Comparison of the Micro-g LaCoste gPhone-054 spring gravimeter and the GWR-C026 superconducting gravimeter in Strasbourg (France) using a 300-day time series

Metrologia ◽  
2011 ◽  
Vol 48 (1) ◽  
pp. 28-39 ◽  
Author(s):  
U Riccardi ◽  
S Rosat ◽  
J Hinderer
Keyword(s):  
Time Series ◽  
Superconducting Gravimeter ◽  
Spring Gravimeter

scholarly journals Determination of the complex frequencies for the normal modes below 1mHz after the 2010 Maule and 2011 Tohoku earthquakes

2014 ◽  
Vol 56 (5) ◽  
Author(s):  
Hao Ding ◽  
Wen-Bin Shen
Keyword(s):  
Time Series ◽  
Normal Modes ◽  
Power Spectra ◽  
Tohoku Earthquake ◽  
Superconducting Gravimeter ◽  
Width Ratio ◽  
Maule Earthquake ◽  
Attenuation Models ◽  
First Time

<p>Based upon SG (superconducting gravimeter) records, the autoregressive method proposed by Chao and Gilbert [1980] is used to determine the frequencies of the singlets of seven spheroidal modes (<sub>0</sub>S<sub>2</sub>, <sub>2</sub>S<sub>1</sub>, <sub>0</sub>S<sub>3</sub>, <sub>0</sub>S<sub>4</sub>, <sub>1</sub>S<sub>2</sub>, <sub>0</sub>S<sub>0</sub>, and <sub>3</sub>S<sub>1</sub>) and the degenerate frequencies of three toroidal modes (<sub>0</sub>T<sub>2</sub>, <sub>0</sub>T<sub>3</sub>, and <sub>0</sub>T<sub>4</sub>) below 1 mHz after two recent huge earthquakes, the 2010 Mw8.8 Maule earthquake and the 2011 Mw9.1 Tohoku earthquake. The corresponding quality factor <em>Q</em>s are also determined for those modes, of which the <em>Q</em>s of the five singlets of <sub>1</sub>S<sub>2</sub> and the five singlets (<em>m</em>=0, <em>m</em>=±2, and <em>m</em>=±3) of <sub>0</sub>S<sub>4</sub> are estimated for the first time using the SG observations. The singlet <em>m</em>=0 of <sub>3</sub>S<sub>1</sub> is clearly observed from the power spectra of the SG time series without using other special spectral analysis methods or special time series from pole station records. In addition, the splitting width ratio <em>R</em> of <sub>3</sub>S<sub>1</sub> is 0.99, and consequently we conclude that <sub>3</sub>S<sub>1</sub> is normally split. The frequencies and <em>Q</em>s of the modes below 1mHz may contribute to refining the 3D density and attenuation models of the Earth.</p>

scholarly journals Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure

2017 ◽  
Vol 21 (6) ◽  
pp. 3167-3182 ◽  
Author(s):  
Andreas Güntner ◽  
Marvin Reich ◽  
Michal Mikolaj ◽  
Benjamin Creutzfeldt ◽  
Stephan Schroeder ◽  
...  
Keyword(s):  
Time Series ◽  
Water Balance ◽  
Water Storage ◽  
Superconducting Gravimeter ◽  
Landscape Scale ◽  
Temperate Climate ◽  
Water Balance Components ◽  
Climate Conditions ◽  
The Road ◽  
Field Deployment

Abstract. In spite of the fundamental role of the landscape water balance for the Earth's water and energy cycles, monitoring the water balance and its components beyond the point scale is notoriously difficult due to the multitude of flow and storage processes and their spatial heterogeneity. Here, we present the first field deployment of an iGrav superconducting gravimeter (SG) in a minimized enclosure for long-term integrative monitoring of water storage changes. Results of the field SG on a grassland site under wet–temperate climate conditions were compared to data provided by a nearby SG located in the controlled environment of an observatory building. The field system proves to provide gravity time series that are similarly precise as those of the observatory SG. At the same time, the field SG is more sensitive to hydrological variations than the observatory SG. We demonstrate that the gravity variations observed by the field setup are almost independent of the depth below the terrain surface where water storage changes occur (contrary to SGs in buildings), and thus the field SG system directly observes the total water storage change, i.e., the water balance, in its surroundings in an integrative way. We provide a framework to single out the water balance components actual evapotranspiration and lateral subsurface discharge from the gravity time series on annual to daily timescales. With about 99 and 85 % of the gravity signal due to local water storage changes originating within a radius of 4000 and 200 m around the instrument, respectively, this setup paves the road towards gravimetry as a continuous hydrological field-monitoring technique at the landscape scale.

