HUST-Grace2016 is a new time series of monthly gravity field models up to degree and order 60. The new HUST-Grace2016s is a new GRACE-only static gravity field model up to degree and order 160. Using about 13 years of GRACE Level 1B data spanning from January 2003 to April 2015. This new model has been developed by the institute of geophysics in the Huazhong University of Science and Technology (HUST). No constraint was applied. More details about our HUST-Grace2016s will be given in our paper “HUST-Grace2016s: a new GRACE static gravity field model derived from a modified dynamic approach over a 13-year observation period” (submitted to JGR Solid Earth in November 2016).This work is supported by the National Natural Science Foundation of China (No. 41131067, 41374023, 41474019), the Project funded by China Postdoctoral Science Foundation (No. 2016M592337).
HUST-Grace2016s is a new GRACE-only static gravity field model up to degree and order 160. Using about 13 years of GRACE Level 1B data spanning from January 2003 to April 2015. This new model has been developed by the institute of geophysics in the Huazhong University of Science and Technology (HUST). No constraint was applied. More details about our HUST-Grace2016s will be given in our paper “HUST-Grace2016s: a new GRACE static gravity field model derived from a modified dynamic approach over a 13-year observation period” (submitted to JGR Solid Earth in November 2016).This work is supported by the National Natural Science Foundation of China (No. 41131067, 41374023, 41474019), the Project funded by China Postdoctoral Science Foundation (No. 2016M592337).
The WHU_RL01 GRACE monthly gravity field solutions are produced with the classical dynamic approach at the GNSS Research Center of Wuhan University. Three sets of monthly solutions complete to d/o 60, 90 and 120 are produced without any regularization for the time period from 2002-04 to 2016-07. K-Band range rates with a sampling of 5 seconds and reduced-dynamic orbits with a sampling of 5 minutes are used as observations. To account for the colored noise in the K-Band range-rate measurements, the frequency-dependent data weighting scheme proposed by Ditmar et al. (2007) is adopted. Additionally, a unified weight for the reduced-dynamic orbits is applied based on its a priori precision of 2 cm for each component. The strategy adopted for producing the WHU_RL01 GRACE monthly gravity field models is summarized in Table 1 (please find it in the attached explanatory file). It should be noted that relatively short arcs (6 hours per arc) are used to reduce the resonance effects caused by inaccuracies in initial state vectors and background force models (Colombo, 1984). The reduced-dynamic orbits are also used as observations in our data processing. Although a reduced-dynamic orbit contain certain a priori gravity field information, the resulting bias in the gravity field solutions have been proved to be limited when inverted together with the K-band measurements (Chen et al., 2014; Liu et al., 2010).
ITU_GRACE16 is a static global gravity field model up to degree order 180 computed from GRACE SST data of 50 months collected between April 2009 to October 2013 by collaboration of various national institutions (YTU, KOU, NEU, SU) lead by ITU and OSU as the international collaborator with the support of research grant no 113Y155 from the Scientific and Technological Research council of Turkey (TUBITAK). The model coefficients are obtained following a two-step approach. (1) the in-situ geopotential differences (GPDs) between GRACE satellite are estimated using SST and precise orbit using improved energy integral method given in Guo et al. 2015 and Shang et al. 2015. (2) The estimated GPDs were then used as the observables of the SH expansion for the inversion.ITU_GRACE16 is not regularized or constrained in any way, the errors increase with degree. We do not recommend to use ITU_GRACE16 beyond the degree 130 without smoothing. No rate terms were modeled, and no corrections for earthquakes have been applied. For additional details on the background modeling,see the GFZ RL05 processing standards document available at:
GOSG02S is a static gravity field model complete to spherical harmonic degree and order of 300 derived by using the Satellite Gravity Gradiometry (SGG) data and the Satellite-to-Satellite Tracking (SST) observations along the GOCE orbit based on least-squares analysis. 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, ... -- GOSG02S is a GOCE only satellite gravity model, since no priori gravity information was used in modelling procedure. 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
SGG-UGM-1 is a static gravity field model based on EGM2008 derived gravity anomalies and GOCE Satellite Gravity Gradiometry (SGG) data and the Satellite-to-Satellite Tracking (SST) observations up to degree and order 2159. Block-diagonal normal equation system up to degree and order 2159 are formed with EGM2008 gravity anomaly data using block-diagonal least squares method. Fully occupied normal equation system up to degree and order 220 are formed by GOCE SGG data and the SST observations along the GOCE orbit based on least-squares analysis. The diagonal components (Vxx, Vyy, Vzz) of the gravitational gradient tensor are used to form the system of observation equations with the band-pass ARMA filter. The point-wise acceleration observations (ax, ay, az) along the orbit are used to form the system of observation equations up to the maximum spherical harmonic degree/order 130. SGG-UGM-1 is resolved by combination of the two normal equation systems using least squares method. It is the first generation of high-resolution gravity model in ICGEM developed by School of Geodesy and Geomatics (SGG), Wuhan University (WHU). More details about the determination of the model are given in our paper “The determination of an ultra high gravity field model SGG-UGM-1 by combining EGM2008 gravity anomaly and GOCE observation data” (Liang W, Xu X, Li J, et al. Acta Geodaeticaet Cartographica Sinica. 2018, 47(4): 425-434. DOI:10.11947/j. AGCS.2018.20170269) and “A GOCE only gravity model GOSG01S and the validation of GOCE related satellite gravity models ” (Xu X, Zhao Y, Reubelt T, et al. Geodesy and Geodynamics. 2017, 8(4): 260-272. http://dx.doi.org/10.1016/j.geog.2017.03.013). The work is supported by the Natural Science Foundation of China (Nos. 41774020, 41210006 and 41404020
