17 documents found in 312ms
# 1
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).
# 2
Wziontek, Hartmut • Wolf, Peter • Häfner, Michael • Hase, Hayo • Nowak, Ilona • (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, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. In April 2015 the Transportable Integrated Geodetic Observatory (TIGO) was moved from Concepción/Chile to La Plata/Argentina (longitude: 58.14 W, latitude: 34.87 S, height above MSL: 25 m) and is jointly operated by the Federal Agency for Cartography and Geodesy (BKG) and the Argentinian National Scientific and Technical Research Council (CONICET) as Argentinian-German Geodetic Observatory (AGGO). The superconducting gravimeter SG038 was transported 3100 km overland by truck with the sphere floating. AGGO is located near the Rio de la Plata, formed by the confluence of the Paraná and Uruguay rivers and is one of the world’s largest estuaries. Since December 2015, an almost uninterrupted time series of gravity and barometric pressure variations is acquired with SG038. The gravity laboratory is a solid building and equipped with four stable pillars of concrete in one room, founded 5 meters deep. One pillar is used for the SG while the others are available for absolute gravimeters. The site will thus serve as a reference station and comparison site for absolute gravimeters. The site is thermally stabilized by air-conditioning systems. To assess the gravity effects caused by local water storage variations in the groundwater and vadose zone, a hydrological monitoring network was set up in close cooperation with GFZ Potsdam near to the gravimeter building, consisting of a weather station (precipitation, air temperature, air humidity, wind speed, wind direction, solar radiation, net radiation), soil moisture sensors, vertical soil moisture profiles to record water storage changes close to the gravimeter and two groundwater observation wells.
# 3
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (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, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The gravimetric reference station Bad Homburg (Germany) is operated by the Federal Agency for Cartography and Geodesy (BKG) and was established in 1979. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The district town Bad Homburg is situated about 25 km north-east of Frankfurt/Main (longitude: 8.61 E, latitude: 50.23 N, height above MSL: 188 m) on the southern slope of the Taunus mountains. The gravity station is located inside a cellar of the Landgraves' Castle and is characterized by low environmental noise. Inside the vault a separated housing with insulated walls enables controlled environment. All rooms are thermally stabilized by an air-conditioning system. The station provides 5 separate piers of concrete (2 for SG, 3 for AG) which are grounded on bedrock (approx. 1.8 m deep, on greenschist) and are decoupled from the wooden floor. Since 1981, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started. From December 1999 to April 2007 the dual sphere SG CD030 was operated and since February 2007 OSG044 is recording. These data are available at the IGETS database. The first SG installed at the station was TT40 (1981/04-1989/06, later at Richmond/Florida, USA) and TT60 (1985/06-1988/11, later at Wettzell/Germany). Several shorter test registrations were performed with SG103 (1998/12-1999/04), as well as SG030 (2008/02-2010/06) and SG029 (2011/03-2012/04) after upgrades. In November 2003 and May 2004 two ground water wells within a distance of 200 m were constructed to support the monitoring of local water storage changes. Due to the excellent stability of the station and the ability of facilities to inter-compare absolute and superconducting gravimeters, the station Bad Homburg was developed as a reference site for the national German gravity reference system. In Addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017, http://doi.org/10.5880/igets.we.gfz.l1.001).
