Molecular Composition of Cloud Water in the Eastern US and Impacts of Aqueous Reactions (Invited Presentation)

Clouds impact climate and air quality by interacting with atmospheric particles and trace gases. Recent studies have highlighted the potential for aqueous-phase reactions within cloud droplets to lead to the formation of high molecular weight organic compounds; however, few studies have investigated the molecular composition of cloud droplets. In this study, cloud water was collected in two locations in the eastern United States: over Alabama during the summer 2013 Southern Oxidant and Aerosol Study (SOAS) and at Whiteface Mountain, New York in the summers of 2013 and 2014. Electrospray ionization coupled with high resolution mass spectrometry was utilized to probe the organic molecular composition of the cloud water samples. In addition, nanospray desorption electrospray ionization (nano-DESI) high resolution mass spectrometry was used to examine that molecular composition of atmospheric particles collected during the SOAS aircraft sampling for a direct comparison of the particles and cloud water. The data provide insights into the processing of organic compounds in cloud droplets and improve our understanding of atmospheric organic particle budgets.