The secondary circulation associated with a vertically aligned planetary wave critical line

An analytic model of the secondary circulation associated with a vertically aligned, energy absorbing, planetary wave critical line shows that strong zonal mean vertical motions and heating (or cooling) can develop even though no eddy transport of heat occurs. The type of secondary circulation which develops around a vertically aligned critical line may provide a mechanism for stratosphere-troposphere exchange of air. The model predictions are discussed with reference to the 76/77 sudden warming.