加拿大海盆双扩散阶梯结构分布与热通量研究

Distribution of Double-diffusive Staircase Structure and Heat Flux in the Canadian Basin

基于2008年中国第三次北极科学考察的CTD数据,研究了北冰洋加拿大海盆的双扩散现象。双扩散对流导致的阶梯状均匀混合在加拿大海盆广泛存在,在加拿大中央海盆及门捷列夫海脊观测到了明显的双扩散阶梯。阶梯结构在深度分布上有显著的空间差异,在100~500 m深度范围内都可能存在双扩散阶梯,稳定的阶梯结构位于温跃层所在深度,阶梯高度1~5 m,深度较大的阶梯通常是复合阶梯。基于双扩散热通量定律,估计由双扩散引起的向上垂直热通量约为0.05~0.22 W/m2,表明大西洋水的热量对加拿大中央海盆上层水的热收支不是重要的。但在楚科奇海台区和加拿大海盆南部海域不存在双扩散阶梯,大西洋水的热量可能对上层海洋结构产生显著影响。

Double-diffusive staircase structure is investigated with CTD profile data in the Canadian Basin obtained from the third Chinese Arctic Expedition in summer of 2008.There exist extensive double-diffusive mixed phenomena in the Canadian Basin.Double-diffusive staircase is observed in the central Canada Basin and Mendeleyev Ridge.The distribution of double-diffusive staircase has significant spatial difference.There exists double-diffusive staircase through the depth range of 100~500 m.The 1 m to 5 m high staircase is located in the depth of thermocline.However,the staircase is not of uniform height in the deeper depth,with a wide depth range,which is called composite staircase.On the basis of double-diffusive flux laws,estimated vertical heat fluxes through the staircase are in the range 0.05~0.22 W/m2,indicating that the vertical transport of heat from the Atlantic Water in the central basin is unlikely to have a significant impact to the Canadian Basin ocean surface heat budget.However,the south on the Canada Basin and Chukchi Plateau where the well-formed staircase is absent possibly dominate the regionally averaged heat flux.