47 documents found in 334ms
# 1
Dobslaw, Henryk • Dill, Robert • Zhang, Liangjing • Boergens, Eva
Abstract: GRACE/GRACE-FO Level-3 product representing Ocean Bottom Pressure (OBP) variations provided at 1° latitude-longitude grids as defined over ocean areas. The OBP grids are provided in NetCDF format divided into yearly batches. The files each contain eight different variables: 1) 'barslv': gravity-based barystatic sea-level pressure2) 'error_barslv': gravity-based barystatic sea-level pressure uncertainties3) 'resobp': gravity-based residual ocean circulation pressure resobp4) 'error_resobp': gravity-based residual ocean circulation pressure uncertainties5) 'leakage': apparent gravity-based bottom pressure due to continental leakage leakage6) 'error_leakage': apparent gravity-based bottom pressure due to continental leakage uncertainties7) 'model_ocean': background-model ocean circulation pressure8) 'model_atmosphere': background-model atmospheric surface pressure These Level-3 products are visualized at GFZ's web portal GravIS (http://gravis.gfz-potsdam.de). Link to data products: ftp://isdcftp.gfz-potsdam.de/grace/GravIS/GFZ/Level-3/OBP
# 2
König, Rolf • Schreiner, Patrick • Dahle, Christoph
Abstract: As a convenience to users who wish to use a replacement value for C(2,0) of GFZ's GRACE/GRACE-FO RL06 GSM products, a monthly GFZ C(2,0) estimate time series is provided. These estimates are obtained from the analysis of Satellite Laser Ranging (SLR) data to the following five geodetic satellites: LAGEOS-1 and 2, Starlette, Stella and Ajisai. Starting from March 2012, the LARES satellite is added so that six geodetic satellites are included. The individual satellites are combined on normal equation level using relative weights which are based on a variance component estimation. Gravity field coefficients up to degree and order 5 plus coefficients C(6,1) and S(6,1) have been simultaneously solved together with all other (non-gravity) parameters. The background models used in the SLR analysis is consistent with the GFZ GRACE/GRACE-FO RL06 processing, including the use of the same Atmosphere-Ocean De-aliasing product AOD1B RL06. IMPORTANT REMARKS: It is advised to use these estimates to replace the C(2,0) values from the GFZ RL06 GSM files. These estimates are not intended to be used with the GRACE RL05 or earlier products. This data set is regularly updated in order to extend the time series on an operational basis. As long as the version number has not changed, all previously available data records have not been changed! See line 'UPDATE HISTORY' in the header of the data file for details about the current time span and version. SPECIAL NOTES: C(2,0) estimates are provided continuously for each month. However, the SLR data was processed in 7-day batches aligned to GPS weeks. Several weekly SLR normal equations were then accumulated to obtain a monthly solution; GPS weeks covering two calendar months were assigned to that calendar month where the majority of days within the week belong to. Thus, the beginning date for these 'monthly' solutions does not necessarily match the first day of a calendar month, but will be within a few days of that corresponding date. Moreover, in most cases, a different number of days was used for the SLR solution than for the corresponding GRACE/GRACE-FO solution. For particular periods, the GRACE/GRACE-FO solutions might span significantly less than one month or cover more than one calendar month. In these cases, a specially dedicated SLR estimate was generated which is based on approximately the same interval so that the epoch of the SLR estimate is close to the epoch of the GRACE/GRACE-FO solution. To distinguish the different cases of C(2,0) estimates mentioned above (monthly vs. specially dedicated) and to easily recognize whether a C(2,0) estimate matches an existing GRACE/GRACE-FO solution, the following flags are appended to each data record:- ' m': C(2,0) estimate represents a monthly solution for a month where no GRACE/ GRACE-FO solution is available.- 'Gm': C(2,0) estimate represents a monthly solution and a corresponding GRACE/ GRACE-FO solution is available.- 'G*': C(2,0) estimate is specially dedicated for a GRACE/GRACE-FO solution as described above; the effective period of data used is additionally provided by a string '<yymmdd>_<YYMMDD>'.
