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DOI | 10.1029/2019GL082458 |
Squeeze Dispersion and the Effective Diapycnal Diffusivity of Oceanic Tracers | |
Wagner, Gregory L.1; Flierl, Glenn1; Ferrari, Raffaele1; Voet, Gunnar2; Carter, Glenn S.3; Alford, Matthew H.2; Girton, James B.4 | |
2019-05-28 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS
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ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2019 |
卷号 | 46期号:10页码:5378-5386 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | We describe a process called "squeeze dispersion" in which the squeezing of oceanic tracer gradients by waves, eddies, and bathymetric flow modulates diapycnal diffusion by centimeter to meter-scale turbulence. Due to squeeze dispersion, the effective diapycnal diffusivity of oceanic tracers is different and typically greater than the average "local" diffusivity, especially when local diffusivity correlates with squeezing. We develop a theory to quantify the effects of squeeze dispersion on diapycnal oceanic transport, finding formulas that connect density-averaged tracer flux, locally measured diffusivity, large-scale oceanic strain, the thickness-weighted average buoyancy gradient, and the effective diffusivity of oceanic tracers. We use this effective diffusivity to interpret observations of abyssal flow through the Samoan Passage reported by Alford et al. (2013, https://doi.org/10.1002/grl.50684) and find that squeezing modulates diapycnal tracer dispersion by factors between 0.5 and 3. Plain Language Summary Turbulent vertical ocean mixing forms a key part of the Earth's climate system by drawing atmospheric carbon and heat into the massive reservoir that is the deep ocean. Quantifying vertical ocean mixing is difficult: vertical mixing is associated with turbulence at the tiny scales of centimeters to meters but affects the entire ocean on the long time scales of decades and centuries. We demonstrate that vertical ocean mixing depends not only on small-scale turbulence, but on the combination of small-scale turbulence and larger-scale motions, such as currents, eddies, and waves similar to the jet streams and hurricanes of the atmosphere. In particular, when a patch of ocean is mixed by small-scale turbulence while being "squeezed" in the vertical at the same time by currents and eddies, the patch ultimately mixes more quickly than the turbulence would cause alone. This means that estimating the total rate of oceanic vertical mixing requires knowledge both of the magnitude of ocean squeezing as well as the intensity of small-scale ocean turbulence. |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000471237500041 |
WOS关键词 | DISSIPATION ; TURBULENCE ; TRANSPORT |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/183404 |
专题 | 气候变化 |
作者单位 | 1.MIT, Earth Atmospher & Planetary Sci, 77 Massachusetts Ave, Cambridge, MA 02139 USA; 2.Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA; 3.Univ Hawaii Manoa, Dept Oceanog, Honolulu, HI 96822 USA; 4.Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA |
推荐引用方式 GB/T 7714 | Wagner, Gregory L.,Flierl, Glenn,Ferrari, Raffaele,et al. Squeeze Dispersion and the Effective Diapycnal Diffusivity of Oceanic Tracers[J]. GEOPHYSICAL RESEARCH LETTERS,2019,46(10):5378-5386. |
APA | Wagner, Gregory L..,Flierl, Glenn.,Ferrari, Raffaele.,Voet, Gunnar.,Carter, Glenn S..,...&Girton, James B..(2019).Squeeze Dispersion and the Effective Diapycnal Diffusivity of Oceanic Tracers.GEOPHYSICAL RESEARCH LETTERS,46(10),5378-5386. |
MLA | Wagner, Gregory L.,et al."Squeeze Dispersion and the Effective Diapycnal Diffusivity of Oceanic Tracers".GEOPHYSICAL RESEARCH LETTERS 46.10(2019):5378-5386. |
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