Easterly Waves and Perturbations, a Reappraisal

Abstract

Analyses of tropical perturbations in the Atlantic Region (commonly referred to as easterly waves), utilizing observations from meteorological satellites, reveal that five distinctly different cloud distributions occur. These patterns are both linear (similar to the classic Riehl model of the easterly wave) and vortical. The vortical patterns appear roost frequently and are often related to a closed cyclonic circulation in the mid-troposphere. Calculations of the horizontal and vertical distributions of divergence and vorticity indicative of the mid-tropospheric circulation in an intense disturbance are shown.