Particle Size Distributions Observed During the AEROSE V Campaign

Aerosol number distributions were measured over a three-week period (July 16 - August 4, 2009) during the Aerosol and Ocean Science Expeditions (AEROSE) V campaign in the tropical Atlantic Ocean. AEROSE are a series of trans-Atlantic intensive atmospheric field campaigns conducted aboard the NOAA Ship Ronald H. Brown (RHB) (Morris et al. 2006). AEROSE campaigns have sought to obtain a suite of complementary measurements to study the transport of aerosols from the African continent across the Atlantic Ocean, including microphysical evolution and regional impacts as well as Regional atmospheric chemistry and marine meteorology (Nalli et al. 2007). During the course of the campaign, several instruments were utilized to sample and measure aerosol microphysical properties. The Laser Particle Counters (LPCs) will be discussed here. The LPCs provided particle size distribution of aerosols across nine different size fractions. Two LPCs acquired data for this project. The sampling cycle was semi-continuous, with fifteen-minute intervals and sampling for one minute of one cubic foot of air. The preliminary analysis of the findings suggest that the expedition encountered at least two major distinctive air masses, one smoke and the other dust, plus a mixture. Also, the ITCZ was encountered twice, and the particle size distribution of the aerosols exhibited similar behavior on both occasions. Overall, three distinctive air masses were encountered by the AEROSE campaign, and this was confirmed by data analysis as well as satellite data analysis of MODIS, GOME, MOPITT, and METOSAT-9 imagery and products in combination with forecasts from the NAAPS, NOGAPS, and WRF models.