# 4
Wziontek, Hartmut • Wolf, Peter • Böer, Armin • Hase, Hayo • Nowak, Ilona • (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, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Transportable Integrated Geodetic Observatory (TIGO) of the Federal Agency for Cartography and Geodesy (BKG) was operated with different local partners (Universidad de Concepción, Universidad del Bío-Bío, Universidad Católica de la Santísima and Instituto Geografico Militar) from 2002 until 2015 at Concepción/Chile. Continuous temporal gravity and atmospheric pressure time series from the SG is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The TIGO Observatory was located near Concepción, Chile (longitude: 73.03 W, latitude: 36.84 S, height above MSL: 180 m) in a hilly region based on weathered granite close to the estuary of the Rio Bío-Bío. One component of the observatory was RSG-038, the first remote controlled SG. The SG was operated in a separate building containing one room with 3 pillars of concrete (SG, AG and Seismic). The building was thermally stabilized by air-conditioning system. The first period of operation of the SG was from December 2002 until June 2008. For a complete update of the cooling system the SG was sent back to the manufacturer. It was reinstalled in December 2009 and recorded until April 2015 gravity and barometric pressure variations. From June 2006 until May 2013, periodic (almost weekly) measurements with the absolute gravimeter (AG) FG5-227 were performed, except for a maintenance period from October 2007 to October 2008. The devastating Mw 8.8 Maule earthquake of February 27th 2010 affected also the registration. Re-centering of the sphere and repair of the tilt compensation system was necessary. For more than one year the gravity time series was disturbed by countless seismic aftershocks, causing spikes and steps in the registration. At the station, a meteorological (precipitation, air temperature, humidity, wind speed) and hydrological (soil moisture, since January 2006, ground water since April 2012) monitoring system is installed and operated in close cooperation with GFZ Potsdam.
# 5
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (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, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The gravimetric station Medicina/Italy operated by the Federal Agency for Cartography and Geodesy (BKG), Germany, and the Department of Physics and Astronomy (DIFA) at the University of Bologna, Italy, was established in 1996. Continuous temporal gravity and atmospheric pressure time series from the SG is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The gravimetric station is located at the premises of the Medicina Radio Observatory (Northern Cross) of Istituto Nazionale di Astrofisica (INAF), 30 km south-east from Bologna in the southeastern Po Plain. The plain runs parallel to the Pede–Apenninic border and represents a sediment-filled foredeep, where a huge sedimentary deposition (more than 5000 m of thickness) occurred during the Plio-Pleistocene. The uppermost stratigraphic sequences in the Plain are made of alternating sands, silts and clays variably interbedded and normally consolidated. Since 1996, an almost uninterrupted time series of gravity and barometric pressure variations are acquired with SG C-023. In the same year a series of repeated absolute gravity measurements with different AGs started. Although the gravity building is not well thermally isolated, the air-conditioning system compensates main temperature variations, keeping the room temperature stable within a range of 5 K. The hut facilitates three pillars of concrete in one room, one used for the SG and two for absolute gravimeters. All pillars show a slight seasonal tilting due to soil consolidation. This effect is mostly compensated by tilt compensation system of the SG. Since June 1995 and November 2004, data from two ground water wells, one in a distance of 500 m, the other nearby, are recorded, supporting the monitoring of local water storage changes.
# 6
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (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, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Geodetic Observatory Wettzell (Germany) is operated jointly by the Federal Agency for Cartography and Geodesy (BKG) and the Technical University of Munich (TUM) and was established in 1972. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The Geodetic Observatory Wettzel is located on a mountain ridge of the Bavarian Forest (longitude: 12.88 E, latitude: 49.10 N, height above MSL: 611 m). The crystalline basement of metamorphic rocks (Gneiss) in Wettzell is covered from bottom to top by weathering zones of fractured gneiss, saprolite, periglacial weathering layers and soil, with Cambisols making up the predominant soil type. The climate is temperate with mean annual precipitation of 995 mm and mean annual temperature of 7°C. Land cover in the surroundings of the observatory is dominated by a mosaic of grassland and forest, while grassland, gravel and sealed surfaces of roads and buildings alternateon the grounds of the observatory. Because of the remote, rural location the station is characterized by low environmental noise. Since 1989, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started. There are two gravity laboratories at station Wettzell: L1 and L2. L1 was built in 1988. It is an isolated solid building with 2 concrete pillars in separate rooms for SG and AG observations. Now each room is thermally stabilized by air-conditioning system. The new laboratory L2 is a well isolated solid building constructed in 2009. It provides 2 concrete pillars in separate rooms for SG observations and 4 concrete pillars for AG observations and comparisons in a third room. All rooms are thermally stabilized by air-conditioning systems. From November 1999 to October 2010 the dual sphere SG CD029 was operated in L1 and since June 2010 the dual sphere SG030 (after upgrade) is recording in L2. Since March 2011 the dual sphere SG029 (after upgrade) is recording data in L1 again. These data are available at the IGETS database. Earlier, TT60 (1989/09-1995/06) and SG103 (1996/04-1997/07) were installed at L1. Due to the excellent stability of the station and the facilities to inter-compare different AGs, the Geodetic Observatory Wettzell was developed as a regional comparison site which serves as a reference for the national German gravity reference system. At the area of the station, an extensive meteorological (precipitation, air temperature, humidity, wind speed and net radiation) and hydrological (ground water, soil moisture, including a weighing lysimeter) monitoring system is installed and operated in close cooperation with GFZ Potsdam. In addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017: http://doi.org/10.5880/igets.we.gfz.l1.001).
