Dynamics of coastal outlet glaciers and implications on the overall mass balance of the East Antarctic ice sheet

The Astrolabe glacier serves as a test zone for measuring and understanding the dynamics of East Antarctic outlet glaciers. It is part of the more general observatory CRYOBS-CLIM (https://cryobsclim.osug.fr/) which aims at understanding the links between the environment (essentially climate forcing) and resulting glacier changes. These links operates at two principal levels: (i) climate changes induce surface mass balance changes which indirectly impact the environment and (ii) surface mass balance changes constitute the principal boundary conditions in the dynamic evolution of ice masses.

If the first aspect is principally covered by the GLACIOCLIM Observatory (IPEV program 411), the aim of the present proposal is to tackle these ice dynamics mainly driven by surface mass balance changes and, to a lesser degree, by direct climatic inputs (essentially temperature) and as such, appears fully complementary to the GLACIOCLIM one. Since the ice discharge in Antarctica is by more than 80 % drained by outlet glaciers from the eastern ice sheet, understanding their dynamics and being able to model their present and future behaviour is crucial when addressing the sea level issue.

The proposed approach is double by first proposing a comprehensive survey of the selected test glacier in order to capture the specific dynamics of marine outlet glaciers and feed relevant ice flow models. Corresponding results will then in a second time be applied to the modeling of the large outlet glaciers of the Wilkes-Terre Adelie land sector of east Antarctica whose contribution to sea level is major and needs to be constrained. The core of the activities detailed in the proposed program concerns the first task implying field work on the Astrolabe glacier. As for the second part, it is carried out through an international collaboration of our program with the University of Texas under the form of several aiborne geophysical campaigns. These measurements allow for assessing the environment settings of these large glaciers (bedrock and surface topographies, outlining of respective grounded and floating parts…) necessary for conducting the modeling of their future behaviour.