2015.03.25 | Egon Randa Frandsen

Date Sat 08 Aug Sat 29 Aug
Time 00:00    00:00
Location Station Nord

The objective is to describe the distribution and characteristics of the sediments found in the glacier ice, water column and sea ice, and to determine the physical mechanisms involved. Sediment dynamics has not been studied in the region, however in general, sediment sources will include the melting glacier ice and coastal erosion, and ocean currents and turbulence provide the forcing to keep sediments in suspension. As sea ice forms in fall, frazil ice scavenges sediment and entrains it into the ice cover, a process called suspension freezing. This results in sediment-rich granular ice layers in the ice cover. Satellite images confirm that surface melting during summer then tend to concentrate sediment in layers at the surface, significantly affecting sea ice surface albedo and melt rates. However, concentrated patches of sediment may also preferentially melt ice around them forming so-called cryoconite holes that may eventually melt through the ice cover and affect the permeability. This area has unique perennial landfast ice, which has undergone numerous growth-melt cycles, with a texture and sediment distribution that may reflect a history of physical processes. In conjunction with oceanographic and ice thermodynamic sampling, this project relies on optical methods to determine the concentration, size distribution and absorption of the particle assemblages found in the three media: seawater, sea ice, and glacier ice. Methods include using a Satlantic free-falling profiler (with spectral irradiance, CTD, backscattering, chl-a, and CDOM), a Sequoia LISST-100X (particle sizes in seawater and ice), and laboratory analysis of ice cores and water samples.

 

Field site: Villum Research Station, Station Nord, Greenland

PI: Jens Ehn (CEOS)

Participants: TBA

Environment, climate and energy, Arctic Research Centre