African Easterly Jets and Surface Thermal Heating Responses to Climate Change Over Central Africa in CMIP6 Models

The African Easterly Jets (AEJs) are key mid-tropospheric circulation features of the Pan-African subtropical climate system. They consist of two distinct easterly features: the northern jet (AEJ-N), centered over the Sahel in the Northern Hemisphere, and the southern jet (AEJ-S), located over Southern Africa in the Southern Hemisphere. Dynamically linked to atmospheric thermal structures and moisture, their future dynamics remain unclear. We use CMIP6 models to investigate the influence of climate forcing on AEJ representation and explore their relationship with atmospheric thermal heating under SSP585 and SSP245. Results show that under the SSP585 far future (2071–2100) scenario, the AEJ-N shows an eastward shift in its entrance region, consistent with historical simulations. Projections indicate substantial variability across models in the AEJ latitudinal location and intensity. From September to November, a northward migration of the AEJ-N and a general weakening of its intensity are observed, particularly in the far future SSP585. While some models project strengthening of the AEJ-N, others project a weakening, resulting in decreasing ensemble mean representation. AEJ-S projections are more robust and consistent. A southward shift and intensification of the AEJ-S is projected under the SSP585 far future scenario, accompanied by reduced inter-model spread. Further analyses of the physical drivers show a strengthening of the surface-to-mid-level thermal gradient in both hemispheres, with stronger inter-model correlations with AEJ-S intensity than for AEJ-N. This indicates a physically consistent AEJ-S response to future warming, especially in the far future scenario SSP585, while the SSP245 scenario shows weaker or less consistent correlation. Some models show inconsistencies between moisture-temperature structure and mid-level wind projections. Overall, the results highlight the complex interplay between atmospheric thermal heating, moisture, and zonal winds in shaping the AEJ under climate change. The contrasting model behaviors highlight the need for further investigation into the mechanisms driving AEJ variability and for improving model physical processes critical for African climate projections.