PARTPHASE

CLASIC - SGP Particle Phase Experiment

1 June 2007 - 22 June 2007

Lead Scientist: Scot Martin

Observatory: SGP

Chemical composition and phase change properties of particles in the sizerange of 40-400 nm were measured using an aerosol mass spectrometer (Aerodyne HR-TOF-AMS) and a 1x3TDMA. The phase transitions of ambient atmospheric particles were measured by application of a novel 1by3 tandem differential mobility analyzer (1x3 TDMA), an instrument based upon the principle of the irreversibility of the hygroscopic growth factor when a phase transition occurs. The hypotheses, measurements, and analyses focused on the objective of providing cause-and-effect relationships between RH history and particle chemical composition on the one hand and particle phase on the other hand. In addition to the 1×3 TDMA measurements, complimentary data at the SGP site was important in putting the observations into greater context and thereby understanding the cause-and-effect relationships between RH history and particle chemical composition and particle phase. Deployment of an aerosol mass spectrometer (Aerodyne HR-TOF-AMS) to the field site during the time of the intensive measurements along with the 1×3 TDMA provided aerosol chemistry data every few minutes (specifically, the organic-to-sulfate mass ratio and the nitrate-to-sulfate mass ratio).