Investigating the impact of Saharan dust aerosols on analyses and forecasts of African easterly waves by constraining aerosol effects in radiance data assimilation

Abstract. This study incorporates aerosol effects into satellite radiance calculations within the Global Data Assimilation System (GDAS) to investigate its impact on analyses and forecasts of African easterly waves (AEWs). Analysis fields from aerosol-aware assimilation experiment were compared an aerosol-blind control during August 2017. The results showed that warmed Saharan boundary layer, accelerated jet, modified time-averaged AEWs by enhancing northern track reducing southern track. changes tracks are qualitatively consistent with arguments baroclinic barotropic instability. During time period, we also examined two developed hurricanes Gert Harvey over Atlantic but structurally different Africa; AEW for consisted a vortex, while vortex. differences cases stronger vorticity Harvey, which attribute capturing radiative large-scale dust plume interacting vortex wave. Subsequent using Forecast (GFS, v14) reduced errors in downstream structure Harvey; neutral improvement was found Gert. Thus, aerosol-affected radiances system have ability account analyzed AEWs, which, turn, can improve forecasting downstream.