(Table 1) Sea ice and snow characteristics and heat fluxes observed during R/V Aurora Australis cruise to East Antarctica in September/October 2007

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 0.15 W/K/m 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/m) 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.

2007年晚冬期间，在海冰物理与生态实验（Sea Ice Physics and Ecosystem Experiment, SIPEX）中，研究人员针对威尔克斯地（Wilkes Land）周边东南极海冰上的积雪属性展开了观测研究，重点关注积雪与海冰的相互作用。本次观测包含11条用于测量冰厚、冰干舷（freeboard）及积雪深度的断面测线；在13块浮冰上布设了50个积雪坑；同时在3块浮冰上开展了地表热通量的日变化观测。沿断面获取的高精度地形剖面数据，以及积雪的δ¹⁸O、盐度和密度数据集，使得该区域首次实现积雪-海冰相互作用的定量分析成为可能。总体而言，与其他东南极区域的观测结果一致，本区域积雪在类型、厚度（均值：0.14±0.13 m）及密度（325±38 kg/m³）上均呈现显著的非均质性。高盐度层局限于积雪底层0.1 m范围内。对该层内盐度与δ¹⁸O数据的分析显示，80%的观测点中，该层的盐水源自海冰表层卤水，剩余20%则源自海水。基于积雪密度的垂直剖面，研究估算得到积雪的整体热导率平均为0.15 W/(K·m)，仅为当前海冰数值模型中所采用值的一半。尽管以此值计算得到的积雪内部向上热通量显著低于海冰内部的热通量，但研究表明，采用0.3~0.4 W/(K·m)的热导率取值，更适于当前数值模型中冰生长量的估算。日变化观测结果表明，积雪内部的向上传导热通量与地表净长波辐射，在雪泥形成海冰的过程中发挥了重要作用。高精度的地表地形数据使得研究人员能够对比中性条件下冰面与雪面的空气-冰拖曳系数，并探讨通过卫星遥感反演冰厚分布的可行性。研究发现，整体而言积雪覆盖并非削弱而是增强了海冰的地表粗糙度，使拖曳系数提升约10%。在冰厚反演方面，平均冰厚与冰面粗糙度的相关性高于平均冰干舷或地表高程，这表明卫星L波段合成孔径雷达（L-band SAR）在季节性海冰区域的冰厚分布估算中具有潜在应用价值。