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Analysis of CCN Number, Hygroscopicity, and Droplet Activation in the Western Pacific Measured during CAMP2Ex
MICHAEL BATTAGLIA JR., Athanasios Nenes, Rodney J. Weber, Georgia Institute of Technology
Abstract Number: 377
Working Group: Aerosols, Clouds and Climate
Abstract
As part of the NASA CAMP2Ex field campaign, we observed cloud condensation nuclei (CCN) spectra between 0.1 and 0.6% supersaturation onboard the NASA P-3B research aircraft during seven research flights over the Pacific Ocean originating from Clark Freeport in the Philippines. The CCN spectra were measured with a Droplet Measurement Technologies CCN-100 continuous-flow streamwise thermal gradient chamber (CFSTGC) operating at Scanning Flow CCN Analysis mode (SFCA) at 500 mbar pressure. Combination of the CCN spectra and submicron aerosol size distributions from the fast integrated mobility spectrometer (FIMS) are used to obtain size-resolved CCN hygroscopicity - which are also compared against bulk hygroscopicity calculated with aerosol mass spectrometer (AMS) data. During periods of high sulfate fraction, the data is used as an in-flight calibration.
The hygroscopicity and aerosol observations, together with the observed distributions of updraft velocity are used as inputs to a cloud droplet parameterization to investigate the levels of cloud supersaturation values that would develop in clouds. From these simulations we also determine the degree to which clouds respond to aerosol perturbations, and quantitatively determine the contribution of aerosol and vertical velocity variability to the droplet number variability. Finally, we related our results to a growing body of studies focused on the drivers of droplet variability in the eastern Mediterranean, South Atlantic Ocean and southeastern United States.