Trains of African Easterly Waves and Their Relationship to Tropical Cyclone Genesis in the Eastern Atlantic

AbstractIn this study, the relationship between trains of African easterly waves (AEWs) and downstream tropical cyclogenesisis studied. Based on 19 summer seasons (July–September from 1990 to 2008) of ERA-Interim reanalysis fields and brightness temperaturefrom the Cloud User Archive, the signature of AEW troughs and embedded convection are tracked from the West Africancoast to the central Atlantic. The tracked systems are separated into four groups: (i) systems originating from the north zone of the midtropospheric African easterly jet(AEJ), (ii) those coming from the south part of AEJ, (iii) systems that are associated with a downstream trough located around 2000 km westward (termed DUO systems), and (iv) those that are not associated with such a close downstream trough (termed SOLO systems).By monitoring the embedded 700-hPa-filtered relative vorticity and 850-hPa wind convergence anomaly associated with these families along their trajectories, it is shown that the DUO generally have stronger dynam...