scholarly journals On the Chandler periodicity (Polar Motion, LOD and Climate)

2000 ◽  
Vol 178 ◽  
pp. 397-402
Author(s):  
F. Buffa ◽  
A. Poma
Keyword(s):  
Time Series ◽  
Polar Motion ◽  
Superconducting Gravimeter ◽  
Spin Axis ◽  
Rainfall Time Series ◽  
Observation Level ◽  
Motion Data ◽  
The Earth ◽  
Chandler Period ◽  
Free Nutation

AbstractThe 14-month Chandler period is associated with the free nutation of the Earth about its spin axis. The observed value of the Chandler period comes usually from the analysis of astronomical series of polar motion data as well as from superconducting gravimeter measurements. At the observation level a periodicity of about 420–440 days also was noticed in microseismic activities. Recently we found evidence of a signal with period similar to the Chandler one in the Sardinia rainfall time series.

scholarly journals Temporal variation of tidal parameters in superconducting gravimeter time-series

2016 ◽  
Vol 205 (1) ◽  
pp. 284-300 ◽  
Author(s):  
Bruno Meurers ◽  
Michel Van Camp ◽  
Olivier Francis ◽  
Vojtech Pálinkáš
Keyword(s):  
Time Series ◽  
Temporal Variation ◽  
Superconducting Gravimeter

scholarly journals Search for the 531 day-period wobble signal in the polar motion based on EEMD

2015 ◽  
Vol 2 (2) ◽  
pp. 647-673 ◽  
Author(s):  
H. Ding ◽  
W. B. Shen
Keyword(s):  
Time Series ◽  
Polar Motion ◽  
Superconducting Gravimeter ◽  
Ensemble Empirical Mode Decomposition ◽  
Stationary Time Series ◽  
Analysis Method ◽  
Intrinsic Mode Functions ◽  
Conventional Analysis ◽  
Mode Decomposition ◽  
Empirical Mode Decomposition Method

Abstract. In this study, we use a nonlinear and non-stationary time series analysis method, the ensemble empirical mode decomposition method (EEMD), to analyze the polar motion (PM) time series (EOP C04 series from 1962 to 2013) to find a 531 day-period wobble (531 dW) signal. The 531 dW signal has been found in the early PM seires (1962–1977) while cannot be found in the recent PM seires (1978–2013) using conventional analysis approaches. By the virtue of the demodulation feature of EEMD, the 531 dW can be confirmed to be present in PM based on the differences of the amplitudes and phases between different intrinsic mode functions. Results from three sub-series divided from the EOP C04 series show that the period of the 531 dW is subject to variations, in the range of 530.9–524 d, and its amplitude is also time-dependent (about 2–11 mas). Synthetic tests are carried out to explain why the 531 dW can only be observed in recent 30-years PM time series after using EEMD. The 531 dW is also detected in two longest available superconducting gravimeter (SG) records, which further confirms the presence of the 531 dW. The confirmation of 531 dW existence could be significant in establishing a more reasonable Earth rotation model and may effectively contribute to the prediction of the PM and its mechanism interpretation.

scholarly journals Exploring the use of a superconducting gravimeter to evaluate radar estimates of heavy rainfall

2018 ◽  
Author(s):  
Laurent Delobbe ◽  
Arnaud Watlet ◽  
Svenja Wilfert ◽  
Michel Van Camp
Keyword(s):  
Time Series ◽  
Spatial Scale ◽  
Correlation Coefficient ◽  
Superconducting Gravimeter ◽  
Interesting Property ◽  
Added Value ◽  
Absolute Difference ◽  
Rainfall Events ◽  
Gravity Measurements ◽  
Precipitation Estimates

