Energetics of Bottom Ekman Layers during Buoyancy ArrestSource: Journal of Physical Oceanography:;2015:;Volume( 045 ):;issue: 012::page 3099DOI: 10.1175/JPO-D-15-0041.1Publisher: American Meteorological Society
Abstract: urbulent bottom Ekman layers are among the most important energy conversion sites in the ocean. Their energetics are notoriously complex, in particular near sloping topography, where the feedback between cross-slope Ekman transports, buoyancy forcing, and mixing affects the energy budget in ways that are not well understood. Here, the authors attempt to clarify the energy pathways and different routes to mixing, using a combined theoretical and modeling approach. The analysis is based on a newly developed energy flux diagram for turbulent Ekman layers near sloping topography that allows for an exact definition of the different energy reservoirs and energy pathways. Using a second-moment turbulence model, it is shown that mixing efficiencies increase for increasing slope angle and interior stratification, but do not exceed the threshold of 5% except for very steep slopes, where the canonical value of 20% may be reached. Available potential energy generated by cross-slope advection may equal up to 70% of the energy lost to dissipation for upwelling-favorable flow, and up to 40% for downwelling-favorable flow.
|
Collections
Show full item record
contributor author | Umlauf, Lars | |
contributor author | Smyth, William D. | |
contributor author | Moum, James N. | |
date accessioned | 2017-06-09T17:21:23Z | |
date available | 2017-06-09T17:21:23Z | |
date copyright | 2015/12/01 | |
date issued | 2015 | |
identifier issn | 0022-3670 | |
identifier other | ams-83735.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4226993 | |
description abstract | urbulent bottom Ekman layers are among the most important energy conversion sites in the ocean. Their energetics are notoriously complex, in particular near sloping topography, where the feedback between cross-slope Ekman transports, buoyancy forcing, and mixing affects the energy budget in ways that are not well understood. Here, the authors attempt to clarify the energy pathways and different routes to mixing, using a combined theoretical and modeling approach. The analysis is based on a newly developed energy flux diagram for turbulent Ekman layers near sloping topography that allows for an exact definition of the different energy reservoirs and energy pathways. Using a second-moment turbulence model, it is shown that mixing efficiencies increase for increasing slope angle and interior stratification, but do not exceed the threshold of 5% except for very steep slopes, where the canonical value of 20% may be reached. Available potential energy generated by cross-slope advection may equal up to 70% of the energy lost to dissipation for upwelling-favorable flow, and up to 40% for downwelling-favorable flow. | |
publisher | American Meteorological Society | |
title | Energetics of Bottom Ekman Layers during Buoyancy Arrest | |
type | Journal Paper | |
journal volume | 45 | |
journal issue | 12 | |
journal title | Journal of Physical Oceanography | |
identifier doi | 10.1175/JPO-D-15-0041.1 | |
journal fristpage | 3099 | |
journal lastpage | 3117 | |
tree | Journal of Physical Oceanography:;2015:;Volume( 045 ):;issue: 012 | |
contenttype | Fulltext |