Constraining an Ocean Model Under Getz Ice Shelf, Antarctica, Using A Gravity‐Derived Bathymetry

Romain Millan (1) , Pierre St‐laurent , Eric Rignot , Mathieu Morlighem , Jeremie Mouginot (1) , Bernd Scheuchl

1 IGE - Institut des Géosciences de l’Environnement

Getz Ice Shelf, the largest producer of ice shelf meltwater in Antarctica, buttresses glaciers that hold enough ice to raise sea level by 22 cm. We present a new bathymetry of its sub‐ice shelf cavity using a three‐dimensional inversion of airborne gravity data constrained by multibeam bathymetry at sea and a reconstruction of the bedrock from mass conservation on land. The new bathymetry is deeper than previously estimated with differences exceeding 500 m in a number of regions. When incorporated into an ocean model, it yields a better description of the spatial distribution of ice shelf melt, specifically along glacier grounding lines. While the melt intensity is overestimated because of a positive bias in ocean thermal forcing, the study reveals the main pathways along which warm oceanic water enters the cavity and corroborates the observed rapid retreat of Berry Glacier along a deep channel with a retrograde bed slope.

Domaines: Sciences de l'environnement

Romain Millan, Pierre St‐laurent, Eric Rignot, Mathieu Morlighem, Jeremie Mouginot, et al.. Constraining an Ocean Model Under Getz Ice Shelf, Antarctica, Using A Gravity‐Derived Bathymetry. Geophysical Research Letters, 2020, 47 (13), ⟨10.1029/2019GL086522⟩. ⟨hal-03026251⟩