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See detailBedrock displacements in Greenland manifest ice mass variations, climate cycles and climate change
Bevis, Michael; Wahr, John; Khan, Shfaqat A. et al

in Proceedings of the National Academy of Sciences of the United States of America (2012), 109(30), 11944-11948

The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. The entire network is uplifting in ... [more ▼]

The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. The entire network is uplifting in response to past and present-day changes in ice mass. Crustal displacement is largely accounted for by an annual oscillation superimposed on a sustained trend. The oscillation is driven by earth’s elastic response to seasonal variations in ice mass and air mass (i.e., atmospheric pressure). Observed vertical velocities are higher and often much higher than predicted rates of postglacial rebound (PGR), implying that uplift is usually dominated by the solid earth’s instantaneous elastic response to contemporary losses in ice mass rather than PGR. Superimposed on longer-term trends, an anomalous ‘pulse’ of uplift accumulated at many GNET stations during an approximate six-month period in 2010. This anomalous uplift is spatially correlated with the 2010 melting day anomaly. [less ▲]

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See detailThe 8th International Comparison of Absolute Gravimeters 2009: the first Key Comparison (CCM.G-K1) in the field of absolute gravimetry
Jiang, Z.; Pálinkáš, V.; Arias, F. E. et al

in Metrologia (2012), 49(6), 666

The 8th International Comparison of Absolute Gravimeters (ICAG2009) took place at the headquarters of the International Bureau of Weights and Measures (BIPM) from September to October 2009. It was the ... [more ▼]

The 8th International Comparison of Absolute Gravimeters (ICAG2009) took place at the headquarters of the International Bureau of Weights and Measures (BIPM) from September to October 2009. It was the first ICAG organized as a key comparison in the framework of the CIPM Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA) (CIPM 1999). ICAG2009 was composed of a Key Comparison (KC) as defined by the CIPM MRA, organized by the Consultative Committee for Mass and Related Quantities (CCM) and designated as CCM.G-K1. Participating gravimeters and their operators came from national metrology institutes (NMIs) or their designated institutes (DIs) as defined by the CIPM MRA. A Pilot Study (PS) was run in parallel in order to include gravimeters and their operators from other institutes which, while not signatories of the CIPM MRA, nevertheless play important roles in international gravimetry measurements. The aim of the CIPM MRA is to have international acceptance of the measurement capabilities of the participating institutes in various fields of metrology. The results of CCM.G-K1 thus constitute an accurate and consistent gravity reference traceable to the SI (International System of Units), which can be used as the global basis for geodetic, geophysical and metrological observations of gravity. The measurements performed afterwards by the KC participants can be referred to the international metrological reference, i.e. they are SI-traceable. The ICAG2009 was complemented by a number of associated measurements: the Relative Gravity Campaign (RGC2009), high-precision levelling and an accurate gravity survey in support of the BIPM watt balance project. The major measurements took place at the BIPM between July and October 2009. Altogether 24 institutes with 22 absolute gravimeters (one of the 22 AGs was ultimately withdrawn) and nine relative gravimeters participated in the ICAG/RGC campaign. This paper is focused on the absolute gravity campaign. We review the history of the ICAGs and present the organization, data processing and the final results of the ICAG2009. After almost thirty years of hosting eight successive ICAGs, the CIPM decided to transfer the responsibility for piloting the future ICAGs to NMIs, although maintaining a supervisory role through its Consultative Committee for Mass and Related Quantities. [less ▲]

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See detailFinal report of the regional key comparison EURAMET.M.G-K1: European Comparison of Absolute Gravimeters ECAG-2011
Francis, Olivier UL; Klein, Gilbert UL; Baumann, Henri et al

in Metrologia (2012), 49(1A), 07014

During November 2011 a EURAMET key comparison of absolute gravimeters was organized in the Underground Laboratory for Geodynamics in Walferdange, Luxemburg. The comparison assembled 22 participants coming ... [more ▼]

During November 2011 a EURAMET key comparison of absolute gravimeters was organized in the Underground Laboratory for Geodynamics in Walferdange, Luxemburg. The comparison assembled 22 participants coming from 16 countries and four different continents. The comparison was divided into two parts: a key comparison that included six National Metrology Institutes or Designated Institutes, and a pilot study including all participants. The global result given by the pilot study confirms that all instruments are absolutely coherent with each other. The results obtained in the key comparison confirm a good agreement between the NMI instruments. Finally, a link to ICAG-2009 [http://iopscience.iop.org/0026-1394/49/1A/07011/] shows also that the NMI gravimeters are stable in time. Main text. To reach the main text of this paper, click on Final Report [http://www.bipm.org/utils/common/pdf/final_reports/M/G-K1/EURAMET.M.G-K1.pdf] . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ [http://kcdb.bipm.org/] . The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA). [less ▲]

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See detailComparison between the Transfer Functions of three Superconducting Gravimeters
Francis, Olivier UL; Lampitelli, Carmine UL; Klein, Gilbert UL et al

in Marées Terrestres Bulletin d'Informations (2011), 147

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See detailSecond-order Doppler-shift corrections in free-fall absolute gravimeters
Rothleitner, Christian UL; Francis, Olivier UL

in Metrologia (2011), 48(3), 187-195

In a free-fall absolute gravimeter usually a Michelson type interferometer is employed to track the trajectory of a freely falling retroreflector. The accelerated motion of the retroreflector produces a ... [more ▼]

