Preliminary results on relationship between thermal diffusivity and porosity of sea ice in the Antarctic

The in situ sea-ice temperature, salinity and density observed from Chinese Antarctic Zhongshan Station have been applied to calculate the vertical profile of sea ice porosity. Based on numerical method, a number of schemes on sea-ice thermal diffusivity versus porosity have been accessed and one optimized scheme is identified by an optimal control model with an advanced distributing parameter system. For simplicity, the internal heating source item was neglected in the heat conduction equation during the identification procedure. In order to illustrate the applicability of this identified scheme, the vertical ice temperature profiles have been simulated and compared with measurements, respectively by using identified scheme and by classical thermodynamic formulae.The comparisons indicated that the scheme describing sea-ice thermal diffusivity and porosity is reasonable. In spite of a minor improvement of accuracy of results against in situ data, the identified scheme has a more physical meaning and could be used potentially in various applications.     

南极海冰导温系数与孔隙率关系初探

利用南极中山站附近固定冰不同季节的温度垂直廓线,冰芯盐度、密度数据,基于Cox等发展的冰内孔隙率计算方法,获得冰内孔隙率的垂直廓线。再通过建立分布参数系统最优控制模型,优化辨识在无热源条件下冰内温度垂直廓线对应的海冰导温系数。通过比较7种冰导温系数同孔隙率的关系,选择出海冰导温系数和孔隙率的最优关系式。用该关系式对同一地点不同年份的海冰进行温度垂直廓线计算,比较辨识的导温系数同孔隙率的关系相对于前人理想海冰模型中的导热系数、比热等公式计算对应条件的海冰垂直温度廓线的优势。两种计算结果说明,辨识得到的关系所引起的偏差在趋势和量级上同理想模式计算的结果相同,但辨识得到的关系更简洁,且更具有物理背景。