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, n200)   
        - 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  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