Le Laboratoire Souterrain de Géodynamique de Walferdange - Un joyau pour les sciences de la terre

Speeches/Talks (2009)

Relative Gravity Measurement Campaign during the 7th International Comparison of Absolute Gravimeters (2005)

in Metrologia (2009), 46(3), 214

Since the 1st International Comparison of Absolute Gravimeters (ICAG) and accompanying Relative Gravity Campaign (RGC) held at the BIPM in 1981, repeated ICAG-RGCs have been organized every four years. A ... [more ▼]

Since the 1st International Comparison of Absolute Gravimeters (ICAG) and accompanying Relative Gravity Campaign (RGC) held at the BIPM in 1981, repeated ICAG-RGCs have been organized every four years. A total of 19 absolute gravimeters (AG) and 15 relative gravimeters (RG) participated in the 7th ICAG-RGC, which took place in 2005. Co-located absolute and relative gravity measurements as well as precision levelling measurements were carried out. The final version of the absolute g values of the 7th ICAG has been officially released recently. This paper is the final report of the 7th RGC and replaces the preliminary results published earlier. It covers the organization of the RGC and the data processing, analyses RG behaviour, computes g , δ g and O AG (offset of AG) and discusses their uncertainties. In preparation for the BIPM key comparison ICAG-2009, a standard data-processing procedure has been developed and installed in the BIPM ICAG-RGC software package, GraviSoft. This was used for the final data processing. [less ▲]

New Devlopments in Gravity Applications and Instruments

Scientific Conference (2008, January 14)

Geodetic measurements of postglacial adjustments in Greenland

in Journal of Geophysical Research (2008)

We analyze data from seven continuous Global Positioning System (GPS) receivers and one tide gauge, all located along the edge of the Greenland ice sheet, to determine vertical uplift rates. We compare ... [more ▼]

We analyze data from seven continuous Global Positioning System (GPS) receivers and one tide gauge, all located along the edge of the Greenland ice sheet, to determine vertical uplift rates. We compare our results with predictions based on the ICE-5G deglaciation model of Peltier (2004). Results from the GPS receiver at Kellyville (-1.2 ± 1.1 mm/a) and from the tide gauge at Nuuk (-2.2 ± 1.3 mm/a), indicate that ICE-5G overestimates the subsidence rates at those locations by 2.1 and 1.1 mm/a, respectively. Kellyville and Nuuk are located along the southwestern margin of the Greenland ice sheet, and the observed negative uplift rates are consistent with independent evidence that the ice margin along the southwestern edge readvanced during the last ~8 ka to its current position. The ICE-5G glaciation-deglaciation history includes a readvance between the latitudes of 62°N and 72°N. The GPS measurements suggest the ICE-5G readvance may be too large or mistimed. Our GPS results at Qaqortoq, located at the southern tip of Greenland, suggest a secular subsidence rate of 􏰀0.3 ± 1.1 mm/a, while ICE-5G predicts an uplift rate of 1.0 mm/a. ICE-5G assumes no ice sheet readvance in south Greenland, including no readvance of the Qassimiut lobe. The difference of 1.3 ± 1.1 mm/a can tentatively be explained as due to a ~33 km readvance of the Qassimiut lobe during the last ~3 ka. For the other GPS sites, the observed/predicted uplift rates are 3.6 ± 1.1/-0.1 mm/a at Thule, 0.0 ± 1.1/2.0 mm/a at Scoresbysund, and -0.4 ± 1.1/-1.7 mm/a at Kulusuk. For Thule, Kulusuk, and Scoresbysund the differences between the observed and predicted rates are on the order of 1.3 – 3.7 mm/a, though with opposite signs, and indicate that ICE-5G does not exactly reproduce the correct rebound signal at those locations. [less ▲]

Absolute and Relative gravity Measurements in Qaqortoq (Greenland) in August 2007

Report (2007)

The Seventh International Comparison of Absolute Gravimeters ICAG-2005 at the BIPM. Organization and Preliminary reseults

in Kilicoglu, Ali; Forsberg, Rene (Eds.) Gravity Field of the Earth: Proceedings of the 1st International Symposium of the International Gravity Field Service (2007)

Is the instrumental drift of superconducting gravimeters a linear or exponential function of time?

in Journal of Geodesy (2007), 81(5), 337-344

Absolute and Relative Gravity Measurements at the Istituto Nazionale di Ricerca Metrologica (INRIM) of Turin (Italy) in June 2006

Report (2006)

Set standard deviation, repeatability and offset of absolute gravimeter A10-008

in Metrologia (2006), 43(5), 414

International Comparison of Absolute Gravimeters in Walferdange (Luxembourg) of November 2003

Book published by Centre Européen de Géodynamique et de Séismologie (2006)