Meteorological Developments of Dust Events in Senegal

Air pollution is responsible for one in nine deaths globally and may get worse over time with the growth of Megacities population. Saharan dust aerosols pose as a natural hazard and can significantly reduce air quality. Little data exists for the meteorological developments of dust storms in the Sahara. I examine two multi-day dust events in Senegal in December 2017 and March 2019. Both storms resulted in hazardous levels of dust impacting the country for numerous days. To determine how these storms formed, I used NCEP data to look at the surface and upper atmosphere feature. This data allowed me to assess the synoptic features around West Africa during the lengths of the storms. I also used the Weather Research and Forecasting (WRF) model to further examine the meteorological events and compare to the NCEP reanalyses. I found that despite similar levels of severity, the two storms were driven by different meteorological features. The 2017 storm was largely driven by a high pressure system moving over the Atlantic, whereas the 2019 storm developed by an extensive trough stretching through Western Africa. I used the deep blue aerosol optical depth layer from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) data to visually determine how the dust transported into Senegal, and from the dust source region in the Sahara. Using the WRF model, we also examined how predicted PM2.5 and PM10 concentrations evolved over the Sahara and were transported into Senegal. A GFS framework is used to evaluate PM concentrations for the fourteen districts for the duration of both storms. With an understanding of dust storms formation, along with the hazard levels of PM2.5 and PM10, the data may contribute to more accurate forecasts in the future, as well as a greater public knowledge on the severity of such storms.