The Relationship Between African Easterly Waves and the Atlantic ITCZ: Structural Insights from ORCESTRA

African Easterly Waves (AEWs) are the dominant synoptic-scale tropical disturbance in the boreal summer Atlantic. However, direct three-dimensional observations of these waves and their modulation of the Intertropical Convergence Zone (ITCZ) remain limited.

Observations from the Eastern Atlantic leg of ORCESTRA are used to characterize the mean vertical and horizontal structure of seven robust AEWs in a wave-relative framework. The observations reveal coherent vertical wind and moisture structures, with upstream–downstream asymmetries relevant for both synoptic-scale organization and deep convection. These results motivate a focused investigation of how AEWs influence the structure and organization of the ITCZ.

We test the hypothesis that AEWs play a central role in constraining ITCZ structure during boreal summer. Based on the observed AEW structure, we hypothesize that wave-modulated moisture distributions and gradients influence the organization of deep convection within the ITCZ. Large-eddy simulations conducted over the campaign period are compared with the observations to assess the representation of AEWs and to further explore AEW–ITCZ interactions.