Abstract
Anomalously large values of the Reynolds stress (downstream component) obtained from measurements analysed by Angell are explained as being associated with changes in velocity at the top of a deepening planetary boundary layer. The proposed explanation is tested both by a simple interfacial velocity-jump model, and by a detailed three-dimensional numerical model. A method of parameterizing the complicated vertical profiles of momentum flux is proposed for use within large scale, multi-level circulation models.
