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Jacques Hinderer - One of the best experts on this subject based on the ideXlab platform.
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Analyses of a 426-Day Record of Seafloor Gravity and Pressure Time Series in the North Sea
Pure and Applied Geophysics, 2017Co-Authors: S. Rosat, Jacques Hinderer, B. Escot, J.-p. BoyAbstract:Continuous gravity observations of ocean and solid tides are usually done with land-based Gravimeters. In this study we analyze a 426-day record of time-varying gravity acquired by an ocean-bottom Scintrex spring Gravimeter between August 2005 and November 2006 at the Troll A site located in the North Sea at a depth of 303 m. Sea-bottom pressure changes were also recorded in parallel with a Paroscientific quartz pressure sensor. From these data, we show a comparison of the noise level of the sea-floor Gravimeter with respect to two standard land-based relative Gravimeters: a Scintrex CG5 and a GWR Superconducting Gravimeter that were recording at the J9 gravimetric observatory of Strasbourg (France). We also compare the analyzed gravity records with the predicted solid and oceanic tides. The oceanic tides recorded by the seafloor barometer are also analyzed and compared to the predicted ones using FES2014b ocean model. Observed diurnal and semi-diurnal components are in good agreement with FES2014b predictions. Smallest constituents reflect some differences that may be attributed to non-linearity occurring at the Troll A site. Using the barotropic TUGO-m dynamic model of sea level response to ECMWF atmospheric pressure and winds forcing, we show a good agreement with the detided ocean-bottom pressure residuals. About 4-hPa of standard deviation of remaining sea-bottom pressure are however not explained by the TUGO-m dynamic model.
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Leveling and hybrid gravimetry monitoring applied to geothermal sites of Soultz-sous- Forêts and Rittershoffen, Rhine Graben, France
2016Co-Authors: Gilbert Ferhat, Jacques Hinderer, Yassine Abdelfettah, Basile Hector, Umberto Riccardi, M Lopez-barraza, Emmanuel Clédat, Marta Calvo Garcia-maroto, J.-d BernardAbstract:Here we report on some case histories of geodetic and gravity surveys for monitoring of geothermal sites. The monitoring of a geothermal reservoir by hybrid gravimetry combining different types of instruments (permanent superconducting Gravimeter, absolute ballistic Gravimeter and micro-Gravimeters) is presented. A relative gravimetric network equipped with levelling benchmarks was designed and surveyed at annual frequencies (2013, 2014 and 2015 for gravity measurements, 2014 and 2015 for the levelling). Repetition of high precision relative gravity measurements on a network developed around a reference station, which is regularly measured with both relative and absolute Gravimeters, leads to the knowledge of the time and space changes in surface gravity. The observed gravity changes can be linked to the natural or anthropic activities of the reservoir. A feasibility study using this methodology is applied to two geothermal sites of Soultz-sous-Forêts and Rittershoffen in the Alsace region (France) in the Rhine graben (Hinderer et al. 2015).
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Monitoring of a geothermal reservoir by hybrid gravimetry; feasibility study applied to the Soultz-sous-Forêts and Rittershoffen sites in the Rhine graben
Geothermal Energy, 2015Co-Authors: Jacques Hinderer, Yassine Abdelfettah, Basile Hector, Gilbert Ferhat, Marta Calvo, Umberto Riccardi, Jeandaniel BernardAbstract:The study is devoted to the monitoring of a geothermal reservoir by hybrid gravimetry combining different types of instruments (permanent superconducting Gravimeter, absolute ballistic Gravimeter, and micro-Gravimeters) and different techniques of measurements (both time-discrete and recording data collection). Using a micro-gravimetric repetition network around a reference station, which is regularly measured, leads to the knowledge of the time and space changes in surface gravity. Such changes can be linked to the natural or anthropic activities of the reservoir. A feasibility study using this methodology is applied to two geothermal sites in the Alsace region (France) of the Rhine graben. We show the results in terms of gravity double differences from weekly repetitions of a network of 11 stations around the geothermal reservoir of Soultz-sous-Forêts, separated into 5 loops during July–August 2013 and 2014 as well as preliminary results from 2 stations near Rittershoffen (ECOGI). We point out the importance of a precise leveling of the gravity points for the control of the vertical deformation. A first modeling of surface gravity changes induced by realistic geothermal density perturbations (Newtonian attraction) is computed in the frame of the existing geological model and leads to gravity changes below the μGal level being hence undetectable. However, and for the same case, borehole gravity modeling showed a significant anomaly with depth that can be used as a complementary monitoring method. We show that in the limit of our uncertainties (SD ~ 5 μGal), we do not detect any significant gravity change on the geothermal site of Soultz in agreement with the fact that there was indeed no geothermal activity during our analysis period. On the contrary, the measurements near Rittershoffen show a signal above the noise level which correlates in time with a production test but cannot be explained in terms of Newtonian attraction effects according to our basic numerical simulation.
