| David Dempsey |
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University of Otago, MSc Platelet Ice in McMurdo Sound, Antarctica Platelet ice is a type of sea ice that appears close to ice shelves and when there is supercooling in the water column. It may occur as a loose crystal matrix beneath the sea ice cover that accumulates from the buoyant rising of many individual crystals, or it may be frozen into the sea ice itself. Structurally, platelet ice crystals are broad, thin and leaf-like in appearance, and may be up to tens of centimetres in width. Their accretion and inclusion into the sea ice sheet alters the growth rate, thickness and structure of McMurdo Sound sea ice. This research aims to further the understanding of sea ice growth in the presence of platelet ice through the use field observations and a 3-dimensional numerical model. McMurdo Sound, Antarctica is an ideal 'natural laboratory' for such a study, providing regions of varying spatial and temporal platelet abundance. While platelet ice has only been observed in a small number of locations, its correlation to ice shelves and recent modelling suggest that it may make a considerable contribution to total Antarctic sea ice thickness (Hellmer, 2004). A 2-dimensional model of sea ice growth without loose platelets is currently under construction (following Kawano and Ohashi, 2006) and will be extended to 3-dimensions to simulate growth in the presence of accreting platelets. Particular interest will be paid to the effect of loose platelet abundance and the extent of its in situ growth on the resulting sea ice structure. Observations of McMurdo Sound sea ice collected in 2007 will be compared with simulation results to draw links between platelet abundance and sea ice structural characteristics. Publications |