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
IGGT_R1 is a static gravity field model based on the second invariant of the GOCE gravitational gradient tensor, up to degree and order 240. Based on tensor theory, three invariants of the gravitational gradient tensor (IGGT) are independent of the gradiometer reference frame (GRF). Compared to traditional methods for calculation of gravity field models based on GOCE data, which are affected by errors in the attitude indicator, using IGGT and least squares method avoids the problem of inaccurate rotation matrices. IGGT_R1 is the first experiment to use this method to build a real gravity field model by using GOCE gravitational gradients.This new model has been developed by Wuhan University (WHU), GFZ German Research Centre for Geosciences (GFZ), Technical University of Berlin (TUB), Huazhong University of Science and Technology (HUST) and Zhengzhou Information Engineering University (IEU). More details about the gravity field model IGGT_R1 is given in our paper “The gravity field model IGGT_R1 based on the second invariant of the GOCE gravitational gradient tensor” (Lu et al., 2017, http://doi.org/10.1007/s00190-017-1089-8).This work is supported by the Chinese Scholarship Council (No. 201506270158), the Natural Science Foundation of China (Nos. 41104014, 41131067, 41374023, 41474019 and 41504013) and the Key Laboratory of Geospace Environment and Geodesy, Ministry Education, Wuhan University (No. 16-02-07).
This data publication presents the anonymized original answers of the ICGEM user survey “Analysis and Future Plans with the SAMDAT Project”. In total, 112 respondents completed the survey. Data collection started on the 1st of September and ended on the 31st of October 2024. The survey was announced on the ICGEM website, and the questionnaire was integrated directly into the website. A separate page was developed explaining the survey purpose. Respondents were contacted via the ICGEM users mailing list, the geodesy mailing list, and LinkedIn. Responses were collected anonymously from the beginning. The objective of the survey is twofold: firstly, to ascertain the current user experience with the portal and, secondly, to identify potential areas for improvement of the service. The analysis identifies various user groups in order to find out how ICGEM can best serve the needs of a diverse range of geoscientific applications. It is crucial to comprehend user expectations, since ICGEM is dedicated to demand-driven development. Furthermore, the survey offers users the chance to indicate their priorities for planned features and extensions of the ICGEM platform within the SAMDAT project. The associated report (Torhov et al., 2025) presents the analyses of user feedback gathered from the global user community of the ICGEM Service (International Centre for Global Earth Models). ICGEM serves as a pivotal resource for gravity field modelling, serves as primary resource for global gravitational models and offers an array of interactive tools. Through the recently launched SAMDAT project, ICGEM continues to improve it service and web presentation. New gravity field functionals, datasets and improved metadata are planned to be introduced in alignment with community needs. This user survey was an important first step to collect feedback on the current and upcoming service portfolio of ICGEM. Survey data was collected through a questionnaire to assess scientific applications, uncover feature expectations, and identify opportunities for improvement. The results confirm ongoing project activities and set new directions such as in data representation, documentation and outreach.
The joint ESA/NASA Mass-change And Geosciences International Constellation (MAGIC) mission has the objective to extend time series from previous gravity missions, including an improvement of accuracy and spatio-temporal resolution. The long-term monitoring of Earth's gravity field carries information on mass-change induced by water cycle, climate change, and mass transport processes between atmosphere, cryosphere, oceans and solid Earth. The MAGIC mission will be composed of two satellite pairs flying in different orbit planes. The NASA/DLR--led first pair (P1) is expected to be in a near-polar orbit around 500 km of altitude; while the second ESA--led pair (P2) is expected to be in an inclined orbit of 65--70 degrees at approximately 400 km altitude. The ESA--led pair P2 Next Generation Gravity Mission (NGGM) shall be launched after P1 in a staggered manner to form the MAGIC constellation. The addition of an inclined pair shall lead to reduction of temporal aliasing effects and consequently of reliance on de-aliasing models and post-processing. The main novelty of the MAGIC constellation is the delivery of mass-change products at higher spatial resolution, temporal (i.e. sub--weekly) resolution, shorter latency, and higher accuracy than GRACE and GRACE-FO. This will pave the way to new science applications and operational services. The performances of different MAGIC mission scenarios for different application areas in the field of geosciences were analysed in the frame of the initial ESA Science Support activities for MAGIC. The data sets provided here are the Level-2a simulated gravity field solutions of MAGIC scenarios and the related reference signal that were used for these analyses. The .gfc files in the folders monthly (31-day solutions) and weekly (7-day solutions) contain the estimated (HIS) coefficients (Cnm, Snm) as well as the formal errors (SigCnm, SigSnm) of the different MAGIC scenarios. In order to compute the coefficient errors, the reference/true HIS coefficients contained in the folder HIS_reference_fields need to be subtracted from the estimated HIS coefficients. The data sets provided here comprise the Level-2a simulated gravity field solutions of MAGIC scenarios and the related reference signal (based on Dobslaw et al. 2014; 2015) that were used for the above analyses.
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