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Time stability of spring and superconducting Gravimeters through the analysis of very long gravity records
Journal of Geodynamics, 2014Co-Authors: Marta Calvo, Jacques Hinderer, Séverine Rosat, Hilaire Legros, Jean-paul Boy, Bernard Ducarme, Walter ZürnAbstract:Long gravity records are of great interest when performing tidal analyses. Indeed, long series enable to separate contributions of near-frequency waves and also to detect low frequency signals (e.g. long period tides and polar motion). In addition to the length of the series, the quality of the data and the temporal stability of the noise are also very important. We study in detail some of the longest gravity records available in Europe: 3 data sets recorded with spring Gravimeters in Black Forest Observatory (Germany, 1980-2012), Walferdange (Luxemburg, 1980-1995) and Potsdam (Germany, 1974-1998) and several superconducting Gravimeters (SGs) data sets, with at least 9 years of continuous records, at different European GGP (Global Geodynamics Project) sites (Bad Homburg, Brussels, Medicina, Membach, Moxa, Vienna, Wettzell and Strasbourg). The stability of each instrument is investigated using the temporal variations of tidal parameters (amplitude factor and phase difference) for the main tidal waves (O1, K1, M2 and S2) as well as the M2/O1 factor ratio, the later being insensitive to the instrumental calibration. The long term stability of the tidal observations is also dependent on the stability of the scale factor of the relative Gravimeters. Therefore we also check the time stability of the scale factor for the superconducting Gravimeter C026 installed at the J9 Gravimetric Observatory of Strasbourg (France), using numerous calibration experiments carried out by co-located absolute Gravimeter (AG) measurements during the last 15 years. The reproducibility of the scale factor and the achievable precision are investigated by comparing the results of different calibration campaigns. Finally we present a spectrum of the 25 years of SG records at J9 Observatory, with special attention to small amplitude tides in the semi-diurnal and diurnal bands, as well as to the low frequency part.
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Analysis of co-located measurements made with a LaCoste&Romberg Graviton-EG Gravimeter and two superconducting Gravimeters at Strasbourg (France) and Yebes (Spain)
Acta Geodaetica et Geophysica, 2014Co-Authors: José Arnoso, Jacques Hinderer, Umberto Riccardi, B. Cordoba, Fuensanta González MontesinosAbstract:Two experiments of intercomparison between the LaCoste&Romberg Graviton-EG1194 spring Gravimeter and the superconducting Gravimeters SG-026 and OSG-064, operating respectively at J9-Strasbourg (France) and CDT-Yebes (Spain), were analyzed. The main objective was to check the instrumental response of the spring meter, both in amplitude and phase as well as its time stability. A general conclusion is that normalization factors have been obtained with a similar ratio for main diurnal constituent O1 at both observing sites. The accuracy of scale factors was determined at the level of 0.03 % (at J9-Strasbourg) and 0.1 % (at CDT-Yebes). For the semidiurnal constituent M2, slight differences were found at J9-Strasbourg, which would require further investigations. Site effects were also demonstrated by considering the different response of the spring Gravimeter to tilts and atmospheric pressure variations at both sites
Olivier Francis - One of the best experts on this subject based on the ideXlab platform.
