Improving Prediction and Advancing Understanding of Weather Systems over the Eastern Tropical Atlantic Using CPEX-CV Observations

Weather systems over North Africa and the tropical North Atlantic Ocean are strongly modulated by the warm and dry Saharan air layer, Saharan dust, and complex large-scale circulations, such as the African easterly jet (AEJ) and African easterly waves (AEWs). One of the objectives of NASA’s CPEX-CV field campaign, which took place in September 2022, was to collect data that could improve weather forecasts and advance understanding of the physics that controls weather systems over the tropical North Atlantic Ocean. This study evaluates the improvement of assimilating observations from the CPEX-CV field campaign on Tropical Storm Hermine (2022) forecasts using the Weather Research and Forecasting (WRF) dust model and the Gridpoint Statistical Interpolation (GSI) analysis system. The assimilated data include winds from the Doppler Aerosol WiNd lidar (DAWN), moisture from the High Altitude Lidar Observatory (HALO), dropsondes, and radiosondes. The assimilation of these observations greatly improves Hermine’s track and intensity forecast. To quantitatively assess to what extent these observations improve the forecast, we will diagnose the thermodynamic and dynamic structure of the storms; the structure and strength of the AEJ and AEWs; the tracks and energetics of AEWs; and cloud processes. Furthermore, the contribution of observations from individual instruments to the forecast improvements will be assessed and presented.