# 7
Boy, Jean-Paul • Rosat, Séverine • Hinderer, Jacques • Littel, Frédéric
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy. 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 Strasbourg station (code ST) was established in 1996 thanks to the financial support of INSU-CNRS France. Continuous time-varying gravity and atmospheric pressure data from ST are integrated in the IGETS data base hosted by ISDC (Information System and Data Centre) at GFZ. The ST station is the unique permanent station in France belonging to the geophysical observatories funded by INSU-CNRS. The operation and maintenance of the ST instrumentation is done by staff at EOST/IPG Strasbourg. The ST station is located in an old bunker built in 1875 (called J9) which is 10 km away from Strasbourg city (longitude: 7.684 E, latitude: 46.622 N, height above MSL: 180 m). The area is located in the sediments of the Rhine graben and the local environment is agricultural with no close industry. The observatory is partly underground with a loess layer of about 1 m thick above it. An air-circulation system controls the humidity and temperature in all the rooms inside the bunker and there are about 10 pillars available. One room is dedicated to the absolute gravity measurements done regularly with FG5#206 operated by EOST Strasbourg. SG C026 manufactured by GWR Instruments was installed in 1996 and still in operation on a several meter deep pillar in a separate room. The new SG iOSG#23 was installed in February 2016 in another room on a more superficial pillar. Both meters will run side by side for a couple of years in order to perform an intercomparison in terms of noise level and instrumental drift. The time series of gravity and barometric pressure from SG C026 starts in July 1996 and is still going on. The time series of gravity and barometric pressure from iOS#23 starts in February 2016. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 minute. Raw data with a time sampling of 1 second will be provided additionally on the seismological IRIS Data Management Center (http://ds.iris.edu/mda/SG/ST). 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, ST station is equipped with auxiliary data supporting the interpretation of the SG measurements, which is, however, not provided in the IGETS data base due to complexity. These are a local network of hydrological and meteorological sensors as well as a permanent GNSS (Global Navigation Satellite Systems) station belonging to the RENAG network (http://renag.resif.fr/).
# 8
Neumeyer, Jürgen • Dittfeld, Hans-Jürgen • Pflug, Hartmut • Voigt, Christian • Förste, Christoph
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 superconducting gravimeter TT70 No. 18 by GWR recorded gravity data at the Gravimetric Observatory Potsdam Telegrafenberg, northeast cellar of building A17 (Helmert House) site S12. Continuous time-varying gravity and barometric pressure data from the SG at GFZ are integrated in the IGETS data base hosted by GFZ. The time series of gravity and barometric pressure data starts in July 1992 and ends in August 1998. The SG was upgraded by GWR in 1999 replacing the gravity sensing unit by a dual sphere and was installed as SG D037 at Sutherland (Förste et al. 2016, http://doi.org/10.5880/igets.su.l1.001). 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).
