Superconducting gravimeter (SG) – its contribution to the observation of the Earth System

Contributions of superconducting gravimeters to the study of the Earth System, including the study of geophysical and geodynamic phenomena, and the establishment of the International Terrestrial Gravity Reference Frame (ITGRF)

Gravity reference at the Argentinean–German Geodetic Observatory (AGGO) by co-location of superconducting and absolute gravity measurements

The Argentinean–German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina. Two high-precision gravity meters are installed at AGGO: the superconducting gravimeter SG038, which is in operation since December 2015, and the absolute gravimeter FG5-227, which has provided absolute gravity measurements since January 2018. By co-location of gravity observations from both meters between January 2018 and March 2019, calibration factor and instrumental drift of the SG038 were determined. The calibration factor of the SG038 was estimated by different strategies: from tidal models, dedicated absolute gravity measurements over several days and a joint approach (including the determination of the instrumental drift) using all available absolute gravity data. The final calibration factor differs from the determination at the previous station, the transportable integrated geodetic observatory, in Concepcion, Chile, by only 0.7‰, which does not imply a significant change. From the combined approach also the mean absolute level of the SG was determined, allowing to predict absolute gravity values from the SG at any time based on a repeatability of 12nm/s2 for the FG5-227 at AGGO. Such a continuous gravity reference function provides the basis for a comparison site for absolute gravimeters in the frame of the international gravity reference frame for South America and the Caribbean. However, it requires the assessment of the total error budget of the FG5-227, including the link to the international comparisons, which will be subject of future efforts.Fil: Antokoletz, Ezequiel Darío. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Wziontek, Hartmut. Federal Agency for Cartography and Geodesy; AlemaniaFil: Tocho, Claudia. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Falk, Reinhard. Federal Agency for Cartography and Geodesy; Alemani

A tidal model for the Argentinean-German Geodetic Observatory (AGGO) by using superconducting gravity observations of SG038

El Observatorio Argentino-Alemán de Geodesia (AGGO) es un observatorio fundamental de geodesia ubicado en las cercanías de la ciudad de La Plata, Argentina. AGGO cuenta con las principales técnicas geodésicas espaciales, GNSS, VLBI y SLR. Por otra parte, AGGO posee un Laboratorio de Gravimetría, donde el gravímetro superconductor (SG) SG038 realiza mediciones en forma continua de las variaciones de gravedad, desde diciembre del año 2015. Además, el gravímetro absoluto FG5-227 provee un valor de gravedad absoluto de referencia para AGGO y para Latinoamérica desde enero del año 2018. En este trabajo se presenta un modelo de mareas obtenido a partir del análisis de tres años de observaciones del SG. Los SGs son capaces de medir variaciones de la gravedad en un gran espectro de amplitudes y frecuencias, desde mareas terrestres hasta efectos hidrológicos. Para analizar distintos efectos en las observaciones de un SG, primero debe realizarse un cuidadoso tratamiento de la señal observada. Para esto se obtuvieron los residuos preliminares, luego de eliminar las principales fuentes de variaciones de gravedad. Saltos y picos ocasionados por terremotos, cortes de luz, etc., fueron eliminados de la señal residual y a su vez filtrada, obteniendo una señal suave y continua. Luego, las señales de mareas terrestres y carga oceánica fueron restituidas a la señal residual. El procesamiento de la señal resultante se realizó con la última versión del software ETERNA ETA34-X, incluyendo el grado 3 del potencial de marea de ciertas ondas de marea en el análisis de marea. Como resultado del análisis de tres años de observaciones, se obtuvieron los parámetros de marea de 55 grupos de onda. En segundo lugar, se ha analizado el impacto de distintos modelos de marea oceánica en los parámetros, con el fin de separar los efectos de marea terrestre y carga oceánica.The Argentinean-German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina. All relevant space geodetic techniques are established at AGGO: GNSS, VLBI and SLR. A Gravity Lab is also installed, where the superconducting gravimeter (SG) SG038 has been continuously measuring gravity variations since December 2015. Moreover, the absolute gravimeter FG5-227 has provided a gravity reference value for the Observatory and Latin America since January 2018. Through the analysis of three years of superconducting gravity data, an Earth tidal model is presented. The SGs are capable to measure gravity variations in a wide range of amplitudes and frequencies, from Earth tides to hydrological effects. In order to analyse different effects in the SG observations, a careful pre-processing of the signal has to be done before. To do so, the preliminary residuals were obtained by subtracting the principal constituents of the signal. Spikes caused by earthquakes were eliminated and a few gaps were filled. The residuals were then filtered to obtain a smooth and continuous signal. Afterwards, Earth tides and ocean tide loading signals that were previously subtracted, were restored to the corrected residuals. The tidal analysis was performed with the last version of the ETERNA ETA34-X software, including independent estimates of degree 3 of the potential of some tidal constituents. After the tidal analysis of three years of SG observations, parameters of 55 tidal constituents were obtained. Moreover, in order to separate the effects of Earth tides and ocean tide loading, different ocean tide models were compared.Facultad de Ciencias Astronómicas y Geofísica

