【摘要】 雪热传导系数是海冰质量平衡过程中的重要物理参数,决定了穿透海冰的热传导通量。北冰洋海冰质量平衡浮标观测获得多年冰上冬季温度链剖面可以明显地区分冰雪界面。本文考虑到冰雪界面处温度随时间变化,再根据冰雪界面热传导通量连续假定,提出了新的雪热传导系数计算方法。受不同环境因素影响,多年冰上各个浮标的雪热传导系数在0.23～0.41 W/(m·K)之间,均值为(0.32±0.08) W/(m·K)。北冰洋多年冰上冬季穿过海冰的热传导通量最大发生在11月至翌年3月,约14～16 W/m~2。结冰季节,来自海冰自身降温的热量对穿过海冰向大气传输的热量贡献逐月减少,从9月100%减小到12月的35%,翌年的1月至3月稳定在10%左右。夏季,短波辐射通能量通过热传导自上而下加热海冰,海冰上层温度高于下层,热量传播方向与冬季反向,往海冰内部传递。直到9月短波辐射完全消失,气温下降,热量再次转变为自下往上传递。从冰底热传导来看,夏季出现海冰向冰水界面传递热量现象。由于雪较好的绝热性,冰上覆雪极大地削弱了海冰上层热传导通量,从而减缓了秋冬季节的结冰速度。尽管受雪厚影响,多年冰上层热传导通量与气温依旧具有很好的线性关系,气温每降低1℃,热传导通量增加约0.59 W/m~2。更多还原

【Abstract】 Thermal conductivity of snow(k_s) is an important physical parameter for sea ice thermodynamics, which controls the conductive heat flux through the ice. The winter temperature profiles from ice mass balance buoys(IMB) on Arctic perennial sea ice can clearly distinguish the snow-ice interface. Considering the temporal variation of the temperature near the snow-ice interface, a new method for determining the k_s was proposed by exploiting the continuity of the heat flux at the snow-ice interface. Influenced by different circumstance, the k_s on different IMB ranged from 0.23 W/(m·K) to 0.41 W/(m·K), with a mean value of(0.32±0.08) W/(m·K). Maximum conductive heat flux through perennial sea ice occurred from November to March, about 14 W/m~2 to 16 W/m~2. In freezing season, the contribution of the specific heat flux from ice cooling in the upward heat lose through ice to atmosphere decreased gradually, from 100% in September to 35% in December, and maintained around 10% from January to March. In summer time, as the heating from ice surface to bottom, temperature of the sea ice upper layer was higher than the lower layer, and the conductive heat transferred downward. Until the solar radiation disappeared in September, air temperature decreased, the conductive heat transferred upward again. As the ice bottom conductive heat flux revealed, a portion of heat transferred from ice to ice-ocean interface in summer time. The low thermal conductivity of snow made it an effective insulator thereby impacting the growth and decay of the underlying sea ice, as well as reducing the transfer of heat between the ocean and atmosphere. The snow covered sea ice upper layer conductive heat flux still showed good relationship with air temperature. For every 1℃ decrease in air temperature, the conductive heat flux increased 0.59 W/m~2.更多还原