气候变化领域集成服务门户(CCPortal): Mesoscale Eddy Dissipation by a “Zoo” of Submesoscale Processes at a Western Boundary

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DOI	10.1029/2020JC016246
	Mesoscale Eddy Dissipation by a “Zoo” of Submesoscale Processes at a Western Boundary
	Evans D.G.; Frajka-Williams E.; Naveira Garabato A.C.; Polzin K.L.; Forryan A.
发表日期	2020
ISSN	21699275
卷号	125 期号:11
英文摘要	Mesoscale eddies are ubiquitous dynamical features that tend to propagate westward and disappear along ocean western boundaries. Using a multiscale observational study, we assess the extent to which eddies dissipate via a direct cascade of energy at a western boundary. We analyze data from a ship-based microstructure and velocity survey, and an 18-month mooring deployment, to document the dissipation of energy in anticyclonic and cyclonic eddies impinging on the topographic slope east of the Bahamas, in the North Atlantic Ocean. These observations reveal high levels of turbulence where the steep and rough topographic slope modified the intensified northward flow associated with, in particular, anticyclonic eddies. Elevated dissipation was observed both near-bottom and at mid depths (200–800 m). Near-bottom turbulence occurred in the lee of a protruding escarpment, where elevated Froude numbers suggest hydraulic control. Energy was also radiated in the form of upward-propagating internal waves. Elevated dissipation at mid depths occurred in regions of strong vertical shear, where the topographic slope modified the vertical structure of the northward eddy flow. Here, low Richardson numbers and a local change in the isopycnal gradient of potential vorticity (PV) suggest that the elevated dissipation was associated with horizontal shear instability. Elevated mid-depth dissipation was also induced by topographic steering of the flow. This led to large anticyclonic vorticity and negative PV adjacent to the topographic slope, suggesting that centrifugal instability underpinned the local enhancement in dissipation. Our results provide a mechanistic benchmark for the realistic representation of eddy dissipation in ocean models. © 2020. The Authors.
英文关键词	direct energy cascade; eddy-topography interactions; energy; instability; mesoscale eddies; turbulence
语种	英语
来源期刊	Journal of Geophysical Research: Oceans
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186603
作者单位	National Oceanography Centre, Southampton, United Kingdom; Ocean and Earth Science, University of Southampton, Southampton, United Kingdom; Woods Hole Oceanographic Institution, Woods HoleMA, United States
推荐引用方式 GB/T 7714	Evans D.G.,Frajka-Williams E.,Naveira Garabato A.C.,等. Mesoscale Eddy Dissipation by a “Zoo” of Submesoscale Processes at a Western Boundary[J],2020,125(11).
APA	Evans D.G.,Frajka-Williams E.,Naveira Garabato A.C.,Polzin K.L.,&Forryan A..(2020).Mesoscale Eddy Dissipation by a “Zoo” of Submesoscale Processes at a Western Boundary.Journal of Geophysical Research: Oceans,125(11).
MLA	Evans D.G.,et al."Mesoscale Eddy Dissipation by a “Zoo” of Submesoscale Processes at a Western Boundary".Journal of Geophysical Research: Oceans 125.11(2020).