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Superconducting Gravimeter Data from Buchholz, Eifel - Level 1

The International Geodynamics and Earth Tides 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 Eifel Gravimetric Observatory Germany (EIGOG) was established by the GFZ Helmholtz Centre for Geosciences in August 2025. Continuous time-varying gravity and atmospheric pressure data from the SG at EIGOG are integrated in the IGETS data base hosted by GFZ. The EIGOG observatory is located at the Buchholz Provostry (Propstei Buchholz) in the municipality of Burgbrohl. It is part of a multiparameter station for the monitoring and analysis of seismic and volcanic signals within the Central European Volcanic Province Observatory (CVO) in the Eifel region. Additional sensors at Buchholz are GNSS, InSAR corner reflector, seismometer, tiltmeter, groundwater level and a weather station. The operation and maintenance of the EIGOG instrumentation is done by staff of the GFZ. EIGOG is a high precision gravimetric observatory with the dual-sphere OSG D037 manufactured by GWR Instruments as core instrument, one of the two SGs operating at Sutherland, South Africa, until December 2024 (Förste et al., 2016, http://doi.org/10.5880/igets.su.l1.001). The time series of gravity and barometric pressure from the OSG D037 starts in August 2025. The SG is active and the time series is 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 second and 1 minute. 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).

Superconducting Gravimeter Data from Conrad Observatory - Level 1

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. The Conrad Observatory (CO) is located at Trafelberg, Lower Austria, about 50 km south-west of Vienna at an elevation of about 1050m. Three different geological formations are found in the vicinity of the CO: the Gutenstein Formation, Reifling Formation, and Wetterstein Limestone. The observatory is part of a large underground installation covering the full geophysical monitoring program including seismology, gravity, meteorology and geomagnetism. It includes two main facilities: (1) The seismo-gravimetric observatory (SGO), which was opened in 2002, and (2) the geomagnetic observatory (GMO), officially opened in 2014. Temporal variation of gravity is monitored at CO since autumn 2007 by the Superconducting Gravimeter GWR C025 (until November 2018) and, after a longer interruption, by GWR iGrav 050. The time series of gravity and barometric pressure from the iGrav SG 050 starts in April 2024. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 second and 1 minute. For a detailed description of the IGETS data base and the provided files see Voigt et al. (2016, https://doi.org/10.2312/GFZ.b103-16087).

Superconducting Gravimeter Data from Serrahn - Level 1

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 SG site “Serrahn” is located in the TERENO Observatory in the nort-eastern German lowlands. The observatory contributes to investigating the regional impact of climate and land use change. At the IGETS site Serrahn, the mean annual temperature is 8.8 °C and mean annual precipitation is 591 mm. The land cover is mainly characterized as a mixed forest, dominated by European beech and Scots pine. Influenced by the last glaciation in an outwash close to the terminal morraine, the uppermost soil layer of the site consists of aeolian sands up to a depth of 450 cm, followed by coarser sandy material with intercalated till layers. The unconfined groundwater level is at about 14 m below surface. There is hardly any human activity (e.g., traffic) at this quiet forest site. The nearest town is Neustrelitz at a distance of 5 km. Since December 2017, the superconducting gravimeter iGrav-033 is operated outdoors at this forest location (Latitude: 53.3392 N, Longitude: 13.17413 E, Elevation: 79.60 m). The gravimeter is installed in a dedicated field enclosure on top of a concrete pillar with an area of 1.1 m x 1.1 m at an elevation of 0.80 m above the terrain surface. The pillar has been build to a depth of 2.00 m below the surface. One additional pillar (also 1.1 m x 1.1 m, at surface level) is located right next to the iGrav installation and is used for repeated observations with absolute gravimeters (AG). At the site, meteorological (precipitation, air temperature, humidity, air pressure) and hydrological (groundwater, soil moisture, sapflow, throughfall) parameters are monitored by different sensors. Raw gravity and local atmospheric pressure records sampled at second intervals and the same records decimated at 1‐minute samples are provided as Level 1 products to the IGETS network.

Superconducting Gravimeter Data from Pecný - Level 2 pre-processed by station operators

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. Raw gravity and local atmospheric pressure records sampled at second and the same records decimated at 1‐minute samples are provided as Level 1 products of the IGETS network for the Pecný station (https://doi.org/10.5880/igets.pe.l1.001). The corrected 1-minute samples have been prepared by operators of the station, from raw decimated 1-minute samples, by following steps: 1) The 1-minute samples have been used to compute residual gravity signal by using the SG calibration factor and applying corrections from tides, atmosphere and polar motion. 2) These data have been associated with auxiliary data from the SG (Dewar Pressure, Tx/Ty balance, Neck temperature etc.) and information from LOG files. 3) Gaps have been created in the residual gravity signal according to auxiliary data and log files. Moreover, gaps were created also for large disturbances, where the residual signal exceeding 20 nm/s^2. 4) Gaps up to 24 hours were filled by a linear fit. 5) Spikes exceeding 5 nm/s^2 were removed by using TSOFT. 6) Steps were applied only in exceptional cases in accordance with LOG files. 7) The cleaned residual signal was converted to corrected 1-minute samples by using the same corrections and the calibration factor as used in 1). Therefore, the corrected 1-minute signal is again in units as the raw data (Volt). Note, since 31 October 2017, the OSG-050 is running at new site (NGL - new gravimetric laboratory at Pecný) according to https://doi.org/10.5880/igets.pe.l1.001.

