Impacts of Increased Light Transmittance on Ocean Heating, Primary Productivity, and Carbon Cycling Across a Pacific Arctic Continental Shelf Gradient

Seasonal sea ice in the Pacific Arctic region has declined significantly, with large portions of this region becoming ice-free by mid-summer. This Pacific Arctic sector is also among the most biologically productive marine ecosystems in the world and acts as an important sink and perhaps seasonal source of carbon. Although sea ice is a dominant feature in these shelf environments at high-latitudes, we are only beginning to understand how changes in sea ice cover (through its influence on light, seawater temperature, salinity, and nutrient availability) will specifically affect ecosystems in these regions. This NSF RAPID project adds new optical measurements of light transmittance through the upper ocean water column across a continental shelf gradient to an existing suite of observations on the Synoptic Arctic Survey cruise to the central Arctic Ocean in the fall of 2022. The research will test the hypothesis that light transmittance increases with declines in sea ice cover and varies with light absorbing impurities in the water column, and utilize the optical measurements to elucidate questions surrounding vertical heat distribution in the water column, primary productivity, and the photodegradation of dissolved organic matter.