The Composition of Droplet-Forming Aerosol as a Function of Supersaturation
Abstract
Ambient aerosol measurements were conducted during February 2013 as part of the Department of Energy's Two Column Aerosol Project (TCAP). Located in North Truro, MA, the site provided access to a variety of air mass sources, including marine, continental, and aged urban outflow. A CCN closure study was conducted with measurements from a commercial Cloud Condensation Nuclei Counter (CCNC, Droplet Measurement Technologies) at a range of supersaturation conditions, as well as an Aerosol Mass Spectrometer (AMS, Aerodyne). Further measurements were conducted utilizing a Pumped Counterflow Virtual Impactor (PCVI) in order to separate the activated droplets, as a function of supersaturation, from un-activated aerosol at the output of the CCNC. Subsequent composition measurements of the droplet residuals were conducted with the AMS. High-resolution residual aerosol composition will be presented as a function of instrument supersaturation and air mass, and will be compared to the total ambient aerosol composition. Results indicate an enhancement of nitrate as well as compositional differences between the organic content of the un-activated aerosol and the droplet residuals. The advantages and disadvantages of the CCNC/PCVI/AMS instrumental setup will be discussed with a focus on how this new technique allows for an improvement in our understanding of warm cloud formation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A11D0079F
- Keywords:
-
- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE Aerosols and particles;
- 0320 ATMOSPHERIC COMPOSITION AND STRUCTURE Cloud physics and chemistry;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE Instruments and techniques