Ekman Veering, Internal Waves, and Turbulence Observed under Arctic Sea Ice
Ekman Veering, Internal Waves, and Turbulence Observed under Arctic Sea Ice
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DOI：
10.1175/jpo-d-12-0191.1
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发表时间：
2014-05-01
影响因子：
3.5
通讯作者：
Thwaites, Fredrik T.
中科院分区：
文献类型：
--
作者：
Cole, Sylvia T.;Timmermans, Mary-Louise;Thwaites, Fredrik T.
使用配备速度传感器 (ITP-V) 的第一台冰系系剖面仪 (ITP) 的 2009-10 冬季观测数据，在惯性到月时间尺度上对冰海系统进行了研究。 7米深度的表面风、冰速和海洋速度的波动是相关的。观测到的海洋速度主要指向冰速度的右侧，并顺时针旋转，同时随着穿过混合层的深度而衰减。在整个记录过程中观察到了冰和底层海洋的惯性和潮汐运动。就在冰海界面下方，获得了湍流垂直热、盐和动量通量以及湍流耗散率的直接估计。内波活动升高的时期与湍流热和盐通量的变化以及主要在混合层内的分层有关。湍流热和盐通量相关，特别是当混合层最接近冰冻温度时。使用恒定的冰海阻力系数、基于行星和几何尺度的混合长度或罗斯贝相似理论，动量通量与速度剪切充分相关。艾克曼粘度描述了混合层上的速度剪切。冰海剪切力某些方向的冰海阻力系数升高，这意味着冰地貌以线性脊为特征。混合长度最好使用惯性子范围开始的波数或可变阻力系数来估计。对此数据集和未来 ITP-V 数据集的分析将促进对冰海相互作用及其在数值模型中的参数化的理解。
The ice-ocean system is investigated on inertial to monthly time scales using winter 2009-10 observations from the first ice-tethered profiler (ITP) equipped with a velocity sensor (ITP-V). Fluctuations in surface winds, ice velocity, and ocean velocity at 7-m depth were correlated. Observed ocean velocity was primarily directed to the right of the ice velocity and spiraled clockwise while decaying with depth through the mixed layer. Inertial and tidal motions of the ice and in the underlying ocean were observed throughout the record. Just below the ice-ocean interface, direct estimates of the turbulent vertical heat, salt, and momentum fluxes and the turbulent dissipation rate were obtained. Periods of elevated internal wave activity were associated with changes to the turbulent heat and salt fluxes as well as stratification primarily within the mixed layer. Turbulent heat and salt fluxes were correlated particularly when the mixed layer was closest to the freezing temperature. Momentum flux is adequately related to velocity shear using a constant ice-ocean drag coefficient, mixing length based on the planetary and geometric scales, or Rossby similarity theory. Ekman viscosity described velocity shear over the mixed layer. The ice-ocean drag coefficient was elevated for certain directions of the ice-ocean shear, implying an ice topography that was characterized by linear ridges. Mixing length was best estimated using the wavenumber of the beginning of the inertial subrange or a variable drag coefficient. Analyses of this and future ITP-V datasets will advance understanding of ice-ocean interactions and their parameterizations in numerical models.