Sea-Air Interaction: A Simplified Model

Abstract

In the long range prediction of the large scale motion of the atmosphere it is essential to prescribe realistic lower boundary conditions over oceans which incorporate the important features of the sea-air interaction. These features include the energy input to the atmosphere arising from the flux of latent heat of the water vapor evaporated from the sea as a result of the absorption of solar energy in the upper levels of the ocean. In addition, one must include the braking action of the wavy sea surface on the surface winds. For a simplified model incorporating these features a steady model is postulated where advection effects are neglected. The domain considered includes the atmospheric surface boundary layer and the upper levels of the sea down to a depth below the diurnal thermocline. In the surface boundary layer the shear stress and the heat flux are considered invariant, and the turbulent diffusivities proposed by Pandolfo are used. For the oceans we essentially use the model due to Munk and Anderson in which a simplification is carried out which decouples the energy equation from the momentum equations and permits a direct determination of the sensible heat flux in the ocean from the former equation. A sample calculation is carried out and a procedure is given to incorporate the results as a lower boundary condition for the initial value problem for the prediction of the large scale atmospheric motion.