WRF Simulations of Future Saharan Dust Concentrations Across West Africa: Historical and Late 21st Century

Abstract

The Sahara is the largest dust source in the world with individual dust events caused by wind-driven meteorological conditions. The meteorological wind perturbations are multiscaled ranging from convective scale to synoptic scale, leading to uncertainty in future projections of surface dust and transport with Earth System Models (ESMs). We use the Weather Research and Forecasting (WRF) model with 20 km grid spacing forced by the MPI-ESM to examine present-day and late-century dust changes in the presence of SSP126 and SSP585 GHG forcing. Results show higher PM₁₀ concentrations in the SSP126 simulation, but the largest winter and summer season increases occur in the WRF MPI SSP585 simulation. Increases in PM₁₀ concentrations during DJF are linked to higher pressure across North Africa. During JJA, warmer surface conditions increase the vertical transport of dust in the Saharan Air Layer (SAL). In addition, we find a weaker African Easterly Jet (AEJ) at lower latitudes and reductions in lower troposphere relative humidity and precipitation in the Western Sahel from June through August. These climate outcomes would lead to negative health outcomes and increase climate injustice for future populations in West Africa.