A tidal model for the Argentinean-German Geodetic Observatory (AGGO) by using superconducting gravity observations of SG038

El Observatorio Argentino-Alemán de Geodesia (AGGO) es un observatorio fundamental de geodesia ubicado en las cercanías de la ciudad de La Plata, Argentina. AGGO cuenta con las principales técnicas geodésicas espaciales, GNSS, VLBI y SLR. Por otra parte, AGGO posee un Laboratorio de Gravimetría, donde el gravímetro superconductor (SG) SG038 realiza mediciones en forma continua de las variaciones de gravedad, desde diciembre del año 2015. Además, el gravímetro absoluto FG5-227 provee un valor de gravedad absoluto de referencia para AGGO y para Latinoamérica desde enero del año 2018. En este trabajo se presenta un modelo de mareas obtenido a partir del análisis de tres años de observaciones del SG. Los SGs son capaces de medir variaciones de la gravedad en un gran espectro de amplitudes y frecuencias, desde mareas terrestres hasta efectos hidrológicos. Para analizar distintos efectos en las observaciones de un SG, primero debe realizarse un cuidadoso tratamiento de la señal observada. Para esto se obtuvieron los residuos preliminares, luego de eliminar las principales fuentes de variaciones de gravedad. Saltos y picos ocasionados por terremotos, cortes de luz, etc., fueron eliminados de la señal residual y a su vez filtrada, obteniendo una señal suave y continua. Luego, las señales de mareas terrestres y carga oceánica fueron restituidas a la señal residual. El procesamiento de la señal resultante se realizó con la última versión del software ETERNA ETA34-X, incluyendo el grado 3 del potencial de marea de ciertas ondas de marea en el análisis de marea. Como resultado del análisis de tres años de observaciones, se obtuvieron los parámetros de marea de 55 grupos de onda. En segundo lugar, se ha analizado el impacto de distintos modelos de marea oceánica en los parámetros, con el fin de separar los efectos de marea terrestre y carga oceánica.The Argentinean-German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina. All relevant space geodetic techniques are established at AGGO: GNSS, VLBI and SLR. A Gravity Lab is also installed, where the superconducting gravimeter (SG) SG038 has been continuously measuring gravity variations since December 2015. Moreover, the absolute gravimeter FG5-227 has provided a gravity reference value for the Observatory and Latin America since January 2018. Through the analysis of three years of superconducting gravity data, an Earth tidal model is presented. The SGs are capable to measure gravity variations in a wide range of amplitudes and frequencies, from Earth tides to hydrological effects. In order to analyse different effects in the SG observations, a careful pre-processing of the signal has to be done before. To do so, the preliminary residuals were obtained by subtracting the principal constituents of the signal. Spikes caused by earthquakes were eliminated and a few gaps were filled. The residuals were then filtered to obtain a smooth and continuous signal. Afterwards, Earth tides and ocean tide loading signals that were previously subtracted, were restored to the corrected residuals. The tidal analysis was performed with the last version of the ETERNA ETA34-X software, including independent estimates of degree 3 of the potential of some tidal constituents. After the tidal analysis of three years of SG observations, parameters of 55 tidal constituents were obtained. Moreover, in order to separate the effects of Earth tides and ocean tide loading, different ocean tide models were compared.Fil: Antokoletz, Ezequiel Darío. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Gravimetría; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Tocho, Claudia. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Gravimetría; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Wziontek, Hartmut. Federal Agency for Cartography and Geodesy; Alemani

