The influence of icebergs on landfast sea-ice around Greenland

Landfast sea-ice is sea-ice that remains immobile for a period of time near the coast despite dynamic forcing from the ocean and atmosphere. The dynamics of landfast sea-ice is not fully understood but in shallow shelf seas, there are evidence that ice keels act as anchor points.

Local hunters in Greenland utilize the landfast sea-ice for dog sledge travels, hunting and fishing, thus Greenlandic communities can benefit from skillful predictions of the sea-ice cover. Such sea-ice forecasts are especially valuable if they can predict the date when landfast sea-ice will form or break-up. Therefore it is important that the sea-ice model includes a good description of the processes that govern landfast ice.

In recent years new landfast ice parametrizations have been developed, that includes the additional friction caused by ridge keels touching the sea floor. Additionally, an increased tensile strength of sea-ice is known to help keep the ice stationary also in deeper regions of the sea. Despite the inclusion of these parametrizations the landfast sea-ice evolution is not well represented in Greenlandic waters. One theory is that grounded icebergs act as anchor points. Grounded immobile icebergs can act as artificial islands around which "land"fast sea-ice can form.

This study is split in two. The first part will utilize a newly developed iceberg climatology based on detections of icebergs using Sentinel-1 SAR (Synthetic Aperture Radar) images to study the correlation between observations of icebergs and landfast sea-ice based on ice charts.

The second part of the study will investigate whether it is possible to include this knowledge in a high-resolution coupled ocean (HYCOM) and sea-ice (CICE) model to simulate landfast sea-ice conditions around Greenland. We will investigate how well the recently implemented landfast sea-ice parametrizations perform in the fjords of Greenland and discuss possible concepts for new iceberg based landfast sea-ice parametrizations.