Physical properties, spectral reflectance and thickness development of first year fast ice in Kongsfjorden, Svalbard

A ground truth study was performed on first year fast ice in Kongsfjorden, Svalbard, during spring 1997 and 1998. The survey included sea ice thicknes s monitoring as well as observation of surface albedo, attenuation of optic al radiation in the ice, physical properties and texture of snow and sea ic e. The average total sea ice thickness in May was about 0.9 m, including a 0.2 m thick snow layer on top. Within a few weeks in both years, the snow m elted almost completely, whereas the ice thickness decreased by not more th an 0.05 m. During spring, the lower part of the snow refroze into a solid l ayer. The sea ice became more porous. Temperatures in the sea ice increased and the measurable salinity of the sea ice decreased with time. Due to sno w cover thinning and snow grain growth, maximum surface albedo decreased fr om 0.96 to 0.74, Texture analysis on cores showed columnar ice with large c rystals (max. crystal length >0.1 m) below a 0.11 m thick mixed surface lay er of granular ice with smaller crystals. In both years, we observed sea ic e algae at the bottom part of the ice. This layer has a significant effect on the radiation transmissivity.