Rapid cross-density ocean mixing at mid-depths in the Drake Passage measured by tracer release
Rapid cross-density ocean mixing at mid-depths in the Drake Passage measured by tracer release
复制标题
通过示踪剂释放测量德雷克海峡中部深度的快速交叉密度海洋混合
作者：
Watson A
在全球海洋翻转环流中，跨密度面的贯叶混合是一个重要的过程。然而，大部分海洋内部的混合被认为只有密度较低的沃茨向下混合关闭全球环流所需的十分之一。这种不足部分是由在与粗糙海底地形有关的有限“热点”中发生的强烈近海底混合所弥补的，但尚不清楚1 000至3 000米中间深度的沃茨是通过交叉密度混合还是通过沿密度流动返回海面。在这里，我们表明，中层深度（1,500米）的沃茨的diapycnal混合经历了持续的20倍的增加，南极绕极电流流经德雷克通道，南美洲和南极洲之间的南端。我们的研究结果是基于一个开放的海洋示踪剂释放三氟甲基五氟化硫。我们归因于增加的混合产生的湍流的深远的南极绕极流，因为它流过粗糙的底部地形在德雷克海峡。我们观察到的混合与全球翻转的南部分量是一致的，其中约有20个sverdrups（1 Sv = 106 m3 s −1）在南大洋上升，交叉密度混合占总数的很大一部分（20%至30%），其余的沿着沿着恒定密度表面上升。绝大多数的底通量是与粗糙海底地形的限制区域相互作用的结果。
Diapycnal mixing (across density surfaces) is an important process in the global ocean overturning circulation,,. Mixing in the interior of most of the ocean, however, is thought to have a magnitude just one-tenth of that required to close the global circulation by the downward mixing of less dense waters. Some of this deficit is made up by intense near-bottom mixing occurring in restricted ‘hot-spots’ associated with rough ocean-floor topography,, but it is not clear whether the waters at mid-depth, 1,000 to 3,000 metres, are returned to the surface by cross-density mixing or by along-density flows. Here we show that diapycnal mixing of mid-depth (∼1,500 metres) waters undergoes a sustained 20-fold increase as the Antarctic Circumpolar Current flows through the Drake Passage, between the southern tip of South America and Antarctica. Our results are based on an open-ocean tracer release of trifluoromethyl sulphur pentafluoride. We ascribe the increased mixing to turbulence generated by the deep-reaching Antarctic Circumpolar Current as it flows over rough bottom topography in the Drake Passage. Scaled to the entire circumpolar current, the mixing we observe is compatible with there being a southern component to the global overturning in which about 20 sverdrups (1 Sv = 106m3s−1) upwell in the Southern Ocean, with cross-density mixing contributing a significant fraction (20 to 30 per cent) of this total, and the remainder upwelling along constant-density surfaces. The great majority of the diapycnal flux is the result of interaction with restricted regions of rough ocean-floor topography.
登录
查看更多内容
海洋学：海洋中的垂直混合
影响因子：
64.8
作者：
David J. Webb;N. Suginohara
通讯作者：
N. Suginohara
海水中六氟化硫的分析
影响因子：
--
作者：
R. Wanninkhof;J. Ledwell;A. Watson
通讯作者：
A. Watson
影响因子：
3.5
作者：
J. Zika;B. Sloyan;T. McDougall
通讯作者：
T. McDougall
影响因子：
3.2
作者：
McClean, Julie L.;Bader, David C.;Worley, Patrick H.
通讯作者：
Worley, Patrick H.
使用 SF5CF3 进行海洋示踪剂释放实验
影响因子：
5.2
作者：
D. T. Ho;J. Ledwell;W. Smethie
通讯作者：
W. Smethie