On the Role of Basal Friction and Ice Rheoloy in Constraining the Evolution of Upernavik: Insights from DataAssimilation of Velocity Time Series into the Ice Sheet System Model.

Abstract:

Newly released and processed time series of surface velocities for the Upernavik Glacier, Greenland, are
assimilated into the Ice Sheet System Model to reconstruct the evolution of the glacier since 2008, its underlying basal friction at the ice/bed interface, and the ice rheology throughout the glacier, especially at the shear margins, where softening from cryo-hydrological warming and lateral shearing play a critical role. Several key questions are investigated: 1) the interaction between calving at the ice front, loss of lateral butressing at the shear margins, and the evolution of basal friction; 2) the role of basal topography in controlling all five of Upernavik Glacier tributaries, and the sensitivity of basal stress to reconstructions of the latter and 3) the importance of cryo-hydrological warming, and how it compares with other factors such as calving and butressing in understanding ice-flow dynamics. The time scales we will investigate range from weeks to years, and will heavily rely on the newly developed data assimilation capabilities of the Ice Sheet System Model.

This work was performed at the California Institute of Technology's Jet Propulsion Laboratory under
a contract with the National Aeronautics and Space Administration's Cryosphere Science Program.