scholarly journals The Contribution of GGP Superconducting Gravimeters to GGOS

2008 ◽  
pp. 841-852 ◽  
Author(s):  
David Crossley ◽  
Jacques Hinderer
Keyword(s):  
Superconducting Gravimeters

Extracting Long-Period Surface Waves and Free Oscillations Using Ambient Noise Recorded by Global Distributed Superconducting Gravimeters

2020 ◽  
Vol 91 (4) ◽  
pp. 2234-2246
Author(s):  
Hang Li ◽  
Jianqiao Xu ◽  
Xiaodong Chen ◽  
Heping Sun ◽  
Miaomiao Zhang ◽  
...  
Keyword(s):  
Surface Waves ◽  
Group Velocity ◽  
Ambient Noise ◽  
Velocity Dispersion ◽  
Group Velocity Dispersion ◽  
Dispersion Curves ◽  
Free Oscillations ◽  
Long Period ◽  
Superconducting Gravimeters ◽  
Noise Data

Abstract Inversion of internal structure of the Earth using surface waves and free oscillations is a hot topic in seismological research nowadays. With the ambient noise data on seismically quiet days sourced from the gravity tidal observations of seven global distributed superconducting gravimeters (SGs) and the seismic observations for validation from three collocated STS-1 seismometers, long-period surface waves and background free oscillations are successfully extracted by the phase autocorrelation (PAC) method, respectively. Group-velocity dispersion curves at the frequency band of 2–7.5 mHz are extracted and compared with the theoretical values calculated with the preliminary reference Earth model. The comparison shows that the best observed values differ about ±2% from the corresponding theoretical results, and the extracted group velocities of the best SG are consistent with the result of the collocated STS-1 seismometer. The results indicate that reliable group-velocity dispersion curves can be measured with the ambient noise data from SGs. Furthermore, the fundamental frequency spherical free oscillations of 2–7 mHz are also clearly extracted using the same ambient noise data. The results in this study show that the SG, besides the seismometer, is proved to be another kind of instrument that can be used to observe long-period surface waves and free oscillations on seismically quiet days with a high degree of precision using the PAC method. It is worth mentioning that the PAC method is first and successfully introduced to analyze SG observations in our study.

scholarly journals Estimation of free core resonance parameters based on long-term strain observations in the diurnal frequency band

2019 ◽  
pp. 41-50
Author(s):  
V. K. Milyukov ◽  
A. Amoruso ◽  
L. Crescentini ◽  
A. P. Mironov ◽  
A. V. Myasnikov ◽  
...  
Keyword(s):  
Laser Interferometer ◽  
Liquid Core ◽  
Resonant Mode ◽  
Parameter Estimates ◽  
Retrograde Motion ◽  
Tidal Waves ◽  
Superconducting Gravimeters ◽  
Fixed Reference ◽  
Free Core Resonance

The free core nutation (FCN) is one of the Earth’s rotational eigenmodes, which is caused by the retrograde motion of the liquid core relative to the mantle. The FCN period and Q-factor are determined by the elastic properties of the core/mantle boundary (CMB) and their electromagnetic interaction. In the celestial coordinate system, the FCN period is about 430 days; in the Earth-fixed reference frame this effect manifests itself in the form of the free core resonance (FCR) whose frequency falls in the diurnal tidal band. FCR observation requires highly accurate measurement of the amplitudes and phases of the near-diurnal tidal waves. In particular, the parameter estimates for minor waves K1, P1, Ψ1, and Φ1 are critically important for evaluating the FCR effect, i.e., the period and decay of this resonant mode. The progress in the experimental study of FCR is mainly due to the accumulation of the data from superconducting gravimeters and VLBI; at the same time, also the data of the precision laser strainmeters were used. In this work, the FCR effect is studied based on the long-term strain precision records by two European stations: Baksan, Russia (laser interferometer–strainmeter with a measuring armlength of 75 m [Milyukov et al., 2005; 2007] and Gran Sasso, Italy (two perpendicular laser interferometer–strainmeters, BA and BC, each with a measuring armlength of 90 m [Amoruso and Crescentini, 2009]).

Seasonal changes in the European gravity field from GRACE: A comparison with superconducting gravimeters and hydrology model predictions

2006 ◽  
Vol 41 (1-3) ◽  
pp. 59-68 ◽  
Author(s):  
Jacques Hinderer ◽  
Ole Andersen ◽  
Frank Lemoine ◽  
David Crossley ◽  
Jean-Paul Boy
Keyword(s):  
Gravity Field ◽  
Seasonal Changes ◽  
Superconducting Gravimeters ◽  
Model Predictions ◽  
Hydrology Model

scholarly journals Limits on Lorentz violation in gravity from worldwide superconducting gravimeters

2018 ◽  
Vol 97 (2) ◽  
Author(s):  
Cheng-Gang Shao ◽  
Ya-Fen Chen ◽  
Rong Sun ◽  
Lu-Shuai Cao ◽  
Min-Kang Zhou ◽  
...  
Keyword(s):  
Lorentz Violation ◽  
Superconducting Gravimeters

Deploying and operating an Absolute Quantum Gravimeter on the summit of Mount Etna volcano

2021 ◽  
Author(s):  
Daniele Carbone ◽  
Laura Antoni-Micollier ◽  
Filippo Greco ◽  
Jean Lautier-Gaud ◽  
Danilo Contrafatto ◽  
...  
Keyword(s):  
Gravity Data ◽  
Volcanic Tremor ◽  
Mount Etna ◽  
Quality Data ◽  
Etna Volcano ◽  
High Quality ◽  
Absolute Gravimetry ◽  
Superconducting Gravimeters ◽  
Mt Etna ◽  
Absolute Quantum

