On the Consumption of Antarctic Bottom Water in the Abyssal Ocean
On the Consumption of Antarctic Bottom Water in the Abyssal Ocean
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DOI：
10.1175/jpo-d-14-0201.1
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发表时间：
2016-02-01
影响因子：
3.5
通讯作者：
Garabato, Alberto C. Naveira
中科院分区：
文献类型：
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作者：
de Lavergne, Casimir;Madec, Gurvan;Garabato, Alberto C. Naveira
深海主要由南极洲周围形成的寒冷、稠密的海水填充，统称为南极底水（AABW）。在稳定状态下，海洋内部必须以产生AABW的速度消耗AABW，但是如何以及在哪里实现这种消耗仍然知之甚少。本文给出了地热加热和参数化内波驱动混合作用下深海水体质量转化的估计。本研究利用潮汐和地转运动与地形相互作用的能量输入图，结合能量耗散分布的假设，来评估由破碎的内潮和背风波引起的无中性输运。地热转化是根据地热通量图来评估的。在构建浮力通量气候学的假设基础上，作者计算出局部消散的内部潮汐和地热加热分别贡献了大约8和5 Sverdrups (Sv；1 Sv相当于10(6)m（3) s(-1)）的AABW消耗（上升流），主要在南纬30度以北。相反，参数化的背风波驱动混合仅在南大洋产生了显著的转变，在那里形成了约3 Sv的AABW，降低了平均密度，但增强了深海水向北流动。基于混合能的理想分布，探讨了远程耗散内潮在补充AABW消耗中的可能作用。主要取决于所选择的垂直结构，这种混合可以驱动1至28 Sv的额外AABW上升流，这突出了更好地约束远程耗散空间分布的必要性。尽管它们具有很大的不确定性，但这些气候转变估计揭示了绝热翻转的定性功能和关键未知因素。
The abyssal ocean is primarily filled by cold, dense waters formed around Antarctica and collectively referred to as Antarctic Bottom Water (AABW). At steady state, AABW must be consumed in the ocean interior at the same rate it is produced, but how and where this consumption is achieved remains poorly understood. Here, estimates of abyssal water mass transformation by geothermal heating and parameterized internal wave-driven mixing are presented. This study uses maps of the energy input to internal waves by tidal and geostrophic motions interacting with topography combined with assumptions about the distribution of energy dissipation to evaluate dianeutral transports induced by breaking internal tides and lee waves. Geothermal transformation is assessed based on a map of geothermal heat fluxes. Under the hypotheses underlying the constructed climatologies of buoyancy fluxes, the authors calculate that locally dissipating internal tides and geothermal heating contribute, respectively, about 8 and 5 Sverdrups (Sv; 1 Sv equivalent to 10(6) m(3) s(-1)) of AABW consumption (upwelling), mostly north of 30 degrees S. In contrast, parameterized lee wave-driven mixing causes significant transformation only in the Southern Ocean, where it forms about 3 Sv of AABW, decreasing the mean density but enhancing the northward flow of abyssal waters. The possible role of remotely dissipating internal tides in complementing AABW consumption is explored based on idealized distributions of mixing energy. Depending mostly on the chosen vertical structure, such mixing could drive 1 to 28 Sv of additional AABW upwelling, highlighting the need to better constrain the spatial distribution of remote dissipation. Though they carry large uncertainties, these climatological transformation estimates shed light on the qualitative functioning and key unknowns of the diabatic overturning.