Direct Evidence of an Oceanic Inverse Kinetic Energy Cascade from Satellite AltimetrySource: Journal of Physical Oceanography:;2005:;Volume( 035 ):;issue: 009::page 1650DOI: 10.1175/JPO2771.1Publisher: American Meteorological Society
Abstract: Sea surface height measurements from satellites reveal the turbulent properties of the South Pacific Ocean surface geostrophic circulation, both supporting and challenging different aspects of geostrophic turbulence theory. A near-universal shape of the spectral kinetic energy flux is found and provides direct evidence of a source of kinetic energy near to or smaller than the deformation radius, consistent with linear instability theory. The spectral kinetic energy flux also reveals a net inverse cascade (i.e., a cascade to larger spatial scale), consistent with two-dimensional turbulence phenomenology. However, stratified geostrophic turbulence theory predicts an inverse cascade for the barotropic mode only; energy in the large-scale baroclinic modes undergoes a direct cascade toward the first-mode deformation scale. Thus if the surface geostrophic flow is predominately the first baroclinic mode, as expected for oceanic stratification profiles, then the observed inverse cascade contradicts geostrophic turbulence theory. The latter interpretation is argued for. Furthermore, and consistent with this interpretation, the inverse cascade arrest scale does not follow the Rhines arrest scale, as one would expect for the barotropic mode. A tentative revision of theory is proposed that would resolve the conflicts; however, further observations and idealized modeling experiments are needed to confirm, or refute, the revision. It is noted that no inertial range was found for the inverse cascade range of the spectrum, implying inertial range scaling, such as the established K?5/3 slope in the spectral kinetic energy density plot, is not applicable to the surface geostrophic flow.
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contributor author | Scott, Robert B. | |
contributor author | Wang, Faming | |
date accessioned | 2017-06-09T17:17:52Z | |
date available | 2017-06-09T17:17:52Z | |
date copyright | 2005/09/01 | |
date issued | 2005 | |
identifier issn | 0022-3670 | |
identifier other | ams-82649.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4225786 | |
description abstract | Sea surface height measurements from satellites reveal the turbulent properties of the South Pacific Ocean surface geostrophic circulation, both supporting and challenging different aspects of geostrophic turbulence theory. A near-universal shape of the spectral kinetic energy flux is found and provides direct evidence of a source of kinetic energy near to or smaller than the deformation radius, consistent with linear instability theory. The spectral kinetic energy flux also reveals a net inverse cascade (i.e., a cascade to larger spatial scale), consistent with two-dimensional turbulence phenomenology. However, stratified geostrophic turbulence theory predicts an inverse cascade for the barotropic mode only; energy in the large-scale baroclinic modes undergoes a direct cascade toward the first-mode deformation scale. Thus if the surface geostrophic flow is predominately the first baroclinic mode, as expected for oceanic stratification profiles, then the observed inverse cascade contradicts geostrophic turbulence theory. The latter interpretation is argued for. Furthermore, and consistent with this interpretation, the inverse cascade arrest scale does not follow the Rhines arrest scale, as one would expect for the barotropic mode. A tentative revision of theory is proposed that would resolve the conflicts; however, further observations and idealized modeling experiments are needed to confirm, or refute, the revision. It is noted that no inertial range was found for the inverse cascade range of the spectrum, implying inertial range scaling, such as the established K?5/3 slope in the spectral kinetic energy density plot, is not applicable to the surface geostrophic flow. | |
publisher | American Meteorological Society | |
title | Direct Evidence of an Oceanic Inverse Kinetic Energy Cascade from Satellite Altimetry | |
type | Journal Paper | |
journal volume | 35 | |
journal issue | 9 | |
journal title | Journal of Physical Oceanography | |
identifier doi | 10.1175/JPO2771.1 | |
journal fristpage | 1650 | |
journal lastpage | 1666 | |
tree | Journal of Physical Oceanography:;2005:;Volume( 035 ):;issue: 009 | |
contenttype | Fulltext |