Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

Journal Article · Tue Dec 15 04:00:00 EST 2015 · Physics of Fluids (1994)

DOI:https://doi.org/10.1063/1.4936869· OSTI ID:22482458

Sugimoto, Norihiko ^[1]

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1. Department of Physics, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa 223-8521 (Japan)

Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

• OSTI ID: 22482458
• Journal Information: Physics of Fluids (1994), Journal Name: Physics of Fluids (1994) Journal Issue: 12 Vol. 27; ISSN 1070-6631; ISSN PHFLE6
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCURACY
ANTICYCLONES
ASYMMETRY
AXIAL SYMMETRY
CYCLONES
GRAVITY WAVES
MOMENT OF INERTIA
NUMERICAL ANALYSIS
ROTATION
VORTICES
WATER