Stationary Waves on a Sphere: Sensitivity to Thermal Feedback

Abstract

Abstract Thermal forcing feedback is proposed to be an important mechanism in middle and high latitudes in determining the low-frequency variability of the stationary wave structure. The total diabatic heating in the atmosphere is not due solely to the fixed longitudinally varying heat sources but also depends on the flow field itself. As a first approximation to this complex process, a heat flux which is proportional to the low-level temperature of the atmosphere is incorporated into a multi-level. steady-state, linear primitive equation model on a sphere. It is shown that, for deep vertical distributions of middle- and high-latitude diabatic heating, the inclusion of this feedback significantly amplifies the local and remote response. For shallow vertical distributions of middle- and high-latitude heat sources, the significant increase of amplitude is confined to the local response while the remote response is damped. The remote response due to tropical forcing is dramatically damped regardless of the v...