Ekman漂流是上层海洋普遍存在的一种运动形式。本文提出了用实测温盐数据计算冰下Ekman流速的计算方法,与2010年北极考察期间同步获取的海流剖面数据进行比较,获得了满意的结果。基于这个结果,可以通过比较容易获得的温盐数据,计算Ekman漂流垂直结构。海水层化的存在导致在跃层处湍流黏性系数减小,强烈抑制了流速的向下传播,致使Ekman漂流在跃层处完全消失。结果表明,冬季上层海洋漂流会发生在较大的深度上,而夏季海冰拖曳引起的漂流只能达到20～30m的深度。Ekman漂流的深度只与跃层的深度有关,与海冰的漂移速度无关。漂流层变浅意味着海冰拖曳做功产生的能量不能进入海洋深处,而是在很浅的表层水体内积聚,有利于加剧海冰的底部融化。计算湍流黏性系数通常需要密度剖面和流速剖面的观测结果,在只有密度剖面的情况下,可以采用本文的方法计算Ekman漂流,获得上层海洋的湍流黏性系数剖面。

Ekman drift is a prevalent movement in upper oceans driven by wind stress,and also appears in ice covered oceans driven by ice stress.A method is proposed in this paper to calculate the Ekman Drift under sea ice by in situ temperature and salinity data.Based on this method,the Ekman Drift under sea ice could be estimated by temperature and salinity data by using the PP algorithm proposed by Pacanowski and Philander(1981).With the density profile,Ekman Drift and turbulent viscosity could be obtained simultaneously by iteration.The method is validated to be consistent with current profile data obtained in the Arctic cruise of 2010.The turbulent viscosity will deduce near the pycnocline in the stratified water,where the momentum will be prohibited to transport downward and the Ekman Drift disappeared totally under the pycnocline.Therefore the Ekman Drift in summertime can only reach to 20~30 m depth,whereas in wintertime it can appear much deeper.The depth of Ekman Drift is only related with the depth of pycnocline and independent of the ice drifting speed.The shallower depth of Ekman Drift results in energy accumulation in upper oceans,which benefits bottom melting of sea ice.