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Properties of snow overlying the sea ice off East Antarctica in late winter, 2007

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Title: Properties of snow overlying the sea ice off East Antarctica in late winter, 2007
Authors: Toyota, Takenobu Browse this author →KAKEN DB
Massom, Robert Browse this author
Tateyama, Kazutaka Browse this author
Tamura, Takeshi Browse this author →KAKEN DB
Fraser, Alexander Browse this author
Keywords: Antarctic snow on sea ice
Thermal conductivity of snow
Snow ice formation
Air-ice drag coefficient
Retrieval of ice thickness from satellite
Issue Date: May-2011
Publisher: Elsevier
Journal Title: Deep Sea Research Part II : Topical Studies in Oceanography
Volume: 58
Issue: 9-10
Start Page: 1137
End Page: 1148
Publisher DOI: 10.1016/j.dsr2.2010.12.002
Abstract: The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal variation of surface heat flux on three ice floes. The detailed profiling of topography along the transects and the d18O, salinity, and density datasets of snow made it possible to examine the snow-sea-ice interaction quantitatively for the first time in this area. In general, the snow displayed significant heterogeneity in types, thickness (mean: 0.14 ± 0.13 m), and density (325 ± 38 kg m^[-3]), as reported in other East Antarctic regions. High salinity was confined to the lowest 0.1 m. Salinity and d18O data within this layer revealed that saline water originated from the surface brine of sea ice in 20% of the total sites and from seawater in 80%. From the vertical profiles of snow density, bulk thermal conductivity of snow was estimated as 0.15W K^[-1] m^[-1] on average, only half of the value used for numerical sea ice models. Although the upward heat flux within snow estimated with this value was significantly lower than that within ice, it turned out that a higher value of thermal conductivity (0.3 to 0.4 W K^[-1] m^[-1]) is preferable for estimating ice growth amount in current numerical models. Diurnal measurements showed that upward conductive heat flux within the snow and net long-wave radiation at the surface seem to play important roles in the formation of snow ice from slush. The detailed surface topography allowed us to compare the air-ice drag coefficients of ice and snow surfaces under neutral conditions, and to examine the possibility of the retrieval of ice thickness distribution from satellite remote sensing. It was found that overall snow cover works to enhance the surface roughness of sea ice rather than moderate it, and increases the drag coefficient by about 10%. As for thickness retrieval, mean ice thickness had a higher correlation with ice surface roughness than mean freeboard or surface elevation, which indicates the potential usefulness of satellite L-band SAR in estimating the ice thickness distribution in the seasonal sea ice zone.
Type: article (author version)
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 豊田 威信

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