Spatio-Temporal Trends of Dust Storms Drivers and Their Role in the Decline of Dust Activity over North Africa

This study investigates the spatiotemporal trends of key environmental drivers of dust emission over North Africa especially precipitation, surface wind speed, low vegetation leaf area index (LAI), and the Saharan Heat Low (SHL). Using reanalysis data spanning the past four decades (1984-2023), we analyze the spatial trends and assess their statistical significance. The aim is to evaluate how long-term changes in these local meteorological drivers may have contributed to the observed decline in dust activity over North Africa. Results reveal a widespread increase in precipitation and LAI, particularly across the Sahel region (10˚N-20˚N), suggesting enhanced surface wetness and vegetation cover that act to suppress dust mobilization. Simultaneously, a significant negative trend in 10 m wind speed was observed across both the Sahel and parts of Sahara, limiting the surface wind stress required for dust uplift. In contrast, the SHL exhibited a notable intensification and westward expansion, especially over the southern Sahara. Although SHL strengthening is typically associated with increased dust activity, our findings point to a more nuanced role, wherein its recent expansion coincides with broader dust-suppressing environmental trends. These co-evolving changes provide a compelling mechanistic explanation for the observed decline in North African dust activity over recent decades and enhance our understanding and climate models capabilities related to dust activity over North Africa.