Processes at the Ice Sheet Boundaries

In RC2, we investigate changes in the Antarctic ice sheet (AIS) mass balance and variability of ice flow across scales through observations of AIS boundaries paired with physical models of the ice sheet and atmosphere to improve our understanding of current and future ice sheet evolution outlining the main objectives below:

Objective (1): Mass and energy exchange in the near-surface polar atmosphere remains poorly understood. Radiation, sublimation, and airborne snow transport will be continuously measured over several years. Vertical profiles of atmospheric boundary layer variables from a tall tower at Princess Elisabeth Station will allow analysing gradients or divergence of radiative and turbulent fluxes and to relate these to specific weather events and their sequencing, including the influence of wind-driven snow transport, extending prior measurements. Synergies with Objective 2 will place these measurements in a broader mechanistic context.

Objective (2): Local isotope measurements will characterise and quantify the processes governing snow deposition in DML. We explore the impact of newly discovered airborne snow metamorphism on optical grain size and isotopic composition, feeding into the ASM project (PI: Walter) and RC1. Airborne and deposited snow microstructures will be measured using the new SnowImager instrument. The snow and vapour isotopic composition and atmospheric parameters will be measured in close collaboration with RC1 and serve as the ground truth for the surface energy and mass balance components in models allowing up-scaling to Antarctic-wide simulations.

Objective (3): The ice-shelf—ice-sheet system determines the rate at which grounded ice enters the ocean. We will acquire new observations of basal boundary conditions (e.g. pinning point geometry, basal melt) beneath grounded ice (Crary Ice Rise (CIR)) and floating ice (grounding zone of Kamb Ice Stream) capturing ice sheet variability from present to the Holocene. These data will inform model projections of sea level in future climates, linking to O5. Autonomous phase-sensitive Radio-Echo Sounders will be used to determine the internal strain and basal mass balance at CIR and Kamb Ice Stream, radar and active source seismology data will refine key inputs for the model, including ice shelf bathymetry, bed roughness, and bed type. O3 is directly related to the sea ice processes and data from the Ross Sea (RC3).

Objective (4): Surface mass balance (SMB) and associated ice flow variability have shaped the behaviour of the ice sheet. Through the analysis of Blue Ice Moraines, our aim is to assess climate and ice sheet dynamics over millennia by quantifying sediment residence times and subglacial transport. Geophysical imaging, multi-nuclide
cosmogenic dating, and radioisotope dating of englacial and basal ice will be used. O4 will link evidence of short-lived extremes with geological records of long-term variability, bridging RC1 and RC2.

Objective (5): Data acquired in RC2 (Objectives 1–4) will provide ground-truth present-day benchmark datasets from regional climate models, gridded products of basal roughness and topography, as well as ice shelf melt rates. The direct link to physical models of the AIS in RC2 will support the translation of the data acquired in the field into larger-scale ice sheet dynamics.

Research Cluster PI

Hendrik Huwald, EPFL, WSL/SLF

Research Cluster Participants

Johannes Sutter, Uni Bern
Naki Akcar, Uni Bern
Huw Horgan, WSL/SLF
Benjamin Walter, WSL/SLF

Links with Participants of other Research Clusters

Franziska Aemisegger, Uni Bern
Alexis Berne, EPFL
Ruzica Dadic, WSL/SLF
Sergi Gonzalez-Herrero, WSL/SLF
Michael Lehning, EPFL, WSL/SLF

Processes at the Ice Sheet Boundaries

Research Cluster PI

Research Cluster Participants

Links with Participants of other Research Clusters

Swiss and International Partners