Cloud Forming Potential of Aminium Carboxylate Aerosols

Wednesday, 17 December 2014: 9:45 AM
Mario Estuardo Gomez Hernandez1,2, Megan McKeown2, Nathan Taylor2, Don R Collins2, Avi Lavi3, Yinon Rudich3 and Renyi Zhang1,2, (1)Texas A & M University, Department of Chemistry, College Station, TX, United States, (2)Texas A & M University, Department of Atmospheric Sciences, College Station, TX, United States, (3)Weizmann Institute of Science, Department of Earth and Planetary Science, Rehovot, Israel
Atmospheric aerosols affect visibility, air quality, human health, climate, and in particular the aerosol direct and indirect forcings represent the largest uncertainty in climate projections. In this paper, we present laboratory measurements of the hygroscopic growth factors (HGf) and cloud condensation nuclei (CCN) activity of a series of aminium carboxylate salt aerosols, utilizing a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) coupled to a Condensation Particle Counter (CPC) and a CCN counter. HGf measurements were conducted for size-selected aerosols with diameters ranging from 46 nm to 151 nm and at relative humidity (RH%) values ranging from 10 to 90%. In addition, we have calculated the CCN activation diameters for the aminium carboxylate aerosols and derived the hygroscopicity parameter (k or kappa) values for all species using three methods, i.e., the mixing rule approximation, HGf, and CCN results. Our results show that variations in the ratio of acid to base directly affect the activation diameter, HGf, and (k) values of the aminium carboxylate aerosols. Atmospheric implications of the variations in the chemical composition of aminium carboxylate aerosols on their cloud forming potential will be discussed.