How regional SST shapes Saharan Near-Surface Temperature: Sensitivity and Dynamical Mechanisms

Abstract

The Sahara Desert has undergone substantial near-surface warming during the boreal warm season (June–November) in recent decades. Previous studies have suggested that historical and future Saharan warming is largely controlled by sea surface temperature (SST) changes. Here, we assess the sensitivity of Saharan near-surface temperature during the boreal warm season to SST anomalies at individual ocean grid points using Geophysical Fluid Dynamics Laboratory (GFDL) SST-patch experiments. To test the robustness of the results, we further validate the GFDL SST-patch responses using the Community Earth System Model (CESM). Both models consistently show that Saharan near-surface temperature is particularly sensitive to SST anomalies over the Mediterranean Sea, Caribbean Sea, and north Indian Ocean. Warming in the Mediterranean Sea and Caribbean Sea enhances Saharan warming, whereas warming in the north Indian Ocean induces Saharan cooling. The mechanisms underlying these responses are further examined using transient simulations and a potential temperature budget analysis. Results show that anomalous horizontal heat advection dominates the Saharan near-surface temperature response to SST perturbations, regardless of forcing location. Specifically, warming in the Mediterranean Sea and Caribbean Sea induces anomalous warm air advection over the Sahara accompanied by large-scale Rossby wave responses, whereas warming in the north Indian Ocean produces anomalous cold air advection associated with a Gill-type response and an intensified Azores High. These results demonstrate a strong basin dependence of SST impacts on Saharan temperature and underscore the dominant role of atmospheric circulation–driven horizontal heat advection in mediating the Saharan temperature response.