A Model of Baroclinic Instability and Waves between the Ventilated Gyre and the Shadow Zone of the North Atlantic Ocean

Abstract

Distributions of eddy kinetic energy in the North Atlantic Ocean show that enhanced mesoscale activity exists in the Cape Verde Frontal Zone (the eastern part of the Central Water Boundary). This variability and its associated length and time scales are investigated with a three-dimensional numerical model that uses primitive equations in a hybrid (quasi-isopycnic) coordinate system in which the Coriolis parameter varies linearly. The model has a horizontal resolution of 15.625 km in 11 isopycnic layers. The domain comprises a 1000-km square centered at 20 ^circ N having idealized bottom topography and zonally periodic boundary conditions. A zonal, geostrophically balanced jet representing an undisturbed Canary Current is used for the initial conditions. Potential vorticity is used to distinguish between water masses that are reconstructed from a hydrographic section. The growth of meanders is stimulated by an ageostrophic perturbation field consisting of white noise. Integration is carried out for 200 model days