On modulation instability in a system of jets, waves and eddies off California
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Authors
Ivanov, L.M.
Collins, C.A.
Margolina, T.
Subjects
Advisors
Date of Issue
2014-02-20
Date
February 20, 2014
Publisher
Copernicus Publications
Language
Abstract
SSH altimetry observations for 1992 to 2009 off Central and Southern California are
used to show that observed quasi-zonal jets were likely driven by near-resonance interactions
between different scales of the flow. Quartet (modulational) instability dominated and caused non-local transfer of energy from waves and eddies to bi-annual
oscillations and quasi-zonal jets. The total number of quartets induced off California
was approximately 10 times larger than the number of existing triads, and quartet amplitudes
in general were larger than triad amplitudes. The spectral centroid regularly
shifted into the domain of low-order modes. Local “negative” viscosity probably did not generate a classical inverse cascade because the spectrum of SSHs did not demonstrate
power behavior. Two types of quartets were identified: (a) quasi-zonal jets, annual
and semi-annual Rossby waves and eddies, and (b) bi-annual oscillations, semiannual
Rossby waves and eddies. For a case with bottom friction, quartet instability
required the existence of a certain level of dissipativity in the flow.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.5194/npgd-1-97-2014
Discussion Paper
Discussion Paper
Series/Report No
Department
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
NSF grant OCE-0827527 (OCE-0827160)
Funder
NSF grant OCE-0827527 (OCE-0827160)
Format
33 p.
Citation
Ivanov, L. M., C. A. Collins, and T. Margolina. "On modulation instability in a system of jets, waves and eddies off California." Nonlinear Processes in Geophysics Discussions 1 (2014): 97-129.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.