During the summer 2004, as part of the ICARTT field program, measurements were made to study chemical transport and transformation in cloud. This airborne study was held from July 20 to August 18, 2004 from the Canadian NRC Convair 580 aircraft. Observations were made primarily in convective clouds in the vicinity of Lake Erie with pollution sources including Windsor/Detroit, Cleveland, Chicago, and Sarnia. Instrumentation included gas-phase chemistry (O3, CO, SO2, NOx, HCHO, H2O2, HNO3, NH3), particle sulphate, nitrate and organic compounds with an Aerodyne aerosol mass spectrometer (AMS) and particle in liquid sampler (PILS), and physical characterization of aerosols and cloud.

Through the use of a Counterflow Virtual Impactor (CVI), cloud droplets were sampled, evaporated and the residual particles were then characterized both pyhsically with a TSI Differential Mobility Analyzer (DMA) and TSI condensation particle counter (CPC) and chemically with the aerosol mass spectrometer. Bulk cloudwater was also collected during flight with a slotted rod collector and analyzed for soluble inorganics, carbonyls, and hydrogen peroxide. In this paper, a preliminary investigation of the chemistry of the cloudwater residual paticles will be examined in comparison to the bulk cloudwater chemistry. Then gaseous, aerosol and cloudwater measurements of specific towering cumulus cases will be presented in further detail.