Author(s): A. J. Gough; A. Mahoney; P. J. Langhorne; N. Robinson; M. J. M. Williams; C. L. Stevens; T. G. Haskell
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Keywords: No Keywords
Abstract: As the sea ice growth season progresses in McMurdo Sound, Antarctica, interaction of the ocean with the nearby McMurdo and Ross ice shelves introduces supercooled water to the Sound. This development at the ice/water interface disrupts the strongly aligned crystal fabrics, typical of columnar growth in the presence of prevailing ocean currents, to produce weakly aligned platelet ice. We established two ice study sites in McMurdo Sound over the winter of 2009. At each site temperature strings with a 30mm sensor spacing were installed from May to October. Ocean temperature, salinity and currents were recorded using ice tethered moorings and CTD casts to the ocean floor. Nearsurface currents were measured by acoustic current meters mounted through the ice in heated huts. The condition of the ice/water interface was monitored from these huts using a camera mounted on an L-arm. A series of 90 mm diameter ice cores were taken from both sites at the end of the winter and the ice structure and crystal orientations were analyzed. We present our crystallographic measurements showing a sharp disruption of columnar growth from an aligned to a disordered fabric and the subsequent relaxation to a partially aligned girdle fabric. We link these measurements to ice growth rates calculated from in-situ temperature records and to oceanographic conditions present at the time of growth.
Year: 2010