Observational evidence for the vertical redistribution and scavenging of Saharan dust by tropical cyclones

Abstract

AbstractThe influence of the passage of organized tropical convection on the Saharan dust layer is quantified through a novel coupling of aerosol vertical structure from the polar orbiting Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations satellite to high temporal resolution storm tracks from the geostationary Pathfinder Atmospheres Extended cloud product. Three case studies corresponding to tropical storms Debby, Melissa, and Josephine in 2006, 2007, and 2008, respectively, present direct evidence that organized tropical convection consistently redistributes dust vertically in the atmosphere while simultaneously removing a significant fraction via wet scavenging. The evolution of the Saharan dust layer with passage of each storm suggests that convection deposits (1.6% ± 0.7%) of the dust mass in a layer between 8 km and 12 km and reduces downstream dust aerosol optical depths by an average of 80% ± 14% relative to before the storm overpass, far more than could be explained by dry deposition alone.