The desert dust impact on the Boundary Layer in the Atlantic

The study investigates the dynamics of the Boundary Layer (BL) over the Atlantic Ocean, with a focus on the region surrounding Cabo Verde, using a combination of ground-based PollyXT lidar, satellite lidar data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), radiosondes, and European Centre for Medium-Range Weather Forecasts (ECMWF) model output. The comparison of CALIPSO lidar profiles with ECMWF reanalysis revealed strong correlations for BL top over open ocean regions but less agreement in dust-affected areas closer to the African continent. In these regions, satellite lidar indicated higher BL tops than those estimated by ECMWF, likely due to the existence of high of aerosol concentrations, which play a crucial role in shaping dynamics. Observations in Cabo Verde highlight distinctive Marine Atmospheric Boundary Layer (MABL) characteristics, such as limited diurnal evolution, but also show the potential for BL heights to reach up to 1 km, driven by factors like strong winds that increase mechanical turbulence. Additionally, this study illustrates the challenges in accurately determining the BL height using lidar and radiosondes, examining cases with strong inversions that prevent vertical mixing, but also weaker inversions that allow for the penetration of dust particles within BL. Integrating multiple observational sources and techniques is essential for validating remote sensing data and enhancing BL characterizations. The findings underscore the complex interactions between marine and dust-laden air masses over the Atlantic, which are essential for understanding the dynamic processes in aerosol-cloud interactions.