WHU-SWPU-GOGR2022S is a static gravity field model complete to spherical harmonic degree and order of 300 by combining GOCE and GRACE normal equations. Details of the processing procedures are as follows:
(1) Details of the GOCE processing procedures:
(1a) Input data:
-- GOCE SGG data: EGG_NOM_2 (GGT: Vxx, Vyy, Vzz and Vxz) in GRF (9/10/2009-20/10/2013)
-- GOCE SST data: SST_PKI_2, SST_PCV_2, SST_PRD_2 (9/10/2009-20/10/2013)
-- Attitude: EGG_NOM_2 (IAQ), SST_PRM_2 (PRM)
-- Non-conservative force: Common mode ACC (GG_CCD_1i)
-- Background model: tidal model (solid etc.), third-body acceleration, relativistic corrections, ...
(1b) Data progress strategies:
-- Data preprocessing
- Gross outlier elimination and interpolation (only for the data gaps less than 40s).
- Splitting data into subsections for gaps > 40s
-- The normal equation from SST data
- Point-wise acceleration approach (PAA)
- Extended Differentiation Filter (low-pass)
- Max degree: up to 130
- Data: PKI, PCV, CCD
-- The normal equation from SGG data
- Direct LS method
- Max degree: up to 300
- Data: GGT, PRD, IAQ, PRM
- Band-pass filter: used to deal with colored-noise of GGT observations (pass band 0.005-0.100Hz )
- Forming the normal equations according to subsections
- Spherical harmonic base function transformation instead of transforming GGT from GRF to LNRF
-- Combination of SGG and SST
- Max degree: up to 300
- The VCE technique is used to estimate the relative weights for Vxx, Vyy, Vzz and Vxz
- Tikhonov Regularization Technique (TRT) is only applied to near (zonal) terms (m<20, n<=200) and high degree terms (n>200)
- Strictly inverse the normal matrix based on OpenMP
(2) Details of the GRACE processing procedures:
(2a) Input data:
-- GRACE L1B (JPL) data products: GNV1B RL02, ACC1B RL02, SCA1B RL03 and KBR1B RL03
-- AOD1B RL06 (GFZ) de-aliasing product
-- Data period: 04/2002-05/2017
(2b) Data preprocessing:
-- Splitting data of SCA1B into subsections for gaps > 120s and interpolation with polynomial for gaps <= 120s
-- Splitting data of ACC1B into subsections for gaps > 5s and interpolation with polynomial for gaps <= 5s
-- Gross outlier elimination ACC1B with a moving window of length 10 min, and interpolation with polynomial
-- Pre-calibration of ACC1B with a-priori bias and scale Parameters provided by GRACE TN-02
(2c) Calculation method:
- dynamic approach
- numerical integrator: 8th-order Gauss-Jackson integrator
- integrator step: 5 seconds
- arc length: 24 hours
(2d) Combination
- GNV1B and KBR1B are combined with their a-priori precision, i.e. 2cm of GNV1B and 2um/s of KBR1B
- The normal equations of different months are combined with variance components estimation
(2e) Force models:
- Earth's static gravity field: GGM05s up to d/o 180
- Solid earth tides: IERS 2010
- Ocean tides: FES2014b up to d/o 180
- Solid Earth pole tide: IERS 2010
- Ocean pole tide: Desai 2002 up to d/o 180
- N-body Perturbation: the Sun and Moon with JPL DE421
- atmospheric tides: Bode and Biancale model
- AOD1B product: AOD1B RL06 model up to d/o 180
- General Relativistic effects: Schwarzschild terms of IERS 2010