| Summary: | This award will support an investigation of the physical properties and state of snow and firn along a traverse from Thule to Summit Greenland. The 'Intellectual Merit' of the study relates to the fact that the Greenland Ice Sheet is an important indicator of the response of the cryosphere to climate and, since the ice sheet contains enough water to raise sea level by 7 meters if it were all to melt, understanding the state of the ice sheet is critically important to scientists, policy-makers and society at large. The scientists will accompany the resupply traverse from Thule to Summit, and make detailed observations of grain size, density and stratigraphy in 1 m deep snow pits and 10 m deep boreholes in firn along a route that crosses all the facies (ablation facies, soaked facies, percolation facies, dry snow facies) of the ice sheet. Techniques to be applied in the field include near infra-red photography, borehole optical stratigraphy and a neutron-scattering probe. A ground-penetrating radar operated along the traverse will provide stratigraphic data that links the stratigraphic information obtained in the snow pits and boreholes. Two shallow ice cores obtained at the beginning and end of the traverse, and snow samples, will be returned to the laboratory for examination of microstructure using micro-computed tomography and brightness temperature using optical and near-infra-red photography. The microstructure results will be used as input to a radiative transfer model and the brightness temperature will be used for validation of the simulations. The study has a variety of 'Broader Impacts'. The traverse lies very close to traverses made in 1952-55 when studies of snow and firn properties established the concept of glaciers facies; a comparison of those results with those of this study will provide valuable insights into changes that have occurred in this region since the mid-1950s. The characterization of the spatial variability of the physical properties of surface and near-surface snow also has application to the interpretation of remote sensing data, which are essential to mapping surface melting across the entire ice sheet. The study will involve a graduate student participant in the Dartmouth College Integrated Graduate Education and Research Traineeship (IGERT) program - 'Polar Environmental Change' - and develop a series of snow-science-themed activities designed for a four week after-school program for grades 3 and 4 at the Montshire Museum of Science. The activities will be run by Dartmouth students trained by museum staff in inquiry-based, hands-on activities. The principal investigators are both early-career scientists.
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