African Easterly Waves and Tropical Cyclone Genesis
Dr. Michael Atkinson
African easterly waves (AEWs) are key summertime weather systems that prevail over tropical North Africa and the Atlantic. These waves are known to impact daily rainfall over the continent and also tropical cyclones (TC) downstream over tropical Atlantic. Several past studies show that AEW form over East Africa in association with deep convection (REFERENCE). They propagate westwards at about 10 degrees per day and are characterized by wave lengths of 2500-4000km. They grow and amplify over West Africa in association with mid-tropospheric wind stream known as African easterly jet. Daily rainfall and Convective development and strengthening are associated with propagation of AEWs. On average, about 60 waves form and propagate westwards from tropical Africa towards the Atlantic. These waves serve as precursors to TC-genesis (REFERENCE). About half of TCs and about 80% of hurricanes form in association with AEWs (REFERENCE). However, only a small percentage of AEWs are known to spawn TCs over eastern Atlantic. Some AEWs tend to serve as precursors; most don't. We do not know why some trigger TCs and some don't. Starting with a case study, this study investigates the environmental conditions that facilitate AEWs enhancing into tropical cyclones.
Warren, Xavier, "African Easterly Waves and Tropical Cyclone Genesis" (2019). Undergraduate Research and Creative Inquiry Symposia. 158.