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Title: Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach

Abstract

A coarse-graining framework is implemented to analyze nonlinear processes, measure energy transfer rates, and map out the energy pathways from simulated global ocean data. Traditional tools to measure the energy cascade from turbulence theory, such as spectral flux or spectral transfer, rely on the assumption of statistical homogeneity or at least a large separation between the scales of motion and the scales of statistical inhomogeneity. The coarse-graining framework allows for probing the fully nonlinear dynamics simultaneously in scale and in space and is not restricted by those assumptions. This paper describes how the framework can be applied to ocean flows. Energy transfer between scales is not unique because of a gauge freedom. Here, it is argued that a Galilean-invariant subfilter-scale (SFS) flux is a suitable quantity to properly measure energy scale transfer in the ocean. It is shown that the SFS definition can yield answers that are qualitatively different from traditional measures that conflate spatial transport with the scale transfer of energy. The paper presents geographic maps of the energy scale transfer that are both local in space and allow quasi-spectral, or scale-by-scale, dynamics to be diagnosed. Utilizing a strongly eddying simulation of flow in the North Atlantic Ocean, itmore » is found that an upscale energy transfer does not hold everywhere. Indeed certain regions near the Gulf Stream and in the Equatorial Countercurrent have a marked downscale transfer. Nevertheless, on average an upscale transfer is a reasonable mean description of the extratropical energy scale transfer over regions of O(10 3 ) km in size.« less

Authors:
 [1];  [2];  [3]
  1. Department of Mechanical Engineering, and, Laboratory for Laser Energetics, University of Rochester, Rochester, New York
  2. Computational Physics and Methods (CCS-2), Los Alamos National Laboratory, Los Alamos, New Mexico
  3. College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1418186
Alternate Identifier(s):
OSTI ID: 1411355
Report Number(s):
[LA-UR-17-24117]
[Journal ID: ISSN 0022-3670]
Grant/Contract Number:  
[SC0014318; NA0001944; 20150568ER; HiLAT project; AC52-06NA25396]
Resource Type:
Published Article
Journal Name:
Journal of Physical Oceanography
Additional Journal Information:
[Journal Name: Journal of Physical Oceanography Journal Volume: 48 Journal Issue: 2]; Journal ID: ISSN 0022-3670
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Earth Sciences

Citation Formats

Aluie, Hussein, Hecht, Matthew, and Vallis, Geoffrey K. Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach. United States: N. p., 2018. Web. doi:10.1175/JPO-D-17-0100.1.
Aluie, Hussein, Hecht, Matthew, & Vallis, Geoffrey K. Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach. United States. doi:10.1175/JPO-D-17-0100.1.
Aluie, Hussein, Hecht, Matthew, and Vallis, Geoffrey K. Thu . "Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach". United States. doi:10.1175/JPO-D-17-0100.1.
@article{osti_1418186,
title = {Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach},
author = {Aluie, Hussein and Hecht, Matthew and Vallis, Geoffrey K.},
abstractNote = {A coarse-graining framework is implemented to analyze nonlinear processes, measure energy transfer rates, and map out the energy pathways from simulated global ocean data. Traditional tools to measure the energy cascade from turbulence theory, such as spectral flux or spectral transfer, rely on the assumption of statistical homogeneity or at least a large separation between the scales of motion and the scales of statistical inhomogeneity. The coarse-graining framework allows for probing the fully nonlinear dynamics simultaneously in scale and in space and is not restricted by those assumptions. This paper describes how the framework can be applied to ocean flows. Energy transfer between scales is not unique because of a gauge freedom. Here, it is argued that a Galilean-invariant subfilter-scale (SFS) flux is a suitable quantity to properly measure energy scale transfer in the ocean. It is shown that the SFS definition can yield answers that are qualitatively different from traditional measures that conflate spatial transport with the scale transfer of energy. The paper presents geographic maps of the energy scale transfer that are both local in space and allow quasi-spectral, or scale-by-scale, dynamics to be diagnosed. Utilizing a strongly eddying simulation of flow in the North Atlantic Ocean, it is found that an upscale energy transfer does not hold everywhere. Indeed certain regions near the Gulf Stream and in the Equatorial Countercurrent have a marked downscale transfer. Nevertheless, on average an upscale transfer is a reasonable mean description of the extratropical energy scale transfer over regions of O(10 3 ) km in size.},
doi = {10.1175/JPO-D-17-0100.1},
journal = {Journal of Physical Oceanography},
number = [2],
volume = [48],
place = {United States},
year = {2018},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1175/JPO-D-17-0100.1

Citation Metrics:
Cited by: 6 works
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Works referenced in this record:

Argo float data and metadata from Global Data Assembly Centre (Argo GDAC)
dataset, January 2018

  • Fumihiko, Akazawa; Turki, Alraddadi; Pascual, Ananda
  • DOI: 10.17882/42182

Argo float data and metadata from Global Data Assembly Centre (Argo GDAC)
dataset, January 2018

  • Fumihiko, Akazawa; Turki, Alraddadi; Pascual, Ananda
  • DOI: 10.17882/42182

    Works referencing / citing this record:

    Argo float data and metadata from Global Data Assembly Centre (Argo GDAC)
    dataset, January 2018

    • Fumihiko, Akazawa; Turki, Alraddadi; Pascual, Ananda
    • DOI: 10.17882/42182

    Baropycnal Work: A Mechanism for Energy Transfer across Scales
    journal, May 2019