The static gravitational model GO_CONS_GCF_2_TIM_R6 Is the 6th release of the GOCE gravity field model by means of the time-wise approach.
GOCE Input Data:
- Gradients: EGG_NOM_2 (re-calibration, released 2018, version 0202)
- Orbits:-- SST_PKI (kinematic orbits); SST_PCV (variance information of kinematic orbit positions),-- SST_RNX (original RINEX orbit data)
- Attitude: EGG_IAQ_2C- Non-conservative accelerations: EGG_CCD_2C- Data period: 09/10/2009 - 20/10/2013
No static a-priori gravity field information applied (neither as reference model, nor for constraining the solution)
Processing procedures:
- Gravity from orbits (SST):- short-arc integral method applied to kinematic orbits, up to degree/order 150- orbit variance information included as part of the stochastic model, it is refined by empirical covariance functions
- Gravity from gradients (SGG):- parameterization up to degree/order 300- observations used: Vxx, Vyy, Vzz and Vxz in the Gradiometer Reference Frame (GRF)- realistic stochastic modelling by applying digital decorrelation filters to the observation equations; estimated separately for individual data segments applying a robust procedure
- Combined solution:- addition of normal equations (SST D/O 150, SGG D/O 300)- Constraints: Kaula-regularization applied to coefficients of degrees/orders 201 - 300 (constrained towards zero) observation equations for zero gravity anomaly observations in polar regions (>83°) to constrain polar gaps towards zero (degree 11 to 300)
- Optimum weighting (SST, SGG, constraints) based on variance component estimation
Specific features of resulting gravity field:- Gravity field solution is independent of any other gravity field information- Constraint towards zero starting from degree/order 201 to improve signal-to-noise ratio- Related variance-covariance information represents very well the true errors of the coefficients- Solution can be used for independent comparison and combination on normal equation level with other satellite-only models (e.g. GRACE), terrestrial gravity data, and altimetry- Since in the low degrees the solution is based solely on GOCE orbits, it is not competitive with a GRACE model in this spectral region is available via this data publication and via ICGEM (Ince et al., 2019). Link to ICGEM Website: http://icgem.gfz-potsdam.de- The reference epoch is 2010-01-01 (MJD 55197)
Further processing details can be found in Brockmann (2014), Brockmann et al. (2014) Mayer-Gürr et al. (2005) and Pail et al. (2014).