Open AccessDynamics of wind‐forced coherent anticyclones in the open ocean
Author(s) -
Koszalka Inga,
Bracco Annalisa,
McWilliams James C.,
Provenzale Antonello
Publication year - 2009
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009jc005388
Subject(s) - pycnocline , anticyclone , vortex , eddy , geostrophic wind , rossby wave , geology , turbulence , frontogenesis , rossby number , cyclone (programming language) , mechanics , physics , baroclinity , atmospheric sciences , climatology , oceanography , mesoscale meteorology , field programmable gate array , computer science , computer hardware
We numerically study the dynamics of coherent anticyclonic eddies in the ocean interior. For the hydrostatic, rotating, stably stratified turbulence we use a high‐resolution primitive equation model forced by small‐scale winds in an idealized configuration. Many properties of the horizontal motions are found to be similar to those of two‐dimensional and quasi‐geostrophic turbulence. Major differences are a strong cyclone‐anticyclone asymmetry linked to the straining field exerted by vortex Rossby waves, which is also found in shallow water flows, and the complex structure of the vertical velocity field, which we analyze in detail. Locally, the motion can become strongly ageostrophic, and vertical velocities associated with vortices can reach magnitudes and levels of spatial complexity akin to those reported for frontal regions. Transport and mixing properties of the flow field are further investigated by analyzing Lagrangian trajectories. Particles released in the pycnocline undergo large vertical excursions because of the vertical velocities associated to the vortices, with potentially important consequences for marine ecosystem dynamics.