Solar Transmission Through Sea Ice in the Fram Strait: Implications for Biology and Climate

ABSTRACT Snow and ice control the light penetration into ice-covered Arctic waters, determining the onset of biological production after the winter. Changes in the snow and ice cover and their characteristics influence both the amount of light and the spectral distribution of light transmitted to the underlying water, with effects on timing, distribution, production rate and even species composition of the Arctic marine production. Light transmitted through the sea ice also provides a source of heat to the upper part of the water column, and may promote melting of the ice from the bottom. Spectral measurements of the transmitted solar flux were made at several locations in the Fram Strait-East Greenland Shelf region in April---May 2008, as part of the iAOOS-Norway project of interdisciplinary observations in the Arctic Ocean, and in September 2007 and 2008. These transmission measurements were made both immediately below ice floes, and as profiles to a depth of 80~m both beneath floes and beneath open water in leads. During the spring cruise, the corresponding biological productivity and biomass in the water column below the ice were measured. Together such data will increase our understanding of how a changing Arctic climate will influence the ecosystem and productivity. This presentation will present results from these transmission measurements, the first of their kind from this important region of sea ice export and biological and oceanographic activity, and their relationship to biological productivity, along with their implications for climate processes, including the formation and melting of sea ice.