Collaborative Research on Sunlight and the Arctic Atmosphere-Ice-Ocean System

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AbstractThe distinct annual cycle of solar radiation is a defining feature of the Arctic system. The lack of sunlight in winter and the long daylight hours in summer control the seasonal cycle of the surface heat budget, structure both terrestrial and marine ecosystems, drive the seasonal build-up and sequestration of carbon and play a major role in the cycling of major atmospheric constituents. One of the most important aspects of the disposition of solar radiation within the Arctic system is the reflection, absorption and transmission of sunlight by the atmosphere-sea ice-ocean system (AIOS). The overall goals of this study are to enhance our understanding of the present role that solar radiation plays in the Arctic AIOS and to improve our ability to predict the future role. This will be accomplished through an integrative and synthetic approach. Data will be collected from a wide range of sources including laboratory studies, field experiments, and satellite observations. An error analysis and data gap assessment will be a central component of the synthesis activity. Process models, ice-ocean models, and reanalysis products will be used to fill the gaps in the dataset. The primary product of this synthesis effort will be a 20-year, pan-Arctic description of the interaction of solar radiation with the AIOS. In particular, we will determine spectral values from 250 to 2500 nm of the incident solar energy, the reflected solar energy, and the solar energy absorbed in the snow, sea ice, and upper ocean. Values will be computed on a monthly, pan-Arctic basis from 1987 to 2007 using the 25 x 25 km Equal Area Scalable Earth Grid. The influx of (solar) heat into the Western Arctic through Bering Strait will also be examined in detail, since the largest changes in ice extent and ice thickness have been observed in this sector of the Arctic. This proposed synthesis of solar radiation in the Arctic AIOS will contribute several key elements to the larger synthesis of the Arctic System including: an assessment of the recent changes in solar energy input to the Arctic Ocean in relation to the observed changes in ice cover and ice mass balance; an evaluation of polar amplification through the ice-albedo feedback; information on the distribution of solar energy available for driving the biological production in the under-ice and upper ocean environments; and insights into the potential changes in and impacts of solar energy distribution as predicted by climate change models.