Avannarleq and Kujalleq Glacial Stability

The evolution of Greenland glaciers in a warming climate depends on their
depth below sea level, flow speed, surface melt, and ocean-induced
undercutting at the calving front. We present an innovative mapping of bed
topography in the frontal regions of Sermeq Avannarleq and Kujalleq, two
major glaciers flowing into the ice-choked Torssukatak Fjord, central west
Greenland. The mapping combines a mass conservation algorithm inland,
multi-beam echo sounding data in the fjord, and high-resolution airborne
gravity data at the ice-ocean transition where other approaches fail. We
obtain a reliable, precision (± 40 m) solution for bed topography across
the ice-ocean boundary. The results reveal a 700-m deep fjord that
abruptly ends on a 100-300 m deep sill along the calving fronts. The
shallow sills explain the presence of stranded icebergs, the resilience of
the glaciers to ocean-induced undercutting, and their remarkable stability
over the past century. An. L., E. Rignot, J. Mouginot, R. Milan, (2018), A
century of stability of Avannarleq and Kujalleq glaciers, West Greenland,
explained using high-resolution airborne gravity and other
data, Geophys. Res. Lett., 10.1002/2018GL077204.