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Global patterns of mesoscale eddy properties and diffusivities
Citation
Klocker, A and Abernathey, R, Global patterns of mesoscale eddy properties and diffusivities, Journal of Physical Oceanography, 44, (3) pp. 1030-1046. ISSN 0022-3670 (2014) [Refereed Article]
Copyright Statement
Copyright 2014 American Meteorological Society
DOI: doi:10.1175/JPO-D-13-0159.1
Abstract
Mesoscale eddies play a major role in the transport of tracers in the ocean. Focusing on a sector in the east
Pacific, the authors present estimates of eddy diffusivities derived from kinematic tracer simulations using
satellite-observed velocity fields. Meridional diffusivities are diagnosed, and how they are related to eddy
properties through the mixing length formulation of Ferrari and Nikurashin, which accounts for the suppression
of diffusivity due to eddy propagation relative to the mean flow, is shown. The uniqueness of this
study is that, through systematically varying the zonal-mean flow, a hypothetical unsuppressed diffusivity is
diagnosed. At a given latitude, the unsuppressed diffusivity occurs when the zonal-mean flow equals the eddy
phase speed. This provides an independent estimate of eddy phase propagation, which agrees well with
theoretical arguments. It is also shown that the unsuppressed diffusivity is predicted very well by classical
mixing length theory, that is, that it is proportional to the rms eddy velocity times the observed eddy size, with
a spatially constant mixing efficiency of 0.35. Then, the suppression factor is estimated and it is shown that it
too can be understood quantitatively in terms of easily observed mean flow properties. The authors then
extrapolate from these sector experiments to the global scale, making predictions for the global surface eddy
diffusivity. Together with a prognostic equation for eddy kinetic energy and a theory explaining observed eddy
sizes, these concepts could potentially be used in a closure for eddy diffusivities in coarse-resolution ocean
climate models.
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | eddy mixing properties, diffusivities |
Research Division: | Earth Sciences |
Research Group: | Oceanography |
Research Field: | Physical oceanography |
Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
Objective Group: | Understanding climate change |
Objective Field: | Understanding climate change not elsewhere classified |
UTAS Author: | Klocker, A (Dr Andreas Klocker) |
ID Code: | 91548 |
Year Published: | 2014 |
Web of Science® Times Cited: | 93 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2014-05-21 |
Last Modified: | 2017-11-01 |
Downloads: | 0 |
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