The Non-Linear Response of a Two-Layer, Baroclinic Ocean to a Stationary, Axially-Symmetric Hurricane. Part II. Upwelling and Mixing Induced by Momentum Transfer

Abstract

This paper is a continuation of a theoretical description of upwelling and mixing induced in a stratified, rotating, two-layer ocean by momentum transfer from an intense, stationary, axially-symmetric atmospheric vortex. A second model which includes mixing is considered. The dynamic internal response of the ocean is assumed to be axially symmetric which permits consideration of the solution in two independent variables, radial distance and time. Numerical integration via the method of characteristics is utilized to obtain values of depth-averaged radial and tangential velocities, depth of the upper layer, and density contrast for a period of two days. Transfer of momentum between the air and the sea and between the upper and lower layers of the ocean is included. Transfer of heat and salt between the two ocean layers is simulated. Transfer of heat and moisture with the atmosphere is not considered. The mechanism of energy transfer to and from the atmosphere and to and from the lower layer is examined in detail. This indicates that the total energy varies only with the inertial period. The energy associated with the effect of mixing is an order of magnitude smaller than that associated with turbulent dissipation. However, turbulent mixing of heat and salt modifies the density structure throughout the wind-forced region of the ocean, while intense upwelling is confined to within twice the radius of maximum hurricane winds.