Nonlinear Cascades of Surface Oceanic Geostrophic Kinetic Energy in the Frequency Domain
Abstract
Motivated by the ubiquity of time series in oceanic data, the relative lack of studies of geostrophic turbulence in the frequency domain, and the interest in quantifying the contributions of intrinsic nonlinearities to oceanic frequency spectra, this paper examines the spectra and spectral fluxes of surface oceanic geostrophic flows in the frequency domain. Spectra and spectral fluxes are computed from idealized two-layer quasigeostrophic (QG) turbulence models and realistic ocean general circulation models, as well as from gridded satellite altimeter data. The frequency spectra of the variance of streamfunction (akin to sea surface height) and of geostrophic velocity are qualitatively similar in all of these, with substantial variance extending out to low frequencies. The inverse cascade toward larger length scales documented in calculations of the spectral flux flfk) in the wavenumber k domain. Computations of n(u>) in the realistic model also display an "inverse temporal cascade." In satellite altimeter data, some regions are dominated by an inverse temporal cascade, whereas others exhibit a forward temporal cascade.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2012
- Accession Number
- ADA578082
Entities
People
- Andrew J. Morten
- Brain K. Arbic :robert B.
- Glenn R. Flierl
- James G. Richman
- Jay F. Shriver
Organizations
- United States Naval Research Laboratory