<p>The NEWTON-g project [1] proposes a paradigm shift in terrain gravimetry to overcome the limitations imposed by currently available instrumentation. The project targets the development of an innovative gravity imager and the field-test of the new instrumentation through the deployment at Mount Etna volcano (Italy). The gravity imager consists in an array of MEMS-based relative gravimeters anchored on an Absolute Quantum Gravimeter [2].<br>The Absolute Quantum Gravimeter (AQG) is an industry-grade gravimeter measuring g with laser-cooled atoms [3]. Within the NEWTON-g project, an enhanced version of the AQG (AQGB03) has been developed, which is able to produce high-quality data against strong volcanic tremor at the installation site.<br>After reviewing the key principles of the AQG, we present the deployment of the AQGB03 at the Pizzi Deneri (PDN) Volcanological Observatory (North flank of Mt. Etna; 2800 m elevation; 2.5 km from the summit active craters), which was completed in summer 2020. We then show the demonstrated measurement performances of the AQG, in terms of sensitivity and stability. In particular, we report on a reproducible sensitivity to gravity at a level of 1 μGal, even during intense volcanic activity.<br>We also discuss how the time series acquired by AQGB03 at PDN compares with measurements from superconducting gravimeters already installed at Mount Etna. In particular, the significant  correlation with gravity data collected at sites 5 to 9 km away from PDN proves that effects due to bulk mass sources, likely related to volcanic processes, are predominant over possible local and/or instrumental artifacts.<br>This work demonstrates the feasibility to operate a free-falling quantum gravimeter in the field, both as a transportable turn-key device and as a drift-free monitoring device, able to provide high-quality continuous measurements under harsh environmental conditions. It paves the way to a wider use of absolute gravimetry for geophysical monitoring.</p><p>[1] www.newton-g.com</p><p>[2] D. Carbone et al., “The NEWTON-g Gravity Imager: Toward New Paradigms for Terrain Gravimetry”, Front. Earth Sci. 8:573396 (2020)</p><p>[3] V. Ménoret et al., "Gravity measurements below 10−9 g with a transportable absolute quantum gravimeter", Nature Scientific Reports, vol. 8, 12300 (2018)</p>

A novel Nb superconducting joint with ultralow resistance fabricated by electron beam welding method for superconducting gravimeter

2021 ◽  
Author(s):  
Zili Zhang ◽  
Xing Huang ◽  
Chunyan Cui ◽  
Hao Wang ◽  
Feifei Niu ◽  
...  
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Structural Geology ◽  
Drift Rate ◽  
Electron Beam Welding ◽  
Superconducting Gravimeter ◽  
Superconducting Gravimeters ◽  
Maximum Stability ◽  
Grain Misorientation ◽  
Low Drift

Abstract This paper presents a novel Nb superconducting joint with an ultralow resistance of 7.9 × 10-16 Ω, fabricated using the electron beam welding (EBW) method. After the EBW process, the two Nb filaments formed a single joint with a much larger grain size and smaller grain misorientation. More importantly, the resistance of the EBW Nb joint was nearly one magnitude lower than that of most conventional pressing joint. The ultralow resistance is essential for superconducting gravimeters, which require an extremely low drift rate. The EBW Nb joint allowed the superconducting gravimeter to have a much better performance when applied in the field of structural geology, geodesy, microgravity, and metrology. We believe that the EBW method could be one of the most promising joint fabrication methods for achieving maximum stability (less than 1 μgal/yr).

scholarly journals Low-degree toroidal modes from the Sumatra-Andaman event observed by superconducting gravimeters

2019 ◽  
Vol 10 (6) ◽  
pp. 477-484
Author(s):  
Chuang Xu ◽  
Hangtao Yu ◽  
Guangyu Jian ◽  
Shiqi Deng ◽  
Boyang Zhou ◽  
...  
Keyword(s):  
Low Degree ◽  
Superconducting Gravimeters

scholarly journals MicroGal Gravity Measurements with MGS-6 Micro-g LaCoste Gravimeter

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2592 ◽  
Author(s):  
Marek Przyborski ◽  
Jerzy Pyrchla ◽  
Krzysztof Pyrchla ◽  
Jakub Szulwic
Keyword(s):  
Temporal Stability ◽  
Low Noise ◽  
Reference Source ◽  
Time Stability ◽  
Superconducting Gravimeters ◽  
Gravity Measurements ◽  
Gravity Sensor ◽  
The Impact ◽  
Micro Gravity

The article discusses the registration of micro-gravity changes with the MGS-6 Micro-g LaCoste gravity sensor during static measurements. An experiment was carried out to determine how small changes in gravity can be registered using the MGS-6 system sensor. The tides of the Earth’s crust were chosen as the source of disturbance of the field with small amplitude and long-term changes. The tested sensor was placed in a geophysical observatory on a specially designed tripod. Simultaneously on the nearby concrete pillar, the registration of changes in gravity was carried out using the superconducting iGrav gravimeter. The high temporal stability of the superconducting gravimeters and the low noise combined with leading sensitivity of its reading allow it to be considered as a reliable reference source for MGS-6. The article discusses the impact of non-leveling changes of the MGS-6 gravimetry on the reading and determines the size of its non-linear drift. The obtained differences in indications between devices did not exceed 50 μ Gal for 68% of data. The measurements also showed excellent time stability of the MGS-6 measurement system. The data collected during the experiment allowed determining the level of accuracy that can be sought during real measurements using the MGS-6 system on research vessels. They also give an overview of the dynamics of the drift phenomenon of the analyzed research system.

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