Having completed a two-year, real-time evaluation and diagnosis of the distribution of potential vorticity (PV) in the tropical North Atlantic, we present evidence that suggests that not all African easterly waves (AEWs) are Rossby wave-like structures as commonly described in the literature. Rather, AEWs appear in global analyses as maxima in PV with an attendant set of closed PV contours. Recognition of this PV distribution associated with AEW sheds new insight into theis propagation and development characteristics. Indeed, the degree to which these disturbances are linear Rossby waves has important implications regarding the mechanisms for their further development.

Based on the aforementioned structure of AEWs, we present the results of an investigation of the role that the PV "superposition mechanism" may play as a mechanism for the transformation of AEWs into tropical cyclones.