Articles | Volume 21, issue 4
Nonlin. Processes Geophys., 21, 887–900, 2014
https://doi.org/10.5194/npg-21-887-2014
Nonlin. Processes Geophys., 21, 887–900, 2014
https://doi.org/10.5194/npg-21-887-2014

Research article 29 Aug 2014

Research article | 29 Aug 2014

On quartet interactions in the California Current system

L. M. Ivanov1, C. A. Collins1,2, and T. M. Margolina1 L. M. Ivanov et al.
  • 1Naval Postgraduate School, Monterey, California, USA
  • 2Moss Landing Marine Laboratories, Moss Landing, California, USA

Abstract. Sea surface height (SSH) altimetry observations for 1992 to 2009 off 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 biannual oscillations and quasi-zonal jets. Two types of quartets were identified: those composed of scales corresponding to (a) quasi-zonal jets, annual and semiannual Rossby waves and mesoscale eddies, and (b) biannual oscillations, semiannual Rossby waves and mesoscale eddies. The spectral centroid regularly shifted into the domain of low-order modes. However, the spectrum of SSHs does not demonstrate a power behavior. This says that the classical inverse cascade is absent. For a case with bottom friction, quartet instability required the existence of a certain level of dissipativity in the flow.