WRF‐CHEM Simulations of Unhealthy PM₁₀ Concentrations During Four Dust Events in Senegal

AbstractWinter season Saharan dust aerosols are transported into West Africa and pose as a natural hazard with individual dust events significantly reducing air quality. We simulate four multi‐day dust events using the Weather, Research and Forecasting Chemistry (WRF‐CHEM) in Senegal during December 2016, December 2017, February 2019, and March 2019. We use Geospatial Informational System mapping to estimate PM10 concentrations for the 14 administrative districts within Senegal. Saharan dust events are evaluated using surface PM10 concentrations at Dakar, Senegal, Moderate Resolution Imaging Spectrometer Aerosol Optical Depth, Aerosol Robotic Network, and the WRF‐CHEM model to evaluate dust concentrations across Senegal. We show that a north to south pressure gradient associated with the southward movement of the Azores high into North Africa are responsible for dust generation and transport into Senegal during 2016 and 2017. Conversely, Saharan depressions moving across the Sahara Desert are responsible for the two high‐impact dust events in February and March of 2019. Based on our analysis, the most severe of the four dust events impacting Senegal occurred in December 2017, with hazardous PM10 concentrations simulated for 7 days affecting an estimated 86% of Senegal's population. Furthermore, the February 2019 dust event occurred during the presidential elections, potentially exposing many voters to poor air quality. A network of surface dust observations and dust forecasts are critical for protecting the Sahelian public from dangerous dust events. Together, they allow for preventative measures to minimize harmful PM10 concentration exposure, especially for children under 5, the elderly, and those with existing respiratory and cardiovascular diseases.