# 3
Dahle, Christoph • Murböck, Michael
Abstract: Post-processed GRACE/GRACE-FO spherical harmonic coefficients of GFZ RL06 Level-2 GSM products representing an estimate of Earth's gravity field variations during the specified timespan. Post-processing steps comprise: (1) subtraction of a long-term mean field; (2) optionally, decorrelation and smoothing with VDK filter (anisotropic filter taking the actual error covariance information of the underlying GSM coefficients into account, see Horvath et al. (2018)); (3) replacement of coefficient C20 and its uncertainty by values estimated from Satellite Laser Ranging (SLR); (4) subtraction of linear trend caused by Glacial Isostatic Adjustment (GIA) as provided by a numerical model; (5) insertion of coefficients of degree 1; and (6) removal of estimated signal with 161 days period. These coefficients represent signals caused by water mass redistribution over the continents and in the oceans. These post-processed GRACE/GRACE-FO GSM products are denoted as Level-2B products. There are multiple variants of Level-2B products available that differ by the characteristics of the anisotropic filter applied. These variants are distinguishable by the following strings in the product file names: - 'NFIL': Level-2B product is not filtered- 'VDK2': Level-2B product is filtered with VDK2- 'VDK3': Level-2B product is filtered with VDK3- 'VDK5': Level-2B product is filtered with VDK5 The individual data sets and models used during the post-processing steps mentioned above are provided as well (in the aux_data folder): - 'GRAVIS-2B_2002095-2016247_GFZOP_0600_NFIL_0001.gz': Long-term mean field calculated as unweighted average of the 156 available GFZ RL06 GSM products in the period from 2002/04 up to and including 2016/08.- 'GFZ_RL06_C20_SLR.dat': C20 time series from SLR (http://doi.org/10.5880/GFZ.GRAVIS_06_C20_SLR)- 'GRAVIS-2B_GIA_ICE5G_VILMA.gz': Model for subtraction of linear trend caused by GIA- 'GRAVIS-2B_DEG1_v01.dat': Degree-1 time series Detailed information about the product is provided in the header of the data file.
# 4
Dahle, Christoph • Flechtner, Frank • Murböck, Michael • Michalak, Grzegorz • Neumayer, Hans • (et. al.)
Abstract: Spherical harmonic coefficients representing an estimate of Earth's mean gravity field during the specified timespan derived from GRACE mission measurements. These coefficients represent the full magnitude of land hydrology, ice, and solid Earth processes. Further, they represent atmospheric and oceanic processes not captured in the accompanying GAC product.
# 5
Rudenko, Sergei • Schöne, Tilo • Esselborn, Saskia • Neumayer, Karl Hans
Abstract: The data set provides GFZ VER13 orbits of altimetry satellites: ERS-1 (August 1, 1991 - July 5, 1996),ERS-2 (May 13, 1995 - February 27, 2006),Envisat (April 12, 2002 - April 8, 2012),TOPEX/Poseidon (September 23, 1992 - October 8, 2005),Jason-1 (January 13, 2002 - July 5, 2013) andJason-2 (July 5, 2008 - April 5, 2015) derived at the time spans given at the GFZ German Research Centre for Geosciences (Potsdam, Germany) within the Sea Level phase 2 project of the European Space Agency (ESA) Climate Change Initiative using "Earth Parameter and Orbit System - Orbit Computation (EPOS-OC)" software (Zhu et al., 2004) and the Altimeter Database and processing System (ADS, http://adsc.gfz-potsdam.de/ads/) developed at GFZ. The orbits were computed in the ITRF2014 terrestrial reference frame for all satellites using common, most precise models and standards available and described below. The ERS-1 orbit is computed using satellite laser ranging (SLR) and altimeter crossover data, while the ERS-2 orbit is derived using additionally Precise Range And Range-rate Equipment (PRARE) measurements. The Envisat, TOPEX/Poseidon, Jason-1, and Jason-2 orbits are based on Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) and SLR observations. For Envisat, altimeter crossover data were used additionally at 44 of 764 orbital arcs with gaps in SLR and DORIS data. The orbit files are available in the Extended Standard Product 3 Orbit Format (SP3-c). Files are gzip-compressed. File names are given as sate_YYYYMMDD_SP3C.gz, where "sate" is the abbreviation (ENVI, ERS1, ERS2, JAS1, JAS2, TOPX) of the satellite name, YYYY stands for 4-digit year, MM for month and DD for day of the beginning of the file. More details on these orbits are provided in Rudenko et al. (2018) to which these orbits are supplementary material.
# 6
Mikolaj, Michal • Reich, Marvin • Güntner , Andreas
Abstract: This publication contains the supplementary data set to Mikolaj et al. "Resolving geophysical signals by terrestrial gravimetry: a time domain assessment of the correction-induced uncertainty" (2019, JGR-Solid Earth). The aim of the article is to estimate the uncertainty of terrestrial gravity corrections applied to resolve small-scale gravity effects. The uncertainty of the gravity corrections is assessed using various models of the tidal effect, large-scale hydrology, non-tidal ocean loading, and atmosphere. Taken into account are widely recognized models with global spatial coverage, sufficient temporal resolution and coverage, and available to the public for research purposes. The uncertainty is expressed in terms of a root-mean-square and mean-absolute error of the deviations between all available models. The data set comprises models for 11 sites worldwide. The processing scripts are provided along with an explanatory file with all instructions for results reproduction and application of the uncertainty analysis for an arbitrary location. Please consult the readme file for further details on the data.
# 7
Lu, Biao • Förste, Christoph • Barthelmes, Franz • Petrovic, Svetozar • Flechtner, Frank • (et. al.)
