References of "Francis, Olivier 50001803"
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See detailGPS measurements of vertical crustal motion in Greenland
Wahr, John; van Dam, Tonie UL; Larson, Kristine et al

in Journal of Geophysical Research (2001), 106(D24), 33755-33759

We have analyzed 5 years of continuous Global Positioning System (GPS) measurements taken at Kellyville, just off the western margin of the ice sheet in southern Greenland. A fit to the vertical component ... [more ▼]

We have analyzed 5 years of continuous Global Positioning System (GPS) measurements taken at Kellyville, just off the western margin of the ice sheet in southern Greenland. A fit to the vertical component gives a negative secular uplift rate of −5.8±1.0 mm/yr. A negative rate (i.e., a subsidence) is consistent with archeological and historical evidence that the surrounding region has been subsiding over the last 3 kyr. However, it is inconsistent with estimates of the Earth's continuing viscoelastic response to melting ice prior to 4 ka years ago, which predict that Kellyville should be uplifting, rather than subsiding, by 2.0±3.5 mm/yr. The resulting −7.8±3.6 mm/yr discrepancy is too large to be the result of loading from present-day changes in nearby ice. We show, instead, that it is consistent with independent suggestions that the western ice sheet margin in this region of Greenland may have advanced by ≈50 km during the past 3–4 kyr. [less ▲]

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See detailGlobal Positioning System and Gravity Used to Study Greenland Ice
van Dam, Tonie UL; Larson, Kristine; Wahr, John et al

in Earth in Space (2001), 13(5), 1-16

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See detailGeodetic measurements in Greenland and their implications
Wahr, John; van Dam, Tonie UL; Larson, Kristine et al

in Journal of Geophysical Research (2001), 106(B8), 16567-16581

We describe results from an ongoing experiment in Greenland, in which we are using absolute gravity and continuous Global Positioning System (GPS) measurements to study vertical crustal motion at two ... [more ▼]

We describe results from an ongoing experiment in Greenland, in which we are using absolute gravity and continuous Global Positioning System (GPS) measurements to study vertical crustal motion at two locations along the edge of the ice sheet: Kellyville, located about one third of the way up the western ice margin, and Kulusuk, located along the eastern ice margin at about the same latitude as Kellyville. The GPS measurements suggest average crustal uplift rates of -5.8±1.0 mm/yr at Kellyville and -2.1±1.5 mm/yr at Kulusuk. There have not yet been enough absolute gravity occupations to permit useful secular gravity solutions at either location. The negative uplift rate at Kellyville is consistent with independent archeological and historical evidence that the southwestern edge of the continent has been subsiding over the last 3000 years, but it is inconsistent with estimates of the Earth's continuing viscoelastic response to melting ice during the early Holocene, which predict that Kellyville is likely to be uplifting, rather than subsiding, by 2.0±3.5 mm/yr. The resulting -7.8±3.6 mm/yr discrepancy between the observed and predicted uplift rates is too large to be caused by loading from present-day changes in nearby ice. However, it is consistent with independent suggestions that the western ice sheet margin in this region may have advanced by ≈50 km during the past 3000-4000 years. If this advance did occur and if the crustal subsidence it induces is not removed from altimeter measurements of Greenland ice sheet elevations, then the altimeter solutions could underestimate the true snow/ice thickness change by 5-10 mm/yr along portions of the western margin of the ice sheet. [less ▲]

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See detailResults from the Fifth Internationl Comparison of Absolute Gravimeters, ICAG97
Robertsson, L.; Francis, Olivier UL; van Dam, Tonie UL et al

in Metrologia (2001), 38

The fifth in the series of International Comparisons of Absolute Gravimeters (ICAG) was held at the Bureau International des Poids et Measures (BIPM) in November 1997. Fifteen absolute gravimeters ... [more ▼]

The fifth in the series of International Comparisons of Absolute Gravimeters (ICAG) was held at the Bureau International des Poids et Measures (BIPM) in November 1997. Fifteen absolute gravimeters participated in the comparison. The mean gravity value obtained at station A (0.9 m) at the BIPM was found to be 980 925 707.8 µGal with a standard uncertainty of 2.8 µGal. This is consistent with the results obtained in previous comparisons at this site. Conclusions based on the analysis of the present results and proposals for future activities are presented. [less ▲]

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See detailBeyond Tides - Determination of Core Properties from Superconducting Gravimeter Observations
Smylie, Douglas E.; Francis, Olivier UL; Merriam, James B.

in Journal of the Geodetic Society of Japan (2001), 47(1), 364-372

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See detailCore Properties from Superconducting Gravimeter Data
Smylie; Francis, Olivier UL; Henderson, Gary

in Romanowicz, Barbara; Suyehiro, Kiyoshiro (Eds.) Long-term Observations in the Oceans - Current Status and Perspectives for the Future (2001)

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See detailGravity Changes due to Continental Water Storage
van Dam, Tonie UL; Wahr, John M.; Milly, P. Chris D. et al

in Journal of the Geodetic Society of Japan (2001), 47(1), 249-254

Five years of global continental water storage variations are used to predict the effects of long-wavelength, long-period variability in water storage on gravity observations. At the sites of existing ... [more ▼]