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Long‐Term Stability of Tilt‐Controlled gPhoneX Gravimeters
Journal of Geophysical Research : Solid Earth, 2019Co-Authors: Benjamin Fores, Gilbert Klein, Nicolas Le Moigne, Olivier FrancisAbstract:Spring relative Gravimeters are considered too unstable to provide useful information on long‐term gravity variations. In this paper, we prove that the new generation of spring Gravimeter gPhoneX can reach long‐term stability at the μGal level (10 nm s−2) when the verticality of the Gravimeter is maintained, if the instrumental drift can be correctly estimated. We conducted two comparisons with different gPhoneXs in different observatories and environmental conditions. In the “Walferdange Underground Laboratory for Geodynamics” in Luxembourg, we compared time series from the gPhoneX (with and without tilt control), with data from a superconducting Gravimeter. We found an agreement at the μGal level when the tilt control is switched on. We validated this result by repeating the experiment at the “Geodesy in Karstic Environment” observatory in the south of France. The fit between the superconducting Gravimeter and the gPhoneX hourly values gives similar results at all frequencies over 276 days of measurements. The linear correlation coefficient between the gPhoneX and superconducting Gravimeter reaches 0.99, with a misfit of 6.0 nm s−2. We demonstrated that tilt‐controlled gPhoneXs are suitable for long‐term gravity monitoring.
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Stability comparison of two absolute Gravimeters: optical versus atomic interferometers
Metrologia, 2014Co-Authors: Pierre Gillot, Olivier Francis, Arnaud Landragin, Franck Pereira Dos Santos, Sébastien MerletAbstract:We report the direct comparison between the stabilities of two mobile absolute Gravimeters of different technology: the LNE-SYRTE Cold Atom Gravimeter and FG5X#216 of the Université du Luxembourg. These instruments rely on two different principles of operation: atomic and optical interferometry. The comparison took place in the Walferdange Underground Laboratory for Geodynamics in Luxembourg, at the beginning of the last International Comparison of Absolute Gravimeters, ICAG-2013. We analyse a 2h10 duration common measurement, and find that the CAG shows better immunity with respect to changes in the level of vibration noise, as well as a slightly better short term stability.
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Stability comparison of two absolute Gravimeters: optical versus atomic interferometers
Metrologia, 2014Co-Authors: Pierre Gillot, Olivier Francis, Arnaud Landragin, Franck Pereira Dos Santos, Sébastien MerletAbstract:We report the direct comparison between the stabilities of two mobile absolute Gravimeters of different technology: the LNE-SYRTE Cold Atom Gravimeter and FG5X\#216 of the Universit\'e du Luxembourg. These instruments rely on two different principles of operation: atomic and optical interferometry. The comparison took place in the Walferdange Underground Laboratory for Geodynamics in Luxembourg, at the beginning of the last International Comparison of Absolute Gravimeters, ICAG-2013. We analyse a 2h10 duration common measurement, and find that the CAG shows better immunity with respect to changes in the level of vibration noise, as well as a slightly better short term stability.
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The European Comparison of Absolute Gravimeters 2011 (ECAG-2011) in Walferdange, Luxembourg: results and recommendations
Metrologia, 2013Co-Authors: Olivier Francis, Christian Rothleitner, Gilbert Klein, Henri Baumann, Tomas Volarik, Marc Seil, Nicolas Dando, Ray Tracey, Christian Ullrich, Stefaan CasteleinAbstract:We present the results of the third European Comparison of Absolute Gravimeters held in Walferdange, Grand Duchy of Luxembourg, in November 2011. Twenty-two Gravimeters from both metrological and non-metrological institutes are compared. For the first time, corrections for the laser beam diffraction and the self-attraction of the Gravimeters are implemented. The gravity observations are also corrected for geophysical gravity changes that occurred during the comparison using the observations of a superconducting Gravimeter. We show that these corrections improve the degree of equivalence between the Gravimeters. We present the results for two different combinations of data. In the first one, we use only the observations from the metrological institutes. In the second solution, we include all the data from both metrological and non-metrological institutes. Those solutions are then compared with the official result of the comparison published previously and based on the observations of the metrological institutes and the gravity differences at the different sites as measured by non-metrological institutes. Overall, the absolute gravity meters agree with one another with a standard deviation of 3.1 µGal. Finally, the results of this comparison are linked to previous ones. We conclude with some important recommendations for future comparisons.
