11 documents found in 310ms
# 1
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)
# 2
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.
# 3
Mayer-Gürr, Torsten • Behzadpour, Saniya • Ellmer, Matthias • Kvas, Andreas • Klinger, Beate • (et. al.)
Abstract: The ITSG-Grace2016 gravity field model is the latest GRACE only gravity field model computed at Graz University of Technology, providing unconstrained monthly and Kalman smoothed daily solutions. It covers the whole GRACE time span from 2002-04 and will be continually updated. For each month of the observation period, sets of spherical harmonic coefficients for different maximum degrees (60, 90, 120) were estimated without applying any regularization. In order to resolve daily gravity field variations as detailed as possible, a set of spherical harmonic coefficients up to degree and order 40 was estimated using the Kalman smoother estimation procedure introduced by Kurtenbach et al. 2012.K-band range rates with a sampling of 5 seconds and kinematic orbits with a sampling of 5 minutes were used as observations. The kinematic orbits of the GRACE satellites (Zehentner and Mayer-Gürr 2013, 2014) were processed using the GPS orbits and clock solutions provided by IGS. An improved attitude product derived from a combination of star camera data and angular accelerations (Klinger and Mayer-Gürr 2014) was used to estimate K-band antenna center variations (one set per month). Additionally, accelerometer scale factors were estimated per axis and day. The accelerometer bias was modelled through cubic splines with a node interval of six hours and estimated for each axis and day. Detailed information about ITSG-Grace2016 is available at http://ifg.tugraz.at/ITSG-Grace2016.
# 4
Ries, J. • Bettadpur, S. • Eanes, R. • Kang, Z. • Ko, U. • (et. al.)
Abstract: GGM05C is an unconstrained global gravity model complete to degree and order 360 determined from 1) GRACE K-band intersatellite range-rate data, GPS tracking and GRACE accelerometer data, 2) GOCE gradiometer data (ZZ+YY+XX+XZ) spanning the entire mission using a band pass filter of 10-50 mHz and polar gap filled with synthetic gradients from GGM05S to degree/order 150 evaluated at 200-km altitude, and 3) terrestrial gravity anomalies from DTU13 (Andersen et al., 2014). The value for C20 has been replaced with a value derived from satellite laser ranging. No rate terms were modeled. For additional details on the background modeling, see the CSR RL05 processing standards document available at ftp://podaac.jpl.nasa.gov/allData/grace/docs/L2-CSR0005_ProcStd_v4.0.pdf (Bettadpur 2012). Detailed information about GGM05C is available at ftp://ftp.csr.utexas.edu/pub/grace/GGM05/README_GGM05C.pdf (Ries et al., 2016).
# 5
Förste, Christoph • Voigt, Christian • Abe, Maiko • Kroner, Corinna • Neumeyer, Jürgen • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy IAG. IGETS continues the activities of the Global Geodynamics Project (GGP) between 1997 and 2015 to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. As part of this network, the South African Geodynamic Observatory Sutherland (SAGOS) was established by the GFZ German Research Centre for Geosciences during the years 1998 and 2000 based on an Agreement on Cooperative Activities between the National Research Foundation (NRF) and GFZ signed in August 1998. Continuous time-varying gravity and atmospheric pressure data from the SGs at SAGOS are integrated in the IGETS data base hosted by GFZ. The SAGOS observatory is located at the site of the South African Astronomical Observatory (SAAO) approximately 350 km northeast of Cape Town (longitude: 20.81 E, latitude: 32.38 S, height above MSL: 1755 m). The operation and maintenance of the SAGOS instrumentation is jointly done by staff of SAAO and GFZ. The shortest distance to the South Atlantic coastline is approximately 200 km. The area is located in a tectonically quiet zone far away from the African rift. Geologically, the setting is a huge dolerite plateau with a several kilometres thick layer of dolerite. This bedrock allows a good coupling of the SG pillars to the ground. The environment is a remote area with no industry and low seismicity. The climate at this place is determined by the border between summer and winter rainfall zones so that temperature fluctuations are not too rough. The observatory is built into the ground to protect it against environmental effects like strong winds and temperature changes. All rooms are thermally insulated. An air-conditioning system controls the temperature inside the measurement chamber, which is equipped with three concrete pillars embedded into the dolerite bedrock. Two of the pillars are constructed for SGs or other geophysical instruments. The third pillar is dedicated for absolute gravimeters for the calibration of the SGs. In the vicinity of the observatory four further pillars were set up for various other geodetic antennas and instrumentation.SAGOS is a high precision geodynamic observatory comprising space techniques and ground instruments. Presently, the observatory is equipped with two SGs manufactured by GWR Instruments (SG D037 and SG 052). The time series of gravity and barometric pressure from the dual sensor gravimeter SG D037 starts in February 2000 and is interrupted from July 2008 to November 2009 due to an upgrade of the electronics package. The time series of SG 052 begins in August 2008 without interruption. Both SGs are active and the time series are kept up to date regularly with a time delay of a few months. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 minute. Starting in January 2016, raw data with a time sampling of 1 second is provided additionally. For a detailed description of the IGETS data base and the provided files see Voigt et al. (2016, http://doi.org/10.2312/GFZ.b103-16087). In addition, SAGOS is equipped with auxiliary data supporting the interpretation of the SG measurements, which is, however, not provided in the IGETS data base due to their complexity. These are a local network of hydrological and meteorological sensors as well as a permanent GNSS (Global Navigation Satellite Systems) station as a core station of the International GNSS Service (IGS) with the ID SUTM.
