Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
American Geophysical Union (AGU)
Journal Title
Journal ISSN
Volume Title
Language
en
Date
2010
Authors
Dempsey, David
Langhorne PJ
Robinson NJ
Williams MJM
Haskell TG
Frew RD
Abstract

During the annual growth of landfast ice in McMurdo Sound, Antarctica, an episodic flux of platelet ice crystals from the ocean contributes to the build up of a porous subice platelet layer, which is steadily incorporated into the sea ice cover as it thickens over winter. In November 2007, we examined the spatial variability of these processes by collecting sea ice cores, with simultaneous oceanographic observations, along an east-west transect in the sound. Previously identified draped and bladed platelet ice types were observed. In addition, we identify resumed columnar growth which appears to be a result of geometric selection from the subice platelet layer after the arrival of new platelet crystals from the ocean has ceased. A numerical model of mechanical platelet ice processes is developed that predicts crystal texture and c axis distributions, producing virtual incorporated platelet ice with known growth history. This model demonstrates how a disordered subice platelet layer arises from an initially flat interface and suggests that such a layer is more likely to form later in the growth season. The model also suggests how the grain boundary density in incorporated platelet ice responds to changes in the flux of loose platelet crystals from the ocean. Application of this result to our 2007 platelet ice observations indicates that sea ice in western McMurdo Sound is subject to larger and more persistent platelet fluxes than the ice in the east. This is consistent with the pattern of in situ supercooling just beneath the ocean surface. © 2010 by the American Geophysical Union.

Description
Citation
Dempsey DE, Langhorne PJ, Robinson NJ, Williams MJM, Haskell TG, Frew RD (2010). Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica. Journal of Geophysical Research: Oceans. 115(1).
Keywords
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
0404 Geophysics
0405 Oceanography
0406 Physical Geography and Environmental Geoscience
37 - Earth sciences
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All rights reserved unless otherwise stated