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Results of the first North American comparison of absolute Gravimeters, NACAG-2010
Journal of Geodesy, 2012Co-Authors: D. Schmerge, Olivier Francis, J. Liard, J. Henton, D. Ingles, D. Jones, Jeffrey R. Kennedy, K. Krauterbluth, David B. Newell, Roger W. SandsAbstract:The first North American Comparison of absolute Gravimeters (NACAG-2010) was hosted by the National Oceanic and Atmospheric Administration at its newly renovated Table Mountain Geophysical Observatory (TMGO) north of Boulder, Colorado, in October 2010. NACAG-2010 and the renovation of TMGO are part of NGS\u2019s GRAV-D project (Gravity for the Redefinition of the American Vertical Datum). Nine absolute Gravimeters from three countries participated in the comparison. Before the comparison, the Gravimeter operators agreed to a protocol describing the strategy to measure, calculate, and present the results. Nine sites were used to measure the free-fall acceleration of g. Each Gravimeter measured the value of g at a subset of three of the sites, for a total set of 27 g-values for the comparison. The absolute Gravimeters agree with one another with a standard deviation of 1.6 \u3bcGal (1 Gal \u2261 1 cm s \u22122). The minimum and maximum offsets are \u22122.8 and 2.7 \u3bcGal. This is an excellent agreement and can be attributed to multiple factors, including Gravimeters that were in good working order, good operators, a quiet observatory, and a short duration time for the experiment. These results can be used to standardize gravity surveys internationally.Peer reviewed: YesNRC publication: Ye
Marta Calvo - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of a geothermal reservoir by hybrid gravimetry; feasibility study applied to the Soultz-sous-Forêts and Rittershoffen sites in the Rhine graben
Geothermal Energy, 2015Co-Authors: Jacques Hinderer, Yassine Abdelfettah, Basile Hector, Gilbert Ferhat, Marta Calvo, Umberto Riccardi, Jeandaniel BernardAbstract:The study is devoted to the monitoring of a geothermal reservoir by hybrid gravimetry combining different types of instruments (permanent superconducting Gravimeter, absolute ballistic Gravimeter, and micro-Gravimeters) and different techniques of measurements (both time-discrete and recording data collection). Using a micro-gravimetric repetition network around a reference station, which is regularly measured, leads to the knowledge of the time and space changes in surface gravity. Such changes can be linked to the natural or anthropic activities of the reservoir. A feasibility study using this methodology is applied to two geothermal sites in the Alsace region (France) of the Rhine graben. We show the results in terms of gravity double differences from weekly repetitions of a network of 11 stations around the geothermal reservoir of Soultz-sous-Forêts, separated into 5 loops during July–August 2013 and 2014 as well as preliminary results from 2 stations near Rittershoffen (ECOGI). We point out the importance of a precise leveling of the gravity points for the control of the vertical deformation. A first modeling of surface gravity changes induced by realistic geothermal density perturbations (Newtonian attraction) is computed in the frame of the existing geological model and leads to gravity changes below the μGal level being hence undetectable. However, and for the same case, borehole gravity modeling showed a significant anomaly with depth that can be used as a complementary monitoring method. We show that in the limit of our uncertainties (SD ~ 5 μGal), we do not detect any significant gravity change on the geothermal site of Soultz in agreement with the fact that there was indeed no geothermal activity during our analysis period. On the contrary, the measurements near Rittershoffen show a signal above the noise level which correlates in time with a production test but cannot be explained in terms of Newtonian attraction effects according to our basic numerical simulation.
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Time stability of spring and superconducting Gravimeters through the analysis of very long gravity records
Journal of Geodynamics, 2014Co-Authors: Marta Calvo, Jacques Hinderer, Séverine Rosat, Hilaire Legros, Jean-paul Boy, Bernard Ducarme, Walter ZürnAbstract:Long gravity records are of great interest when performing tidal analyses. Indeed, long series enable to separate contributions of near-frequency waves and also to detect low frequency signals (e.g. long period tides and polar motion). In addition to the length of the series, the quality of the data and the temporal stability of the noise are also very important. We study in detail some of the longest gravity records available in Europe: 3 data sets recorded with spring Gravimeters in Black Forest Observatory (Germany, 1980-2012), Walferdange (Luxemburg, 1980-1995) and Potsdam (Germany, 1974-1998) and several superconducting Gravimeters (SGs) data sets, with at least 9 years of continuous records, at different European GGP (Global Geodynamics Project) sites (Bad Homburg, Brussels, Medicina, Membach, Moxa, Vienna, Wettzell and Strasbourg). The stability of each instrument is investigated using the temporal variations of tidal parameters (amplitude factor and phase difference) for the main tidal waves (O1, K1, M2 and S2) as well as the M2/O1 factor ratio, the later being insensitive to the instrumental calibration. The long term stability of the tidal observations is also dependent on the stability of the scale factor of the relative Gravimeters. Therefore we also check the time stability of the scale factor for the superconducting Gravimeter C026 installed at the J9 Gravimetric Observatory of Strasbourg (France), using numerous calibration experiments carried out by co-located absolute Gravimeter (AG) measurements during the last 15 years. The reproducibility of the scale factor and the achievable precision are investigated by comparing the results of different calibration campaigns. Finally we present a spectrum of the 25 years of SG records at J9 Observatory, with special attention to small amplitude tides in the semi-diurnal and diurnal bands, as well as to the low frequency part.