Mobile quantum gravity sensor with unprecedented stability

Changes of surface gravity on Earth are of great interest in geodesy, earth sciences and natural resource exploration. They are indicative of Earth system's mass redistributions and vertical surface motion, and are usually measured with falling corner-cube- and superconducting gravimeters (FCCG and SCG). Here we report on absolute gravity measurements with a mobile quantum gravimeter based on atom interferometry. The measurements were conducted in Germany and Sweden over periods of several days with simultaneous SCG and FCCG comparisons. They show the best-reported performance of mobile atomic gravimeters to date with an accuracy of 39 nm/s^2, long-term stability of 0,5 nm/s^2 and short-term noise of 96 nm/s^2/(Hz)^1/2. These measurements highlight the unique properties of atomic sensors. The achieved level of performance in a transportable instrument enables new applications in geodesy and related Fields, such as continuous absolute gravity monitoring with a single instrument under rough environmental conditions

Mobile quantum gravity sensor with unprecedented stability

Changes of surface gravity on Earth are of great interest in geodesy, earth sciences and natural resource exploration. They are indicative of Earth system's mass redistributions and vertical surface motion, and are usually measured with falling corner-cube- and superconducting gravimeters (FCCG and SCG). Here we report on absolute gravity measurements with a mobile quantum gravimeter based on atom interferometry. The measurements were conducted in Germany and Sweden over periods of several days with simultaneous SCG and FCCG comparisons. They show the best-reported performance of mobile atomic gravimeters to date with an accuracy of 39nm/s2, long-term stability of 0.5nm/s2 and short-term noise of 96nm/s2/√Hz. These measurements highlight the unique properties of atomic sensors. The achieved level of performance in a transportable instrument enables new applications in geodesy and related fields, such as continuous absolute gravity monitoring with a single instrument under rough environmental conditions.Peer Reviewe

Non-Tidal Ocean Loading Correction for the Argentinean-German Geodetic Observatory Using an Empirical Model of Storm Surge for the Río de la Plata

The Argentinean-German Geodetic Observatory is located 13 km from the Rio de la Plata, in an area that is frequently affected by storm surges that can vary the level of the river over ±3 m. Water-level information from seven tide gauge stations located in the Rio de la Plata are used to calculate every hour an empirical model of water heights (tidal + non-tidal component) and an empirical model of storm surge (non-tidal component) for the period 01/2016–12/2016. Using the SPOTL software, the gravimetric response of the models and the tidal response are calculated, obtaining that for the observatory location, the range of the tidal component (3.6 nm/s²) is only 12% of the range of the non-tidal component (29.4 nm/s²). The gravimetric response of the storm surge model is subtracted from the superconducting gravimeter observations, after applying the traditional corrections, and a reduction of 7% of the RMS is obtained. The wavelet transform is applied to the same series, before and after the non-tidal correction, and a clear decrease in the spectral energy in the periods between 2 and 12 days is identify between the series. Using the same software East, North and Up displacements are calculated, and a range of 3, 2, and 11 mm is obtained, respectively. The residuals obtained after applying the non-tidal correction allow to clearly identify the influence of rain events in the superconducting gravimeter observations, indicating the need of the analysis of this, and others, hydrological and geophysical effects.Facultad de Ciencias Astronómicas y Geofísica

Modeling gravimetric signatures of third-degree ocean tides and their detection in superconducting gravimeter records

We employ the barotropic, data-unconstrained ocean tide model TiME to derive an atlas for degree-3 tidal constituentsincluding monthly to terdiurnal tidal species. The model is optimized with respect to the tide gauge data set TICON-td that isextended to include the respective tidal constituents of diurnal and higher frequencies. The tide gauge validation shows a rootmean-square (RMS) deviation of 0.9–1.3mm for the individual species. We further model the load tide-induced gravimetric signals by two means (1) a global load Love number approach and (2) evaluating Greens-integrals at 16 selected locations of superconducting gravimeters. The RMS deviation between the amplitudes derived using both methods is below 0.5 nGal (1 nGal = 0.01 nm/s2 ) when excluding near-coastal gravimeters. Utilizing ETERNA-x, a recently upgraded and reworked tidal analysis software, we additionally derive degree-3 gravimetric tidal constituents for these stations, based on a hypothesis-free wave grouping approach.We demonstrate that this analysis is feasible, yielding amplitude predictions of only a few 10 nGal, and that it agrees with the modeled constituents on a level of 63–80% of the mean signal amplitude. Larger deviations are only found for lowest amplitude signals, near-coastal stations, or shorter and noisier data sets

Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in la Plata

The Argentine-German Geodetic Observatory (AGGO) is one of the very few sites in the Southern Hemisphere equipped with comprehensive cutting-edge geodetic instrumentation. The employed observation techniques are used for a wide range of geophysical applications. The data set provides gravity time series and selected gravity models together with the hydrometeorological monitoring data of the observatory. These parameters are of great interest to the scientific community, e.g. for achieving accurate realization of terrestrial and celestial reference frames. Moreover, the availability of the hydrometeorological products is beneficial to inhabitants of the region as they allow for monitoring of environmental changes and natural hazards including extreme events. The hydrological data set is composed of time series of groundwater level, modelled and observed soil moisture content, soil temperature, and physical soil properties and aquifer properties. The meteorological time series include air temperature, humidity, pressure, wind speed, solar radiation, precipitation, and derived reference evapotranspiration. These data products are extended by gravity models of hydrological, oceanic, La Plata estuary, and atmospheric effects. The quality of the provided meteorological time series is tested via comparison to the two closest WMO (World Meteorological Organization) sites where data are available only in an inferior temporal resolution. The hydrological series are validated by comparing the respective forward-modelled gravity effects to independent gravity observations reduced up to a signal corresponding to local water storage variation. Most of the time series cover the time span between April 2016 and November 2018 with either no or only few missing data points.Fil: Mikolaj, Michal. German Research Centre for Geosciences; AlemaniaFil: Güntner, Andreas. German Research Centre for Geosciences; Alemania. Universitat Potsdam; AlemaniaFil: Brunini, Claudio Antonio. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Laboratorio Geo - Aggo.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Wziontek, Hartmut. Federal Agency for Cartography and Geodesy; AlemaniaFil: Gende, Mauricio Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Schröder, Stephan. German Research Centre for Geosciences; AlemaniaFil: Cassino, Augusto Martin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Laboratorio Geo - Aggo.; ArgentinaFil: Pasquaré, Alfredo Oscar. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Laboratorio Geo - Aggo. Observatorio Geodesico Argentino Aleman.; ArgentinaFil: Reich, Marvin. German Research Centre for Geosciences; AlemaniaFil: Hartmann, Anne. German Research Centre for Geosciences; AlemaniaFil: Oreiro, Fernando Ariel. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Pendiuk, Jonathan. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Guarracino, Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Antokoletz, Ezequiel Darío. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata

The Argentine-German Geodetic Observatory (AGGO) is one of the very few sites in the Southern Hemisphere equipped with comprehensive cutting-edge geodetic instrumentation. The employed observation techniques are used for a wide range of geophysical applications. The data set provides gravity time series and selected gravity models together with the hydrometeorological monitoring data of the observatory. These parameters are of great interest to the scientific community, e.g. for achieving accurate realization of terrestrial and celestial reference frames. Moreover, the availability of the hydrometeorological products is beneficial to inhabitants of the region as they allow for monitoring of environmental changes and natural hazards including extreme events. The hydrological data set is composed of time series of groundwater level, modelled and observed soil moisture content, soil temperature, and physical soil properties and aquifer properties. The meteorological time series include air temperature, humidity, pressure, wind speed, solar radiation, precipitation, and derived reference evapotranspiration. These data products are extended by gravity models of hydrological, oceanic, La Plata estuary, and atmospheric effects. The quality of the provided meteorological time series is tested via comparison to the two closest WMO (World Meteorological Organization) sites where data are available only in an inferior temporal resolution. The hydrological series are validated by comparing the respective forward-modelled gravity effects to independent gravity observations reduced up to a signal corresponding to local water storage variation. Most of the time series cover the time span between April 2016 and November 2018 with either no or only few missing data points. The data set is available at https://doi.org/10.5880/GFZ.5.4.2018.001 (Mikolaj et al., 2018).Puede accederse a los datos primarios de este trabajo haciendo clic en "Documentos relacionados".Facultad de Ciencias Astronómicas y Geofísica