Instability of surface-temperature filaments in strain and shear

Harvey, B. J. ORCID: https://orcid.org/0000-0002-6510-8181 and Ambaum, M. H. P. ORCID: https://orcid.org/0000-0002-6824-8083 (2010) Instability of surface-temperature filaments in strain and shear. Quarterly Journal of the Royal Meteorological Society, 136 (651). pp. 1506-1513. ISSN 1477-870X doi: 10.1002/qj.651

Abstract/Summary

The effects of uniform straining and shearing on the stability of a surface quasi-geostrophic temperature filament are investigated. Straining is shown to stabilize perturbations for wide filaments but only for a finite time until the filament thins to a critical width, after which some perturbations can grow. No filament can be stabilized in practice, since there are perturbations that can grow large for any strain rate. The optimally growing perturbations, defined as solutions that reach a certain threshold amplitude first, are found numerically for a wide range of parameter values. The radii of the vortices formed through nonlinear roll-up are found to be proportional to θ/s, where θ is the temperature anomaly of the filament and s the strain rate, and are not dependent on the initial size of the filament. Shearing is shown to reduce the normal-mode growth rates, but it cannot stabilize them completely when there are temperature discontinuities in the basic state; smooth filaments can be stabilized completely by shearing and a simple scaling argument provides the shear rate required. Copyright © 2010 Royal Meteorological Society

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/7594
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Uncontrolled Keywords	surface quasi-geostrophic dynamics;stability;turbulence
Publisher	Royal Meteorological Society
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