Oscillating, stratified boundary layers driven by surface temperature variations

Abstract

A classification of types of stratified, rotating boundary layers, driven by periodic forcing is presented. The dynamics of such flow is shown to depend on the product of the Ekman number and a stratification parameter and on the ratio of the forcing frequency to the Coriolis frequency. Certain asymptotic solutions are presented for atmospheric values of the stratification parameter and mid-latitude-synoptic and diurnal values of the nondimensional forcing frequency. For the case of flow driven by diurnally varying, differential surface heating, the thermal forcing is absorbed primarily by the Stokes part of the flow which in turn generates an Ekman layer and associated vertical motion. This Ekman pumping induces adjustments in an overlying oscillating Lineykin layer.