Ground-based gravimetry for measuring small spatial-scale mass changes on glaciers
Cecilie, Rolstad DenbyProject period: 2007-2009.
Staff: C. Rolstad, and PhD student K. Breili.
Gravitasjonsmålinger, Hardangerjøkulen
Photo: K. Breili
Gravity change on a glacier surface is a composite of several effects (e.g. melting andaccumulation of snow and ice, redistribution of mass with depth by refreezing of meltwater and heightand thickness changes of the snow and ice layers). Models and equations necessary to estimate the measured gravity change due to different effects are discussed, and the propagation of observational errors is evaluated. We have gained experiences with ground-based gravity measurements carried out on Hardangerjøkulen, Norway, in spring and autumn 2007. It was found that the vertical gradient of gravity contributes most to the uncertainty in the determined mass change. With present instrumentation, gravity can be measured with the required accuracy to determine the mass loss to 10% of the loss determined by conventional mass-balance measurements. Improvements in field procedures to achieve the required accuracy for measuring the mass/density changes directly, combining gravity measurements and GNSS (Global Navigation Satellite Systems), are discussed.
This work is conducted in cooperation with the Norwegian Water Resources and Energy Directorate (NVE).
Publication
Breili, K. And C. Rolstad, 2009. Ground based gravimetry and GPS for measuring small scale mass changes on glaciers. Annals of Glaciology 50(50), 141-147.
Published: 16.04.00
Updated: 16.04.10
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Contact: Cecilie Rolstad (cecilie.rolstad@umb.no)