Ocean-ice Interaction of peripheral Greenland Glaciers
Peripheral glaciers on Greenland, i.e. ice masses that are not dynamically coupled to the ice sheet since they are either entirely detached, or separated from the ice sheet by well-defined ice divides, account for approximately 5 % of the ice area on Greenland. They account for even only approximately 1 % of the ice volume.
However, because their surface is generally situated at far lower elevations than that of the ice sheet, they are more sensitive to moderate temperature change. Subsequently, their surface mass balance accounts for approximately 25 % of the total mass balance of Greenland: during the period 2000 to 2011, the ice sheet was estimated to have contributed 0.6 mm sea-level equivalent (SLE) per year, during the same time the peripheral glaciers were estimated to have contributed 0.2 mm SLE per year. While on long time scales the contribution of the peripheral glaciers to sea level rise is necessarily limited by their comparatively small volume, they are essential for accounting for Greenland’s contribution to sea level rise during the 20th and 21st centuries.
More than one third of the area of peripheral glaciers is contained in tide water glaciers. There are no comprehensive estimates on the rates of frontal ablation (i.e., calving, subaerial and subaqueous frontal melting), but it is safe to assume that these processes add a substantial portion to the surface melt of peripheral glaciers, and thus are substantial also for the total mass change of Greenland. The unsolved problem of quantifying ocean-ice interaction is also of strong relevance on the global scale, since globally, about 40 % of the area of glaciers (i.e. outside of the ice sheets in Antarctica and Greenland) is contained in tidewater glaciers, and glaciers were globally estimated to contribute 0.9 mm SLE per year during 2000 to 2011.
In the framework of this project, we will develop, implement, validate, and apply parameterizations for frontal ablation of peripheral Greenland glaciers in the Open Global Glacier Model (OGGM). OGGM is developed in an international collaboration under the lead of Ben Marzeion and able to model the surface mass balance of each of the world’s 200 000 glaciers individually. It is the only global glacier model explicitly calculating ice flow, which is a prerequisite for explicitly accounting for the frontal ablation processes resulting from ocean-ice interactions.
The development and implementation of the parameterizations for frontal ablation will be performed in collaboration with the groups working on ocean-ice interaction of the ice sheet outlet glaciers, with a special emphasis on the scale differences between peripheral and outlet glaciers, and based on the data obtained from the oceanographic and glaciological field work program of the joint project. Data from the remote sensing component of the joint project will be essential for optimization and (cross) validation. Total freshwater production rates from peripheral glaciers will be provided with their pour points to the ocean modeling groups.