| Title | Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica |
| Author | Dempsey, D.E.; Langhorne, P.J.; Robinson, N.J.; Williams, M.J.M.; Haskell, T.G.; Frew, R.D. |
| Author Affil | Dempsey, D.E., University of Otago, Department of Physics, Dunedin, New Zealand. Other: National Institute of Water and Atmospheric Research, New Zealand; Industrial Research, New Zealand |
| Source | Journal of Geophysical Research, 115(C1), Citation C01007. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227 |
| Publication Date | 2010 |
| Notes | In English. 55 refs. GeoRef Acc. No: 300681. CRREL Acc. No: 64005175 |
| Index Terms | cooling; crystals; ice; ice cover; ice crystals; models; porosity; Southern Ocean-- McMurdo Sound; episodic flux; fabric; McMurdo Sound; numerical models; observations; platelet ice; Ross Sea; sea ice; Southern Ocean; three-dimensional models |
| 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. |
| URL | http://hdl.handle.net/10.1029/2008JC005264 |
| Publication Type | journal article |
| Record ID | 88722 |