy and Tzz 1.0. The contribution of the SST normal equation was taken only to d/o 130. - To overcome the numerical instability of the normal equations due to the polar gaps a spherical cap regularization in accordance to Metzler and Pail (2005) was iteratively computed to d/o 240 using the GRACE gravity field model ITG-Grace2010s (Mayer-Guerr et al. 2010) to d/o 150. - 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 model is a satellite-only model. Due to the applied polar gap stabilization it is mainly based on GRACE data up to d/o 150 Processing details are presented in Bruinsma et al. 2010 and Pail et al. 2011. 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 - Mayer-Guerr T., Kurtenbach E. and Eicker A., 2010, The Satellite-only Gravity Field Model ITG-Grace2010s, http://www.igg.uni-bonn.de/apmg/index.php?id=itg-grace2010 - Metzler B. and Pail R., 2005, GOCE Data Processing: The Sperical Cap Regularization Approach, Stud. Geophys. Geod. 49 (2005), 441-462 - Pail R., Bruinsma S., Migliaccio F., Foerste C., Goiginger H., Schuh W.-D, Hoeck E, Reguzzoni M., Brockmann J.M, Abrikosov O., Veicherts M., Fecher T., Mayrhofer R., Krasbutter I., Sanso F. and Tscherning C.C., 2011, First GOCE gravity field models derived by three different approaches. Jounal of Geodesy, in review.