Five years of global continental water storage variations are used to predict the effects of long-wavelength, long-period variability in water storage on gravity observations. At the sites of existing superconducting gravimeters, the modeled gravity changes have root-mean-square (RMS) values of as much as 7 mu Gals, with ranges of up to 22 mu Gals. Variations much larger than these values can be found over large regions the globe. We find that the gravity effects are predominantly annual in character. We also find that the modeled responses to water loading exhibit long-period variations that could be mistaken for secular tectonic trends when observed over a time span of a few years. [less ▲]

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See detailCalibration of the LaCoste-Romberg 906 by Comparison with the Superconducting Gavimeter C021 in Membach (Belgium)
Francis, Olivier UL; Hendrickx, Marc

in Journal of the Geodetic Society of Japan = Sokuchi-Gakkai-shi (2001), 47(1), 16-21

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See detailAccurate transfer function determination for superconducting gravimeters
Van Camp, Michel; Wenzel, H.-G.; Schott, P. et al

in Geophysical Research Letters (2000), 27(1), 37-40

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See detailUsing GPS and Gravity to Infer Ice Mass Changes in Greenland
van Dam, Tonie UL; Larson, Kristine; Wahr, John et al

in EOS : Transactions, American Geophysical Union (2000), 81(37), 421-427

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See detailAn International Reference Station for Inter-comparison of Absolute Gravimeters (ISIAG) in Walferdange, Luxembourg: The GRAVILUX Project
D'OREYE, N.; van Dam, Tonie UL; Francis, Olivier UL

in Bulletin d'Information du Bureau Gravimétrique International (2000), (86), 27-36

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See detailResults of relative gravimeter measurements at the ICAG97 intercomparison
Becker, M.; Berrino, G.; Camacho, A. G. et al

in Bulletin d'information du Bureau Gravimétrique International (2000), (85), 61-72

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See detailIntercomparison between the FG5 202 and FGG 206 at the site of the superconducting gravimeter C021 in Membach (Belgium)
Francis, Olivier UL; Amalvict, M.; Hinderer, J.

in Bulletin d'Information du Bureau Gravimétrique International (1999), (84), 36-39

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See detailNetwork of Superconducting Gravimeters Benefits a Number of Disciplines
Crossley, D.; Hinderer, J.; Casula, G. et al

in EOS : Transactions, American Geophysical Union (1999), 80(11), 121-126

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See detailOn the calibration of superconducting gravimeters with the help of absolute gravity measurements
Hinderer, Jacques; Amalvict, Martine; Florsch, Nicolas et al

in Ducarme, Bernard; Pâquet, Paul (Eds.) Proceedings of the Thirteenth International Symposium on Earth Tides (1998)

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See detailComparisons between Absolute (AG) and Superconducting (SG) Gravimeters
Amalvict, Martine; Hinderer, Jacques; Francis, Olivier UL et al

in Forsberg, Rene; Feissel, Martine; Dietrich, Reinhard (Eds.) Geodesy on the Move (1998)

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See detailTwo years of continuous measurements of tidal and nontidal variations of gravity in Boulder, Colorado
van Dam, Tonie UL; Francis, Olivier UL

in Geophysical Research Letters (1998), 25(3), 393-396

We report here on the results of an analysis of 2 years of data from NOAA’s superconducting gravimeter located at the Table Mountain Gravity Observatory in Boulder, Colorado. Observed tidal parameters ... [more ▼]

We report here on the results of an analysis of 2 years of data from NOAA’s superconducting gravimeter located at the Table Mountain Gravity Observatory in Boulder, Colorado. Observed tidal parameters, corrected for ocean loading effects, are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate excellent agreement. Tidal residuals, corrected for polar motion and a linear instrument drift are highly correlated with gravity changes measured by two absolute gravimeters over the same time period. The admittance to local pressure i s found to be -0.356 mGal/mbar. However, this admittance factor is found to be seasonally and frequency dependent. Correlations between rainfall events and gravity changes are observed. Attempts to model these gravity changes as exponential functions of time were unsuccessful. [less ▲]

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See detailCalibration of a superconducting gravimeter by comparison with an absolute gravimeter FG5 in Boulder
Francis, Olivier UL; Niebauer, T. M.; Sasagawa, G. et al

in Geophysical Research Letters (1998), 25(7), 1075-1078

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See detailProper Usage of the ICET Data Bank - Comparison with theoretical applications on Earth Models
Melchior, Paul; Francis, Olivier UL

in Ducarme, Bernard; Pâquet, Paul (Eds.) Proceedings of the Thirteenth International Symposium on Earth Tides (1998)

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See detailCalibration of the C021 superconducting gravimeter in Membach (Belgium) using 47 days of absolute gravity measurements
Francis, Olivier UL

in Segawa, Jiro; Fujimoto, Hiromi; Okubo, Shubei (Eds.) Gravity, Geoid and Marine Geodesy (1997)

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