# 6
Akyilmaz, O. • Ustun, A. • Aydin, C. • Arslan, N. • Doganalp, S. • (et. al.)
Abstract: ITU_GGC16 is a static global gravity field model up to degree order 280 computed from the combination of ITU_GRACE16 (up to d/o 180) and GO_CONS_GCF_2_TIM_R5 (up to d/o 280) 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 combination is performed at the normal equation level with variance component estimation. 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 by Dahle et al. (2012).
Input Data:- ITU_GRACE16: Normal Equations (full)- GO_CONS_GCF_2_TIM_R5: Normal Equations (full)- GIF48 static field as the background gravity field model (only up to d/o 180)
# 7
Zhou, H. • Luo, Z • Zhou, Z. • Zhong, B. • Hsu, H.
Abstract: 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).
Input Data:- GRACE RL02 L1B (JPL) data products: January 2003 – March 2016- ITSG kinematic orbits: January 2003 – April 2015- AOD1B RL05 (GFZ) idealizing product Calculation method:- modified dynamic approach- numerical integrator: 14th-order Gauss-Jackson integrator- arc length: 24 hours- arc step: 5 seconds Force models:- Earth’s static gravity field: GGM05s up to degree and order 180- Ocean tides: EOT11a, truncated up to degree and order 120- N-body Perturbation: Direct and indirect J2 effects with JPL DE421- Solid earth tides: frequency independent/dependent terms, permanent tide- Solid earth tides: frequency independent/dependent terms, permanent tide- Pole tides: solid earth pole tides from IERS 2010, and ocean pole tides from Desai- Atmosphere and Oceanic variability: The AOD1B RL05 model up to degree 100- General Relativistic effects: IERS 2010
# 8
Akyilmaz, O. • Ustun, A. • Aydin, C. • Arslan, N. • Doganalp, S. • (et. al.)
Abstract: 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:
Input Data:- GRACE RL02 L1B (JPL) data products: 50 months Apr 2009 – Oct 2013- AOD1B RL05 (GFZ) idealising product- GIF48 static field as the background gravity field model (only up to d/o 180)
# 9
Pail, Roland • Gruber, Thomas • Fecher, Thomas • GOCO Project Team
Abstract: GOCO05c is a static global combined gravity field model up to d/o 720. It has been elaborated by the GOCO Group (TU Munich, Bonn University, TU Graz, Austrian Academy of Sciences, University Bern). GOCO05c is a combination model based on the satellite-only gravity field model GOCO05s and several gravity anomaly datasets, constituting a global 15'x15' data grid. The combination is carried out in term of full normal equation systems.Contributing Institutions are: (1) TU Muenchen, DE, Institute of Astronomical and Physical Geodesy; (2) University of Bonn, DE, Institute of Geodesy and Geoinformation; (3) TU Graz, AU, Institute of Theoretical and Satellite Geodesy; (4) Austrian Academy of Sciences, Space Research Institute, and (5) University of Bern, CH, Astronomical Institute
Global 15’x15’ data grid: Region (Source): Number of data cellsArctic (ArcGP Group): 44522Australia (Curtin University):11170Canada (NRCan):19259Europe (IfE Hanover):15625Oceans (DTU Space): 691818South America (NGA): 24818USA (NGA): 12895 For the remaining land areas (Central America, Asia, Africa, Antarctica) fill-in datasets were used: Data (Source): Number of data cells NIMA96 (DMA/GSFC): 110594GOCO05s (GOCO Group): 106099 (band-limited gravity anomalies)RWI_TOIS2012 (KIT): 117737 (topographic anomalies) GOCO05c should not be used for geophysical applications in fill-in regions, because its high frequency part in fill-in regions resulted from simple synthetic numeric forward modelling of topographic information.
# 10
Zhou, H. • Luo, Z • Zhou, Z. • Li, Q. • Zhong, B. • (et. al.)
Abstract: 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).
Input Data:- GRACE RL02 L1B (JPL) data products: January 2003 – March 2016- ITSG kinematic orbits: January 2003 – April 2015- AOD1B RL05 (GFZ) idealizing product Calculation method:- modified dynamic approach- numerical integrator: 14th-order Gauss-Jackson integrator- arc length: 24 hours- arc step: 5 seconds Force models:- Earth’s static gravity field: GGM05s up to degree and order 180- Ocean tides: EOT11a, truncated up to degree and order 120- N-body Perturbation: Direct and indirect J2 effects with JPL DE421- Solid earth tides: frequency independent/dependent terms, permanent tide- Solid earth tides: frequency independent/dependent terms, permanent tide- Pole tides: solid earth pole tides from IERS 2010, and ocean pole tides from Desai- Atmosphere and Oceanic variability: The AOD1B RL05 model up to degree 100- General Relativistic effects: IERS 2010
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