Island Wakes in Deep Water

• DOI: 10.1175/jpo3047.1
• Publication Date: 2007-05-01T19:48:16Z
• Authors: Changming Dong; James C. McWilliams; Alexander F. Shch...
• Keywords: Barotropic fluid; Anticyclone; Eddy; Rossby number; Stratification (seeds); Mean flow

Abstract Density stratification and planetary rotation distinguish three-dimensional island wakes significantly from a classical fluid dynamical flow around an obstacle. A numerical model is used to study the formation evolution of idealized in deep water (i.e., with vertical sides surface-intensified upstream flow), focusing on wake instability, coherent vortex formation, mesoscale submesoscale eddy activity. In baseline experiment strong vorticity generation at island, three types instability are evident: centrifugal, barotropic, baroclinic. Sensitivities shown nondimensional parameters: Reynolds number (Re), Rossby (Ro), Burger (Bu). The dependence Re similar its transition turbulence, but contrast contains eddies no matter how large value. When enough, shear layer so narrow that component larger than Coriolis frequency near wake, leading centrifugal anticyclonic side. As Bu decreases size shrinks breadth baroclinic deformation radius, process shifts barotropic instability. For small Ro values, dynamics symmetric respect cyclonic eddies. At intermediate increasingly more robust ones as Ro/Bu increases, for weakens while remain coherent.