On quartet interactions in the California Current system
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...
| Published in: | Nonlinear Processes in Geophysics |
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| Main Authors: | , , |
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-08-01
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| Online Access: | http://www.nonlin-processes-geophys.net/21/887/2014/npg-21-887-2014.pdf |
| Summary: | 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. |
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| ISSN: | 1023-5809 1607-7946 |