Abstract. The radar-based estimation of intense precipitation produced by convective storms is a challenging task and the verification through comparison with gauges is questionable due to the very high spatial variability of such type of precipitation. In this study, we explore the potential benefit of using a superconducting gravimeter as a new source of in-situ observations for the evaluation of radar-based precipitation estimates. The superconducting gravimeter used in this study is installed in Membach (BE), 48 m underneath the surface, at 85 km distance from a C-band weather radar located in Wideumont (BE). The 15-year observation record 2003–2017 is available for both gravimeter and radar with 1-min and 5-min time steps, respectively. The gravimeter integrates soil water in a radius of about 400 m around the instrument. This allows capturing rainfall at larger spatial scale than traditional rain gauges. The precision of the gravimeter is a few nm/s2; 1 nm/s2 corresponding to 2.6 mm of water. The comparison of reflectivity and gravity time series for short duration intense rainfall events shows that reflectivity peaks larger than 40 dBZ are associated with a rapid decrease of the underground measured gravity. A remarkable correspondence between radar and gravimeter time series is found. The precipitation amounts derived from gravity measurements and from radar observations are further compared for 505 rainfall events. A correlation coefficient of 0.58, a mean bias (radar/gravimeter) of 1.24 and a mean absolute difference (MAD) of 3.19 mm are obtained. A better agreement is reached when applying a hail correction by truncating reflectivity values to a given threshold. No bias, a correlation coefficient of 0.64 and a MAD of 2.3 mm are reached using a 48-dBZ threshold. The added value of underground gravity measurements as verification dataset is discussed. The two main benefits are the spatial scale at which precipitation is captured and the interesting property that gravity measurements are directly influenced by water mass at ground no matter the type of precipitation: hail or rain.

scholarly journals Search for the 531-day-period wobble signal in the polar motion based on EEMD

2015 ◽  
Vol 22 (4) ◽  
pp. 473-484 ◽  
Author(s):  
H. Ding ◽  
W. Shen
Keyword(s):  
Time Series ◽  
Polar Motion ◽  
Superconducting Gravimeter ◽  
Ensemble Empirical Mode Decomposition ◽  
Stationary Time Series ◽  
Analysis Method ◽  
Intrinsic Mode Functions ◽  
Conventional Analysis ◽  
Mode Decomposition ◽  
Empirical Mode Decomposition Method

Abstract. In this study, we use a nonlinear and non-stationary time series analysis method, the ensemble empirical mode decomposition method (EEMD), to analyze the polar motion (PM) time series (EOP C04 series from 1962 to 2013) to find a 531-day-period wobble (531 dW) signal. The 531 dW signal has been found in the early PM series (1962–1977), but cannot be found in the recent PM series (1978–2013) using conventional analysis approaches. By virtue of the demodulation feature of EEMD, the 531 dW can be confirmed to be present in PM based on the differences of the amplitudes and phases between different intrinsic mode functions. Results from three sub-series divided from the EOP C04 series show that the period of the 531 dW is subject to variations, in the range of 530.9–524 days, and its amplitude is also time-dependent (about 2–11 mas). Synthetic tests are carried out to explain why the 531 dW can only be observed in recent 30-year PM time series after using EEMD. The 531 dW is also detected in the two longest available superconducting gravimeter (SG) records, which further confirms the presence of the 531 dW. The confirmation of the 531 dW existence could be significant in establishing a more reasonable Earth rotation model and may effectively contribute to the prediction of the PM and its mechanism interpretation.

Comparison between a six-year (2015-2020) continuous time series from an iGrav superconducting gravimeter and absolute gravity data at Mt. Etna volcano (Italy).

2021 ◽  
Author(s):  
Filippo Greco ◽  
Daniele Carbone ◽  
Alfio Alex Messina ◽  
Danilo Contrafatto
Keyword(s):  
Time Series ◽  
Continuous Time ◽  
Gravity Data ◽  
Total Error ◽  
Superconducting Gravimeter ◽  
Repeated Measurements ◽  
Absolute Gravity ◽  
Data Sets ◽  
Gravity Changes ◽  
Mt Etna

&lt;p&gt;Since September 2014, iGrav#016 superconducting gravimeter (SG; by GWR) has recorded continuously at the Serra La Nave Astrophysical Observatory (SLN; 1730 m elevation; ~6.5 km from the Etna&amp;#8217;s summit craters; Italy).&lt;/p&gt;&lt;p&gt;Here we present results of a comparison between a six-year (2015-2020) time series from iGrav#16 and absolute gravity data collected through the Microg LaCoste FG5#238 absolute gravimeter (AG), in the framework of repeated measurements that were performed at the same installation site of the SG. Both AG and SG records have been corrected for the local tides, local atmospheric pressure and for the polar motion effect.&lt;/p&gt;&lt;p&gt;The comparison allows to estimate the long-term drift of the SG, defined as the total SG trend minus the observed trend in AG measurements, which is of the order of 9 microGal/year. Once the drift effect is removed,&amp;#160; there is a remarkably good fit between the two data sets. The differences between absolute gravity changes and corresponding relative data in the continuous time series from the SG are within 1-2 microGal (the total error on AG measurements at this station is typically +/- 3 microGal).&lt;/p&gt;&lt;p&gt;After being corrected for the effect of instrumental drift, the time series from the SG reveals gravity changes that are due to hydrological and volcanological effects.&lt;/p&gt;&lt;p&gt;Our study shows how the combination of repeated AG measurements and continuous gravity observations through SGs can be used to obtain a fuller and more accurate picture of the temporal characteristics of the studied processes.&lt;/p&gt;

