Evaluating the Variability of Saharan Dust Plume Origin and Composition from In Situ Samples

Saharan dust plumes have significant implications on cloud formation, radiative transfer, ecosystems, and human health. Studies have shown that cloud development can be altered by variations in the composition of aerosols. The focal point of this study is to investigate the variability of Saharan dust plume composition as a function of source region. The AEROSE(Saharan Dust Aerosols and Ocean Science Expedition) cruise provided a unique opportunity to collect and analyze in-situ data of numerous dust samples as it transected the Atlantic while intercepting African-borne dust air masses. Saharan dust samples collected aboard AEROSE cruises in 2007, 2009, and 2011 were analyzed for source region identification and elemental composition. Source regions of Saharan dust emissions were identified using a combination of MODIS(Moderate Resolution Imaging Spectroradiometer) satellite data analysis, HYSPLIT(Hybrid Single Particle Lagrangian Integrated Trajectory Model) analysis, NAAPS(Navy Aerosol Analysis and Prediction System) forecast data, and regional weather surface map data. Western Mauritania, Western Sahara, Northern Mali, Libya, and the Bodélé Depression were all identified as major dust emission source regions during the 2007, 2009, and 2011 AEROSE cruises. Elemental composition and evolution of the mineral dust particulate was determined using a combination of microanalytical techniques and corroboration with satellite and surface soil databases. It is anticipated that this characterization of Saharan dust emissions will enable future assessments on the impact of variations in dust composition on cloud microphysical behavior.