Trans-Atlantic transport of Saharan dust aerosols: aerosol mass densities obtained during AEROSE-V

The Saharan Desert is the source of nearly four billion metric tons of mineral aerosols entering the atmosphere annually. These dust aerosols, along with biomass aerosols originating from natural and human-induced processes in west and central Africa, and aerosols originating from urban and industrial activities, are carried by the Northeast Trade Winds across the Atlantic Ocean in to the Caribbean and eastern seaboard of the US. The impacts of these aerosols on our atmosphere, ocean and health are manifest in regional impacts on climate and weather, deposition of harmful species in the ocean mixed layer, and through exposures to fungi, bacteria and air toxics that may induce and exacerbate asthma and other respiratory ailments. The trans-Atlantic Aerosol and Ocean Science Expeditions (AEROSE) were conducted in 2004 and annually since 2006 to better understand the dispersion and the impacts of these aerosols of African origin. AEROSE-V took place during July 11 – August 6, 2009. Ambient aerosol mass densities were measured using a Quartz Crystal Microbalance Cascade Impactor (QCM). Size-segregated samples were also collected in order to study the compositional variability in the ambient mass distributions observed over the tropical Atlantic Ocean. In situ aerosol measurements were compared with outputs and analysis from NAAPS forecast models, satellite imagery, and other atmospheric data acquired aboard the ship. Preliminary analysis indicates that three distinctive air masses (biomass aerosol, Saharan dust, mixed zone) were encountered and distinguished by unique mass density distributions and evolution. The biomass aerosol appears to have originated from extensive wildfires burning in Central Africa. This research was supported by the Department of Commerce through the NOAA Educational Partnership Program, Cooperative Agreement NA17AE1625. The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official NOAA or U.S. Government position, policy, or decision.