Subproject 5: Ice-ocean interaction at Greenland's peripheral glaciers
Peripheral glaciers (PG) represent only a small part of the surface and ice volume of Greenland, but disproportionately affect the mass change of the Greenland Ice Sheet. They also contribute a particularly sensitive part of Greenland's freshwater balance. While there are relatively robust estimates of the surface mass balance of the PG (often referred to as the "climatic" mass balance, since these are interactions between ice and the atmosphere), there is no estimation for the role of the ocean-ice interaction for the mass change of Greenlandic PG. We do not only lack a quantitative estimation of the PG's contribution to the overall mass balance, but also a qualitative understanding of the relevance of the processes contributing to the mass change. Since the spatial distribution of the PG is significantly different from the distribution of the outlet glaciers of the Greenland ice sheet, it can be assumed that the freshwater originating from PG is responsible for other interactions between ocean and ice compared to the meltwater of the ice sheet. In any case, especially in modeling, due to the differences in scale between PG and the ice sheet, a separate treatment is required to account for the share of PG in Greenland's water balance. Subproject 5 "Peripheral Glaciers" intends to improve our understanding of the processes that influence the behavior of the PG. For the first time, a parameterization of the ice-ocean interactions developed specifically for Greenlandic PGs will be implemented, calibrated, validated and applied in an existing glacier model. The glacier model used is able to reconstruct and project the dynamics, geometry and mass balance of each and every PG of Greenland by means of several coupled flowlines. From this - in combination with corresponding data for the ice sheet from other sub-projects of the network - a model-based, complete (ie also considering the calving of the PG) estimate of the mass change of Greenland will be available for the first time.