Abstract: With the successful completion of ESA's PolarGAP campaign, terrestrial gravimetry data (gravity anomalies) are now available for both polar regions. Therefore, it is now possible to overcome the GOCE polar gap by using real gravimetry data instead of some regularization methods. But terrestrial gravimetry data needs to become filtered to remove the high-frequency gravity information beyond spher. harm. degree e.g. 240 to avoid disturbing spectral leakage in the satellite-only gravity field models. For the gravity anomalies from the Arctic, we use existing global gravity field models (e.g., EGM2008) for this filtering. But for the gravity anomalies from Antarctica, we use local gravity field models based on a point mass modeling method to remove the high-frequency gravity information. After that, the boundary-value condition from Molodensky's theory is used to build the observation equations for the gravity anomalies. Finally, variance component estimation is applied to combine the normal equations from the gravity anomalies, from the GOCE GGs (e.g., IGGT_R1), from GRACE (e.g., ITSG-Grace2014s) and for Kaula's rule of thumb (higher degree/order parts) to build a global gravity field model IGGT_R1C without disturbing impact of the GOCE polar gap. This new model has been developed by German Research Centre for Geosciences (GFZ), Technical University of Berlin (TUB), Wuhan University (WHU) and Huazhong University of Science and Technology (HUST). Parametersstatic model modelname IGGT_R1Cproduct_type gravity_fieldearth_gravity_constant 0.3986004415E+15radius 0.6378136460E+07max_degree 240norm fully_normalizedtide_system tide_freeerrors formal
# 8
Rudenko, Sergei • Schöne, Tilo • Neumayer, Karl-Hans • Esselborn, Saskia • Raimondo, Jean-Claude • (et. al.)
Abstract: The data set provides GFZ VER11 orbits of altimetry satellites ERS-1 (August 1, 1991 - July 5, 1996),ERS-2 (May 13, 1995 - February 27, 2006),Envisat (April 12, 2002 - April 8, 2012),Jason-1 (January 13, 2002 - July 5, 2013) andJason-2 (July 5, 2008 - April 5, 2015)TOPEX/Poseidon (September 23, 1992 - October 8, 2005), derived at the time spans given at Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences within the Sea Level phase 2 project of the European Space Agency (ESA) Climate Change Initiative using "Earth Parameter and Orbit System - Orbit Computation (EPOS-OC)" software and the Altimeter Database and processing System (ADS, http://adsc.gfz-potsdam.de/ads/) developed at GFZ. The orbits were computed in the same (ITRF2008) terrestrial reference frame for all satellites using common, most precise models and standards available and described below. The ERS-1 orbit is computed using satellite laser ranging (SLR) and altimeter crossover data, while the ERS-2 orbit is derived using additionally Precise Range And Range-rate Equipment (PRARE) measurements. The Envisat, TOPEX/Poseidon, Jason-1 and Jason-2 orbits are based on Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) and SLR observations. The orbit files are available in the Extended Standard Product 3 Orbit Format (SP3-c, ftp://igscb.jpl.nasa.gov/igscb/data/format/sp3c.txt) Files are gzip-compressed. File names are given as sate_YYYYMMDD_SP3C.gz, where "sate" is the abbreviation (ENVI, ERS1, ERS2, JAS1, JAS2, TOPX) of the satellite name, YYYY stands for 4-digit year, MM stands for month and DD stands for day of the beginning of the file. More details on these orbits are provided in Rudenko et al. (2017)
# 9
Lu, Biao • Luo, Zhicai • Zhong, Bo • Zhou, Hao • Förste, Christoph • (et. al.)
Abstract: 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).
# 10
Förste, Christoph • Bruinsma, Sean • Abrikosov, Oleh • Rudenko, Sergiy • Lemoine, Jean-Michel • (et. al.)
Abstract: EIGEN-6S4 (Version 2) is a satellite-only global gravity field model from the combination of LAGEOS, GRACE and GOCE data. All spherical harmonic coefficients up to degree/order 80 are time variable. Their time variable parameters consist of drifts as well as annual and semi-annual variations per year. The time series of the time variable spherical harmonic coefficients are based on the LAGEOS-1/2 solution (1985 to 2003) and the GRACE-LAGEOS monthly gravity fields RL03-v2 (August 2002 to July 2014) from GRGS/Toulouse (Bruinsma et al. 2009). The herein included GRACE/LAGEOS data were combined with all GOCE data which have been processed via the direct numerical approach (Pail et al. 2011). The polar gap instabilty has been overcome using the Sperical Cap Regularization (Metzler and Pail 2005). That means this model is a combination of LAGEOS/GACE with GO_CONS_GCF_2_DIR_R5 (Bruinsma et al. 2013). Version History: This data set is an updated version of Foerste et al. (2016, http://doi.org/10.5880/icgem.2016.004) Compared to the first version, EIGEN-6S4v2 contains an improved modelling of the time variable part, in particular for C20.
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