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Study of the Time Stability of Tides Using a Long Term (1973-2011) Gravity Record at Strasbourg, France
2014Co-Authors: Marta Calvo, Jacques Hinderer, J.-p. Boy, Séverine Rosat, Hilaire Legros, U. RiccardiAbstract:The Gravimetric Observatory J9 located near Strasbourg (France), has a long history of recording solid Earth tides. We present here one of the longest available gravity records (1973-2011) from three different instruments operating at the J9 station: a LaCoste-Romberg spring Gravimeter (ET005) from 1973 to 1985, a GWR (TT70-T005) superconducting Gravimeter from 1987 to 1996 and a GWR compact superconducting Gravimeter (C026) since 1996. We give the results of a tidal analysis performed with ETERNA on these data sets. We show the improvement in terms of noise levels from the oldest type to the newest one and check the time stability of the observed tides for every instrument. This stability is also dependent on the stability of the scale factor of the cryogenic Gravimeter which is derived from a direct comparison with repeated absolute gravity measurements. The response of the three Gravimeters to the atmospheric pressure changes is also checked. With all these results we found that the improvement from a mechanical spring Gravimeter to a modern cryogenic instrument is obvious. And also that the improvement from the T005 SG to the C026 SG is less impressive than from L&R to the T005 SG, but still notable.
Jeandaniel Bernard - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of a geothermal reservoir by hybrid gravimetry; feasibility study applied to the Soultz-sous-Forêts and Rittershoffen sites in the Rhine graben
Geothermal Energy, 2015Co-Authors: Jacques Hinderer, Yassine Abdelfettah, Basile Hector, Gilbert Ferhat, Marta Calvo, Umberto Riccardi, Jeandaniel BernardAbstract:The study is devoted to the monitoring of a geothermal reservoir by hybrid gravimetry combining different types of instruments (permanent superconducting Gravimeter, absolute ballistic Gravimeter, and micro-Gravimeters) and different techniques of measurements (both time-discrete and recording data collection). Using a micro-gravimetric repetition network around a reference station, which is regularly measured, leads to the knowledge of the time and space changes in surface gravity. Such changes can be linked to the natural or anthropic activities of the reservoir. A feasibility study using this methodology is applied to two geothermal sites in the Alsace region (France) of the Rhine graben. We show the results in terms of gravity double differences from weekly repetitions of a network of 11 stations around the geothermal reservoir of Soultz-sous-Forêts, separated into 5 loops during July–August 2013 and 2014 as well as preliminary results from 2 stations near Rittershoffen (ECOGI). We point out the importance of a precise leveling of the gravity points for the control of the vertical deformation. A first modeling of surface gravity changes induced by realistic geothermal density perturbations (Newtonian attraction) is computed in the frame of the existing geological model and leads to gravity changes below the μGal level being hence undetectable. However, and for the same case, borehole gravity modeling showed a significant anomaly with depth that can be used as a complementary monitoring method. We show that in the limit of our uncertainties (SD ~ 5 μGal), we do not detect any significant gravity change on the geothermal site of Soultz in agreement with the fact that there was indeed no geothermal activity during our analysis period. On the contrary, the measurements near Rittershoffen show a signal above the noise level which correlates in time with a production test but cannot be explained in terms of Newtonian attraction effects according to our basic numerical simulation.