scholarly journals Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure

2017 ◽  
Author(s):  
Andreas Güntner ◽  
Marvin Reich ◽  
Michal Mikolaj ◽  
Benjamin Creutzfeldt ◽  
Stephan Schroeder ◽  
...  
Keyword(s):  
Time Series ◽  
Water Balance ◽  
Water Storage ◽  
Superconducting Gravimeter ◽  
Landscape Scale ◽  
Temperate Climate ◽  
Water Balance Components ◽  
Climate Conditions ◽  
The Road ◽  
Field Deployment

Abstract. In spite of the fundamental role of the landscape water balance for the Earth’s water and energy cycles, monitoring the water balance and its components beyond the point scale is notoriously difficult due to the multitude of flow and storage processes and their spatial heterogeneity. Here, we present the first field deployment of an iGrav superconducting gravimeter (SG) in a minimized enclosure for long-term integrative monitoring of water storage changes. Results of the field SG on a grassland site under wet-temperate climate conditions were compared to data provided by a nearby SG located in the controlled environment of an observatory building. The field system proves to provide gravity time series that are similarly precise as those of the observatory SG. At the same time, the field SG is more sensitive to hydrological variations than the observatory SG. We demonstrate that the gravity variations observed by the field setup are almost independent of the depth below the terrain surface where water storage changes occur (contrary to SGs in buildings), and thus the field SG system directly observes the total water storage change, i.e., the water balance, in its surroundings in an integrative way. We provide a framework to single out the water balance components actual evapotranspiration and lateral subsurface discharge from the gravity time series on annual to daily time scales. With about 99 % and 85 % of the gravity signal due to local water storage changes originating within a radius of 4000 and 200 meter around the instrument, respectively, this setup paves the road towards gravimetry as a continuous hydrological field monitoring technique at the landscape scale.

scholarly journals Exploring the use of underground gravity monitoring to evaluate radar estimates of heavy rainfall

2019 ◽  
Vol 23 (1) ◽  
pp. 93-105 ◽  
Author(s):  
Laurent Delobbe ◽  
Arnaud Watlet ◽  
Svenja Wilfert ◽  
Michel Van Camp
Keyword(s):  
Time Series ◽  
Spatial Scale ◽  
Correlation Coefficient ◽  
Water Mass ◽  
Superconducting Gravimeter ◽  
Interesting Property ◽  
Added Value ◽  
Absolute Difference ◽  
Rainfall Events ◽  
Gravity Measurements

Abstract. The radar-based estimation of intense precipitation produced by convective storms is a challenging task and the verification through comparison with gauges is questionable due to the very high spatial variability of such types of precipitation. In this study, we explore the potential benefit of using a superconducting gravimeter as a new source of in situ observations for the evaluation of radar-based precipitation estimates. The superconducting gravimeter used in this study is installed in Membach (BE), 48 m underneath the surface, at 85 km distance from a C-band weather radar located in Wideumont (BE). The 15-year observation record 2003–2017 is available for both gravimeter and radar with 1 and 5 min time steps, respectively. Water mass increase at ground due to precipitation results in a decrease in underground measured gravity. The gravimeter integrates soil water in a radius of about 400 m around the instrument. This allows capture of rainfall at a larger spatial scale than traditional rain gauges. The precision of the gravimeter is a few tenths of nm s−2, 1 nm s−2 corresponding to 2.6 mm of water. The comparison of reflectivity and gravity time series shows that short-duration intense rainfall events produce a rapid decrease in the underground measured gravity. A remarkable correspondence between radar and gravimeter time series is found. The precipitation amounts derived from gravity measurements and from radar observations are further compared for 505 rainfall events. A correlation coefficient of 0.58, a mean bias (radar–gravimeter)/gravimeter of 0.24 and a mean absolute difference (MAD) of 3.19 mm are obtained. A better agreement is reached when applying a hail correction by truncating reflectivity values to a given threshold. No bias, a correlation coefficient of 0.64 and a MAD of 2.3 mm are reached using a 48 dBZ threshold. The added value of underground gravity measurements as a verification dataset is discussed. The two main benefits are the spatial scale at which precipitation is captured and the interesting property that gravity measurements are directly influenced by water mass at ground no matter the type of precipitation: hail or rain.

Sign in / Sign up

Export Citation Format

Share Document