In a free-fall absolute gravimeter usually a Michelson type interferometer is employed to track the trajectory of a freely falling retroreflector. The accelerated motion of the retroreflector produces a Doppler-shift in the laser wavelength. From the interference signal (beat signal) of the Doppler-shifted and the reference electromagnetic waves the relative motion of the freely falling retroreflector with respect to an inertial reference retroreflector is reconstructed. Considerations of second-order Doppler-shift terms lead to a correction in the acceleration due to gravity of several microgals (1 µGal = 10 nm s −2 ). This correction is commonly called speed of light correction . To date different correction formulae have been proposed, which differ by several microgals. In this paper we review several previous publications and show the reasons for the different results. [less ▲]

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See detailRevisiting absolute gravimeter intercomparisons
de Viron, O.; Van Camp, Michel; Francis, Olivier UL

in Metrologia (2011), 48

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See detailMonitoring Earthquakes with gravity meters
Niebauer, T. M.; MacQueen, Jeff; Aliod, Daniel et al

in Geodesy and Geodynamics (2011), 2(3), 71-75

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See detailPreliminary results of the BIPM Relative Gravity Measurement Campaign during the 8th International Comparison of Absolute Gravimeters (2009)
Jiang, Zihang; Tisserand, L.; Kessler-Schulz, K. U. et al

in Peshekhonov, Vladimir (Ed.) Proceedings of the IAG Symposium on Terrestrial Gravimetry: Static and Mobile Measurements (2011)

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See detailFinal report on the Seventh International Comparison of Absolute Gravimeters (ICAG 2005)
Jiang, Z.; Francis, Olivier UL; Vitushkin, L. et al

in Metrologia (2011), 48

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See detailEarthquake Monitoring with Gravity Meters: Case studies from the November 2006 and January 2007 Kuril Islands Earthquakes
Niebauer, T.M.; Hare, J.L.; MacQueen, J. et al

Scientific Conference (2010, August 15)

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See detailSimultaneous observation of gravity tide in Juneau, Southeast Alaska with gPhone#32 and L&R G578 gravimeters
Sato, T.; Miura, S.; Ohta, Y. et al

Speeches/Talks (2010)

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See detailOn the influence of the rotation of a corner cube reflector in absolute gravimetry
Rothleitner, Christian UL; Francis, Olivier UL

in Metrologia (2010), 47(5), 567

Test masses of absolute gravimeters contain prism or hollow retroreflectors. A rotation of such a retroreflector during free-fall can cause a bias in the measured g -value. In particular, prism ... [more ▼]

Test masses of absolute gravimeters contain prism or hollow retroreflectors. A rotation of such a retroreflector during free-fall can cause a bias in the measured g -value. In particular, prism retroreflectors produce phase shifts, which cannot be eliminated. Such an error is small if the rotation occurs about the optical centre of the retroreflector; however, under certain initial conditions the error can reach the microgal level. The contribution from these rotation-induced accelerations is calculated. [less ▲]

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See detailFinal report on absolute gravimeter intercomparison (EURAMET Project no. 1093)
Baumann, Henri; Francis, Olivier UL; Van Camp, Michel

in Metrologia (2010), 47(1A), 07008

An interlaboratory comparison (Euramet Project 1039) of three absolute gravimeters was carried out between the national metrology institutes of Luxembourg, Belgium and Switzerland (University of ... [more ▼]

An interlaboratory comparison (Euramet Project 1039) of three absolute gravimeters was carried out between the national metrology institutes of Luxembourg, Belgium and Switzerland (University of Luxembourg/ECGS, Royal Observatory of Belgium and Federal Office for Metrology METAS). The comparison was hosted in the Underground Laboratory for Geodynamics in Walferdange. The obtained results confirm a perfect agreement between the instruments used with respective expanded uncertainties ( k = 2) of 4.25 µGal. Finally, a link to the Euramet project 1030 shows that the three gravimeters are coherent with the 19 other gravimeters. Main text. To reach the main text of this paper, click on Final Report [http://www.bipm.org/utils/common/pdf/final_reports/M/G-S1/EURAMET.M.G-S1.pdf] . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ [http://kcdb.bipm.org/] . The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA). [less ▲]

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See detailResults of the Seventh International Comparison of Absolute Gravimeters ICAG-2005 at the Bureau International des Poids et Mesures, Sèvres
Vitushkin, L.; Jiang, Z.; Robertsson, L. et al

in Mertikas, Stelios P. (Ed.) Gravity, Geoid and Earth Observation (2010)

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See detailResults of the European Comparison of Absolute Gravimeters in Walferdange (Luxembourg) of November 2007
Francis, Olivier UL; van Dam, Tonie UL; Germak, A. et al

in Gravity, Geoid and Earth Observation (2010)

The second international comparison of absolute gravimeters was held in Walferdange, Grand Duchy of Luxembourg, in November 2007, in which twenty absolute gravimeters took part. A short description of the ... [more ▼]

The second international comparison of absolute gravimeters was held in Walferdange, Grand Duchy of Luxembourg, in November 2007, in which twenty absolute gravimeters took part. A short description of the data processing and adjustments will be presented here and will be followed by the presentation of the results. Two different methods were applied to estimate the relative offsets between the gravimeters. We show that the results are equivalent as the uncertainties of both adjustments overlap. The absolute gravity meters agree with one another with a standard deviation of 2 μgal (1 gal = 1 cm/s2). [less ▲]

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See detail欧洲绝对重力仪比对观测 (ECGS’07)
邢乐林; 申重阳; 李辉 et al

in 地球物理学进展 (Progress in Geophysics) (2009), 24(6), 2054-2057

Detailed reference viewed: 89 (6 UL)