INFLUENCE OF STABLE STRATIFICATION ON THE THERMALLY DRIVEN TROPICAL BOUNDARY LAYER.

Abstract

Simple linearized models of the steady, thermally driven, axially symmetric motion of a stably stratified fluid on a rotating sphere are used to study the near-equator behavior of the boundary layer. It is found that the inclusion of the stratification introduces the natural horizontal length scale L of the geometric mean of the radius of the earth and a global Rossby radius of deformation. The tropical boundary layer is found to have constant finite depth over a length scale O (L) from the equator through pressure boundary layering. The baroclinicity of the fluid is important for the interior flow also for a length scale O (L) from the equator. Therefore, the inclusion of stable stratification is likely to be necessary in simple models describing features of the intertropical convergence zone. An approximate solution to the boundary layer equations using a method devised by H. L. Kuo are compared to ″exact″ solutions. Kuo's method is found to introduce significant errors.