Hilaire Legros - One of the best experts on this subject based on the ideXlab platform.
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Time stability of spring and superconducting Gravimeters through the analysis of very long gravity records
Journal of Geodynamics, 2014Co-Authors: Marta Calvo, Jacques Hinderer, Séverine Rosat, Hilaire Legros, Jean-paul Boy, Bernard Ducarme, Walter ZürnAbstract:Long gravity records are of great interest when performing tidal analyses. Indeed, long series enable to separate contributions of near-frequency waves and also to detect low frequency signals (e.g. long period tides and polar motion). In addition to the length of the series, the quality of the data and the temporal stability of the noise are also very important. We study in detail some of the longest gravity records available in Europe: 3 data sets recorded with spring Gravimeters in Black Forest Observatory (Germany, 1980-2012), Walferdange (Luxemburg, 1980-1995) and Potsdam (Germany, 1974-1998) and several superconducting Gravimeters (SGs) data sets, with at least 9 years of continuous records, at different European GGP (Global Geodynamics Project) sites (Bad Homburg, Brussels, Medicina, Membach, Moxa, Vienna, Wettzell and Strasbourg). The stability of each instrument is investigated using the temporal variations of tidal parameters (amplitude factor and phase difference) for the main tidal waves (O1, K1, M2 and S2) as well as the M2/O1 factor ratio, the later being insensitive to the instrumental calibration. The long term stability of the tidal observations is also dependent on the stability of the scale factor of the relative Gravimeters. Therefore we also check the time stability of the scale factor for the superconducting Gravimeter C026 installed at the J9 Gravimetric Observatory of Strasbourg (France), using numerous calibration experiments carried out by co-located absolute Gravimeter (AG) measurements during the last 15 years. The reproducibility of the scale factor and the achievable precision are investigated by comparing the results of different calibration campaigns. Finally we present a spectrum of the 25 years of SG records at J9 Observatory, with special attention to small amplitude tides in the semi-diurnal and diurnal bands, as well as to the low frequency part.
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Study of the Time Stability of Tides Using a Long Term (1973-2011) Gravity Record at Strasbourg, France
2014Co-Authors: Marta Calvo, Jacques Hinderer, J.-p. Boy, Séverine Rosat, Hilaire Legros, U. RiccardiAbstract:The Gravimetric Observatory J9 located near Strasbourg (France), has a long history of recording solid Earth tides. We present here one of the longest available gravity records (1973-2011) from three different instruments operating at the J9 station: a LaCoste-Romberg spring Gravimeter (ET005) from 1973 to 1985, a GWR (TT70-T005) superconducting Gravimeter from 1987 to 1996 and a GWR compact superconducting Gravimeter (C026) since 1996. We give the results of a tidal analysis performed with ETERNA on these data sets. We show the improvement in terms of noise levels from the oldest type to the newest one and check the time stability of the observed tides for every instrument. This stability is also dependent on the stability of the scale factor of the cryogenic Gravimeter which is derived from a direct comparison with repeated absolute gravity measurements. The response of the three Gravimeters to the atmospheric pressure changes is also checked. With all these results we found that the improvement from a mechanical spring Gravimeter to a modern cryogenic instrument is obvious. And also that the improvement from the T005 SG to the C026 SG is less impressive than from L&R to the T005 SG, but still notable.
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A simple method to retrieve the complex eigenfrequency of the Earth's nearly diurnal-free wobble; application to the Strasbourg superconducting Gravimeter data
Geophysical Journal International, 1994Co-Authors: Nicolas Florsch, Jacques Hinderer, Fréderic Chambat, Hilaire LegrosAbstract:We have analysed more than four years of data from the Strasbourg superconducting Gravimeter to retrieve the period and damping of the nearly diurnal-free wobble (NDFW). The removal of noise spikes is found to be crucial for an accurate determination of tidal-wave amplitudes and phases. A new simple algorithm is derived which allows an analytical solution for the NDFW pertod and damping using the complex gravimetric factors of three resonant diurnal waves. The results show a huge reduction of the confidence intervals when compared with a previous investigation from a Lacoste Romberg spring meter operated at the same station. Our results are in close agreement with values obtained from two other European superconducting Gravimeters. The results are also compared with respect to values inferred from very long baseline interferometry (VLBI) measurements.
