9400241 Tucker Research supported by this grant is under the auspices of the Arctic Systems Science (ARCSS) Global Change Research Program and is jointly sponsored by the Division of Ocean Sciences and the Office of Polar Programs. The research will be centered around a unique and intensive, multidisciplinary research expedition to parts of the Arctic Ocean that have never been extensively studied. The 1994 U.S./Canada Arctic Ocean Section is a collaborative effort with Canada that will involve approximately 60 scientists on a Canadian and a U.S. icebreaker during summer 1994. NSF-funded projects will focus on hydrography, biology, paleo-, and sea-ice studies. Data collected will be amongst the first ever from several regions of the Arctic Ocean and will be highly relevant to improving our understanding of how the Arctic is an indicator of changing global climate conditions and how it affects the physical, chemical, and biological features of the more temperate oceans and regions. This project is part of the program that focuses on the inter-relationship of sea ice physical and electromagnetic properties. A two stage approach will be undertaken: small-scale detailed studies of the different ice types and large-scale surveys to determine their relative areal coverage. Measurements of spectral albedo, bidirectional reflectance and wavelength integrated albedo at visible and near-infrared wavelengths will be made. Ice cores will be taken and studied for physical state and structure including vertical profiles of temperature, salinity, brine and air volume, crystallography, and inclusion size distribution. These small-scale measurements will be done in conjunction with helicopter surveys of active and passive microwave observations of the same ice to determine the range of physical properties, and to determine the impact of changes in the physical properties on electromagnetic signatures. Helicopter transects, using an airborne spectroradiometer, as well as conventional photographic an d video cameras will be used to determine a quantitative estimate of large-scale albedo, ice concentration, melt pond fraction, and floe size distribution. These large-scale measurements will be linked with small-scale data to provide an understanding of the spatial and temporal variability of ice albedo and the coupling of shortwave irradiance to ice ablation. Such measurements are critical to our understanding of how the Arctic Ocean stores and reflects heat and its influence of climate variability. ***
