Seasonality of eddy kinetic energy in an eddy permitting global climate model

Takaya Uchida, Ryan Abernathey, Kendall Shafer-Smith

Research output: Contribution to journalArticle

Abstract

We examine the seasonal cycle of upper-ocean mesoscale turbulence in a high resolution CESM climate simulation. The ocean model component (POP) has 0.1° resolution, mesoscale resolving at low and middle latitudes. Seasonally and regionally resolved wavenumber power spectra are calculated for sea-surface eddy kinetic energy (EKE). Although the interpretation of the spectral slopes in terms of turbulence theory is complicated by the strong presence of dissipation and the narrow inertial range, the EKE spectra consistently show higher power at small scales during winter throughout the ocean. Potential hypotheses for this seasonality are investigated. Diagnostics of baroclinc energy conversion rates and evidence from linear quasigeostrophic stability analysis indicate that seasonally varying mixed-layer instability is responsible for the seasonality in EKE. The ability of this climate model, which is not considered submesoscale resolving, to produce mixed layer instability although damped by dissipation, demonstrates the ubiquity and robustness of this process for modulating upper ocean EKE.

Original languageEnglish (US)
Pages (from-to)41-58
Number of pages18
JournalOcean Modelling
Volume118
DOIs
StatePublished - Oct 1 2017

Fingerprint

Climate models
Kinetic energy
kinetic energy
seasonality
global climate
climate modeling
eddy
upper ocean
mixed layer
dissipation
Turbulence
turbulence
Linear stability analysis
ocean
Power spectrum
Energy conversion
stability analysis
sea surface
winter
climate

Keywords

  • Baroclinic instability
  • Linear stability analysis
  • Mesoscale turbulence
  • Seasonality
  • Wavenumber spectra

ASJC Scopus subject areas

  • Oceanography
  • Computer Science (miscellaneous)
  • Geotechnical Engineering and Engineering Geology
  • Atmospheric Science

Cite this

Seasonality of eddy kinetic energy in an eddy permitting global climate model. / Uchida, Takaya; Abernathey, Ryan; Shafer-Smith, Kendall.

In: Ocean Modelling, Vol. 118, 01.10.2017, p. 41-58.

Research output: Contribution to journalArticle

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AB - We examine the seasonal cycle of upper-ocean mesoscale turbulence in a high resolution CESM climate simulation. The ocean model component (POP) has 0.1° resolution, mesoscale resolving at low and middle latitudes. Seasonally and regionally resolved wavenumber power spectra are calculated for sea-surface eddy kinetic energy (EKE). Although the interpretation of the spectral slopes in terms of turbulence theory is complicated by the strong presence of dissipation and the narrow inertial range, the EKE spectra consistently show higher power at small scales during winter throughout the ocean. Potential hypotheses for this seasonality are investigated. Diagnostics of baroclinc energy conversion rates and evidence from linear quasigeostrophic stability analysis indicate that seasonally varying mixed-layer instability is responsible for the seasonality in EKE. The ability of this climate model, which is not considered submesoscale resolving, to produce mixed layer instability although damped by dissipation, demonstrates the ubiquity and robustness of this process for modulating upper ocean EKE.

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