# 9
Lu, Biao • Barthelmes, Franz • Petrovic, Svetozar • Pflug, Hartmut • Förste, Christoph • (et. al.)
Abstract: The dataset contains the results of airborne gravimetry realized by the GEOHALO flight mission over Italy in 2012. The intention was to show whether and how an efficient airborne gravity field determination is feasible in wide areas when using a fast jet aircraft like HALO at higher altitudes. Here, unlike in airborne gravimetry for exploration purposes, the aim is not primarily to reach the highest spatial resolution by flying as low and slowly as possible. A challenge for HALO would be to map areas (e.g., Antarctica) where only insufficient or no terrestrial gravity data are available to achieve a resolution which is better than that of satellite-only gravity field models. This is beneficial for the generation of global gravity field models which require a uniform, high spatial resolution for the gravity data over the entire Earth. The raw gravimetry recordings were recorded by the GFZ air-marine gravimeter Chekan-AM. Kinematic vertical accelerations were calculated from Doppler observations which were derived by GNSS carrier phase measurements (1 Hz). To remove the high-frequency noise, a low-pass filter with a cut-off wavelength of 200 s (corresponding to a half-wavelength resolution of approximately 12 km) was applied to both the Chekan-AM measurements and GNSS kinematic accelerations. To investigate how future airborne gravity campaigns using jet aircraft could be optimized, a dedicated flight track was repeated two times which shows that the equipment worked well also at higher altitude and speed. For the accuracy analysis 17 crossover points could be used. This analysis yielded a RMS of the gravity differences of 1.4 mGal which, according to the law of error propagation, implies an accuracy of a single measurement to be 1 mGal. The dataset is provided in as ASCII text (Lu-et-al_2017-001_Tracks_GEOHALO.txt) and is described in the README. For a detailed description of the set-up and analysis of the data, please see Biao et al. (2017, http://doi.org/10.1002/2017JB014425).
# 10
Wu, Hu • Müller, Jürgen • Brieden, Phillip
Abstract: IfE_GOCE05s is a GOCE-only global gravity field model, which was developed at the Institut für Erdmessung (IfE), Leibniz Universität Hannover, Germany. The observations with a time span from 1 November 2009 to 20 October 2013 are used for the model recovery. The GOCE precise kinematic orbit with 1-s sampling rate is processed for the gravity field up to degree/order 150, while the three main diagonal gravity gradients are down-sampled to 2 s and used to recover the model up to degree/order 250. With two additional Kaula’s regularizations, the combined model “IfE_GOCE05s” is derived, with a maximum degree of 250. To develop IfE_GOCE05s, the following GOCE data (01.11.2009 - 20.10.2013) was used: * Orbits: SST_PKI_2, SST_IAQ_2; * Gradients: EGG_GGT_2, EGG_IAQ_2. None any priori gravity field information was used.
Processing procedures: Gravity from orbits (SST): * Acceleration approach was applied to the kinematic orbit data; * PKI data was at 1 s sampling rate; * Model was derived up to d/o (degree/order) 150; * VCM (Variance-Covariance Matrix) was derived arc-wisely from the post-fit residuals. Gravity from gradients (SGG): * Gradients Vxx, Vyy and Vzz in the GRF (Gradiometer Reference Frame) were used; * Gradients were down-sampled to 2 s; * Model was derived up to d/o 250; * VCM was estimated arc-wisely from the post-fit residuals. Regularization: * A strong Kaula-regularization was applied to constrain the (near-)zonal coefficients that are degraded by the polar gap problem; * A slight Kaula-regularization was applied to improve the signal-to-noise ratio of the coefficients between d/o 201 and 250; * The regularization parameters were empirically determined. Combined solution: * The normal equations for SST and SGG were summed wih proper weighting factors; * Weighting factors for SST and SGG were determined from variance component estimation; * A direct inversion was applied on the final normal equation.
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