Numerical study on tidal mixing along the shelf break in the Green Belt in the southeastern Bering Sea
Numerical study on tidal mixing along the shelf break in the Green Belt in the southeastern Bering Sea
复制标题
白令海东南部绿带陆架折断处潮汐混合的数值研究
DOI：
10.1002/2013jc009113
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
and G. S. Carter
中科院分区：
文献类型：
--
作者：
Tanaka;T.;I. Yasuda;Y. Tanaka;and G. S. Carter
潮汐混合及其相关的铁和营养盐通量从一个次表层沿着大陆架休息已被认为是关键过程之一，以维持夏季在白令海东南部的绿色带的高生物生产力。本文利用三维高分辨率数值模式研究了陆架坡折附近的潮汐混合，并根据全日和半日内波的不同特征，对混合的增强进行了定量分析，揭示了其物理机制。在数值模式中，在开放边界上，正压全日潮和/或半日潮强迫下，沿绿色带沿着再现了能量耗散率超过1 × 10− 8 W/kg的强湍流混合。由于半日内波的作用，陆架坡折附近海面的能量耗散增强，而陆架坡折底部附近的能量耗散则由全日地形陷波增强。一个额外的实验与分层的冬季条件下的代表显示了显着的影响，分层的能量耗散的货架打破由于昼夜和半日内波的功能的变化。阿留申海峡的低模态半日斜压能量通量增加了沿着Pribilof和热姆楚格山脉之间陆架坡的能量耗散。这些结果表明，强烈的垂直混合沿着陆架断裂所引起的全日潮和半日潮都发挥了重要作用，在维持铁和营养盐供应沿着绿色带。
Tidal mixing and its associated iron and nutrients flux from a subsurface layer along the shelf break has been considered as one of the key processes to maintain the high summertime biological productivity in the Green Belt in the southeastern Bering Sea. In the present study, tidal mixing near the shelf break is examined with a three‐dimensional high‐resolution numerical model to quantify the enhanced mixing and to reveal the underlying physical mechanisms based on the different characteristics of diurnal and semidiurnal internal waves. Strong turbulent mixing with energy dissipation rates of over 1 × 10−8W/kg is reproduced along the Green Belt in the numerical model forced by barotropic diurnal and/or semidiurnal tides at open boundaries. The energy dissipation off the shelf break near the sea surface is enhanced due to the semidiurnal internal waves, whereas the dissipation near the bottom of the shelf break is enhanced by the diurnal topographically trapped waves. An additional experiment with stratification representative of winter conditions shows a significant influence of stratification on the energy dissipation off the shelf break due to the change in features of both diurnal and semidiurnal internal waves. Low‐mode semidiurnal baroclinic energy flux from the Aleutian Passes is shown to increase the energy dissipation along the shelf slope between Pribilof and Zhemchug Canyons. These results suggest that the strong vertical mixing along the shelf break induced by the diurnal and semidiurnal tides both play important roles in maintaining the iron and nutrients supply along the Green Belt.