Tides of the northwestern Ross Sea and their impact on dense outflows of Antarctic Bottom Water
Tides of the northwestern Ross Sea and their impact on dense outflows of Antarctic Bottom Water
复制标题
DOI：
10.1016/j.dsr2.2008.10.026
复制
发表时间：
2009-06-01
影响因子：
3
通讯作者：
Muench, Robin D.
中科院分区：
文献类型：
--
作者：
Padman, Laurie;Howard, Susan L.;Muench, Robin D.
2003-2005年在罗斯海西北部Drygalski海槽附近的大陆架斜坡区域进行的南极斜坡项目（“AnSlope”）水文和洋流的系泊和深度剖面测量显示，在大陆架断裂附近产生了一种冷的、密集的南极底水（AABW）的高能底栖生物流出。这种外流将大陆架上的浓水生产过程与全球深海的通风结合在一起。我们利用斜坡系泊的底部压力和水流的时间序列，以及一个高分辨率的三维原始方程数值模型，探讨了陆架断裂附近的潮流对流出量输运和水文特性有显著影响的假设。在外陆架和上坡的大潮上，潮流超过1 m s（-1）。在半个潮汐周期中，大潮时的潮汐平流带着大约20公里的水包穿过斜坡，足以将来自Drygalski海槽北部的水平流穿过基底到达大陆架断裂，或者类似地从大陆架断裂（类似于500米水深）到类似于1600米等深线。潮汐校正的拉格朗日平均流阶为0.05-0.1 m s(-1)，流过外陆架和上斜坡。由于水文梯度的平流和能从海底延伸到海洋表面一半以上的高能混合，基岩和上斜坡上的底栖层的厚度和水质量特性表现出明显的潮汐循环。大潮时底栖层的最大参数化潜流扩散率接近1 m(2) s（-1）。潮汐的增加对AABW的时间平均流出量有深远的影响，主要是通过大潮期间底栖层厚度的增加。在一个潮汐周期内平均，坡面上的AABW下坡体积通量在大潮时比小潮时大约大2.5倍，这表明需要在试图表示陆架水对全球海洋环流贡献的大尺度海洋模式中包括潮汐的影响。(C) 2008 Elsevier Ltd版权所有。
Moored and depth-profile measurements of hydrography and currents during the 2003-2005 Antarctic Slope ("AnSlope") program on the shelf-slope region near Drygalski Trough sill in the northwest Ross Sea have revealed an energetic benthic outflow of cold, dense Antarctic Bottom Water (AABW) produced near the shelf break. This outflow couples dense-water production processes on the continental shelf to ventilation of the global deep ocean. We use time series of bottom pressure and currents on the AnSlope moorings, and a high-resolution, three-dimensional, primitive-equation numerical model, to explore the hypothesis that the tidal currents near the shelf break have a significant impact on outflow volume transport and hydrographic properties. Tidal currents exceed 1 m s(-1) at spring tide over the outer shelf and upper slope. Tidal advection at spring tide carries water parcels similar to 20 km across-slope during a half tidal cycle, sufficient to advect water from northern Drygalski Trough across the sill to the shelf break, or similarly from the shelf break (similar to 500 m water depth) down to the similar to 1600 m isobath. A tidally rectified Lagrangian mean flow of order 0.05-0.1 m s(-1) over the outer shelf and upper slope accompanies the spring tide. Thickness and water mass properties of the benthic layer over the sill and upper slope exhibit pronounced tidal cycles due to advection of hydrographic gradients and to energetic mixing that can extend more than halfway up from the seabed to the ocean surface. Maximum parameterized diapycnal diffusivity in the benthic layer at spring tides approaches 1 m(2) s(-1). The addition of tides has a profound effect on time-averaged outflows of AABW, primarily through an increase in benthic layer thickness during spring tide. Downslope volume fluxes of AABW over the slope, averaged over a tidal cycle, are similar to 2.5 times larger at spring tide than at neap, indicating a need to include the effect of tides in large-scale ocean models attempting to represent shelf water contributions to the global ocean circulation. (C) 2008 Elsevier Ltd. All rights reserved.