Collaborative research on observing the morphological and optical characteristics of the summer Arctic ice cover during the 2005 Trans-Arctic Expedition.

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Funds are provided to acquire a comprehensive dataset of ice cover morphological and optical properties across the Arctic Basin during summer melt and early fall freezeup. This dataset will be a valuable asset for assessing the state of the ice cover, evaluating sea ice models, and interpreting remote sensing data. The specific science objectives of the project include (i) statistically characterizing the morphological and optical properties of the summer ice cover across the Arctic basin, including ice concentration, ice thickness, melt pond coverage, snow depth, ice physical properties, and sediment load, (ii) determining the partitioning of solar radiation between reflection to the atmosphere, absorption within the ice, and transmission to the ocean for summer and early autumn ice conditions, and (iii) archiving and widely disseminating this dataset. The field plan includes on-ice measurements on individual floes and helicopter-based aerial surveys. The on-ice observations will consist of surveys and point measurements of sea ice morphology and optics. The morphology component will include measurements of melt pond area and profiles of ice thickness, topography, and pond and snow depth. The optical observations will consist of spectral albedos, transmittances, and vertical profiles of in-ice irradiance. Helicopter photographic survey flights determining the relative areas of ice, ponds, and leads will extend the surface-based measurements to larger scales. Deployment of 2-3 autonomous ice mass balance buoys, with a three-year life expectancy, will add a temporal component to the project.There is evidence that the partitioning of solar radiation has changed in recent decades. The data from this project will assist in understanding the nature of this change and how it affects the climate dynamics of the Arctic.