Future projection of the African easterly waves in a high-resolution AGCM

African Easterly Waves (AEWs) are a significant control of West African rainfall and the associated Mesoscale Convective Systems (MCSs) and squall lines embedded within them. More than 40% of the total MCSs over the region are associated with AEWs and these MCSs account for approximately 80% of the total annual rainfall over the Sahel. Approximately 60% of all Atlantic hurricanes and 80% of major hurricanes have their genesis associated with AEWs. Simulating the features of AEWs, such as their westward propagation off the east Atlantic coast, is challenging for coarse-resolution climate models. In this study, we use High-Resolution Atmospheric Model (HiRAM) to simulate AEWs and analyze their future projections by the end of the 21st century. The simulations are performed globally at a horizontal resolution of 25km. The model uses shallow convective parameterization for moist convection and stratiform cloudiness. Future projections are conducted using representative concentration pathway 8.5. AEWs are separated with respect to their periods as 3–5 and 6–9-day period AEWs, and bandpass filtering is used to filter the waves from the mean flow. HiRAM simulates the structure and propagation of the waves well; however, it tends to overestimate the associated precipitation. In the future, the AEW precipitation and intensity of the circulation will considerably increase. The northward extent of the AEW track also shows a significant increase in the future. Enhanced baroclinic overturning and eddy available potential energy generated due to diabatic heating is also observed in the future.