Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux

Type de document

ARTICLE A COMITE DE LECTURE REPERTORIE DANS BDI (ACL)

Langue

anglais

Auteur

LE MEUR ; SACCHETTINI ; GARAMBOIS ; BERTHIER ; DROUET ; DURAND ; YOUNG ; GREENBAUM ; BLANKENSHIP ; HOLT ; RIGNOT ; RIGNOT ; MOUGINOT ; GIM ; KIRCHNER ; DE FLEURIAN ; GAGLIARDINI ; GILLET-CHAULET

Résumé / Abstract

The grounding line is a key element acting on the dynamics of coastal outlet glaciers. Knowing its position accurately is fundamental for both modelling the glacier dynamics and establishing a benchmark to which one can later refer in case of change. Here we map the grounding line of the Astrolabe Glacier in East Antarctica (66°41' S; 140°05' E), using hydrostatic and tidal methods. The first method is based on new surface and ice thickness data from which the line of buoyant flotation is found. We compare this hydrostatic map with kinematic GPS measurements of the tidal response of the ice surface. By detecting the transitions where the ice starts to move vertically in response to the tidal forcing we find control points for the grounding line position along GPS profiles. %If it can be shown that the long-term viscous mechanical behaviour of the ice slab validates the hydrostatic approach, mapping the grounding line from the ice supper surface displacements conversely requires correcting for the rigid elastic slab effect that dominates at tidal frequencies. With the help of a 2-dimensional elastic plate model, rigid elastic deviations are computed and applied to these control points. Once the extent of the grounding zone, the kinematic approach is consistent with the hydrostatic map. These two approaches lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates from those obtained so far from satellite imagery.

Source

Cryosphere, num. 4, pp. 3969-4014 p.

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