Superconducting Gravimeter Data from Onsala - Level 1

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 Onsala station (code OS, instrument GWR OSG 054) was established in 2009 thanks to the financial support of the Committee for Infrastructure of the Swedish Research Council, until 2021, and of the Swedish geodetic survey Lantmäteriet since 2021. Continuous time-varying gravity and atmospheric pressure data from OS are integrated in the IGETS data base hosted by ISDC (Information System and Data Centre) at GFZ. The OS station (longitude: 11.9266 E; latitude: 57.3858 N and elevation: 7.93 m) is located at the Onsala Space Observatory, south of Gothenbourg, a well instrumented site for geodetic and meteorological studies (https://www.chalmers.se/en/researchinfrastructure/oso/Pages/default.aspx). An air-circulation system controls the humidity and temperature in the gravimeter house and there are 3 pillars available. Absolute gravity measurements are done every year by Lantmäteriet. - The time series of gravity and barometric pressure started in July 2009 and is going on. - The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 minute. 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). Rainfall data are also provided as auxiliary data to IGETS database. OS data are used in conjunction with projects of the Nordic Geodetic Commission (NKG) - Working Group for Geodynamics (https://www.nordicgeodeticcommission.com/working-group-of-geodynamics/). Interactive graphs are available at https://lab3.oso.chalmers.se/wx/gravimeter_data/

Superconducting Gravimeter Data from Membach - Level 1

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 Membach station is located near the river Vesdre. It consists of a 130 m long gallery excavated in the side of the valley that rises to the Hautes Fagnes plateau. At the end of the gallery, there are two rooms, located at ~45 m below the ground surface. Room 1 is dedicated to absolute gravity and seismic measurements; room 2 houses the superconducting gravimeter. The structure of the gallery and the rooms is in reinforced concrete. It was built in the early 1970s to monitor the seismic activity in the vicinity of the Gileppe and Eupen water reservoirs. Works were performed contemporeanously with the raising of the Gileppe dam. The gallery has been excavated in low-porosity argillaceous sandstone with quartzitic beds. As a function of rainfall and seasonal effects, gravity variations up to 40 nms-2 have been observed, and are mostly due to groundwater changes in the vadose zone above the underground laboratory (Van Camp et al., 2006). Strong rainfall induces rapid gravity decreases (Meurers et al 2007; Delobbe et al., 2019). At the surface, a beech forest. Absolute gravity measurements have been performed on average every month since 1996, using the FG5#202 gravimeter and the station is also the reference point for the Belgian gravity network. The SG GWR#C021 has been operating continuously since 1995 August so that, since 2017 September 18, it holds both records for the longest continuous time spent measuring gravity variations in the same place and for the longest superconducting levitation of an artefact (Van Camp et al., 2017). For high precision works like Earth tides analysis on long time series, data should not be used before 1998 June 12, when the original "TIDE" card in the SG electronics was replaced by the "GGP" one. Filters are different, and so are the transfer functions. Moreover, in this early period, the SG suffered from numerous technical issues, causing several changes in the amplitude and phase calibrations and making it difficult to ensure that the data are as reliable as after 1998 June.

Superconducting Gravimeter Data from Rochefort - Level 1

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 2014 December the Royal Observatory of Belgium installed the iGrav #019 at the surface site of the Rochefort "Lorette" cave laboratory. The Lorette cave is one of several cavities that belong to the Wamme–Lomme karst system, a 10 km long karst area. At the surface of the site, a small and solid building, located at the border of a large sinkhole, hosts the gravity laboratory, which is thermally stabilized at ~25°C by a heater, excepted during a few days each summer when the temperature may increase above that level. The iGrav #019 is installed directly on the bedrock (limestone) in a 1 m deep shaft. Two meters away from the iGrav there is a pillar of cement (60% sand, 40% cement, no iron nor stones) founded 1 meter deep on the bedrock and on which absolute gravity measurements are performed 10 times or more per year with the FG5#202 absolute gravimeter. See description in Fig A7 in Van Camp et al., 2017. As this instrument was installed among others to investigate flash floods in the caves, it regularly monitors sudden changes in gravity reaching 50-100 nm/s², especially during the winter (Watlet et al., 2020). This should be considered when performing e.g. tidal analyses.

Superconducting Gravimeter Data from Aubure - Level 1

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 Aubure station (code AU) was established in 2017 thanks to the financial support of the EQUIPEX CRITEX (https://www.critex.fr/). Continuous time-varying gravity and atmospheric pressure data from AU are integrated in the IGETS data base hosted by ISDC (Information System and Data Centre) at GFZ. The operation and maintenance of the AU instrumentation is done by staff at EOST/ITES in Strasbourg, France. The AU station (longitude: 7.1967 E; latitude: 48.2170 N and elevation: 1151.9 m) is located in the Strengbach catchment in the Vosges mountains, a well instrumented and studied site by the Hydro-Geochemical Observatory of the Environment of Strasbourg (http://ohge.unistra.fr/). The time series of gravity and barometric pressure from iGrav 030 starts in June 2017 and is going on. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 minute. For a detailed description of the IGETS data base and the provided files see Voigt et al. (2016, https://doi.org/10.2312/GFZ.b103-16087).

Superconducting Gravimeter Data from Strasbourg - Level 1

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 stopped in November 2018. The new SG iOSG#23 was installed in February 2016. Both meters ran side by side between February 2016 and November 2018 in order to perform an intercomparison in terms of noise level (Rosat & Hinderer 2018) and instrumental drift. The time series of gravity and barometric pressure from SG C026 starts in July 1996 and ends in November 2018. The time series of gravity and barometric pressure from iOSG#23 starts in February 2016 and is going on. 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/).

Superconducting Gravimeter Data from Potsdam - Level 1

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).

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