Field Observations Using the Sulfuric Acid Dimethylamine-Reactive Condensation Particle Counter (SAD-RCPC)
Dominic Casalnuovo, Darren Cheng, Christine Troller, COTY JEN,
Carnegie Mellon University Abstract Number: 556
Working Group: Instrumentation and Methods
AbstractFreshly formed particles from sulfuric acid nucleation affect the Earth’s radiative balance by forming cloud condensation nuclei (CCN). Accurately predicting global sulfuric acid nucleation rates requires high temporal and spatial resolution measurements of gaseous sulfuric acid. Accomplishing this is challenging due to the difficulties in deploying a chemical ionization mass spectrometer (CIMS) in remote regions of the atmosphere. We have developed a complementary technique to measure sulfuric acid vapor concentrations (SAD-RCPC). The SAD-RCPC consists of a compact nucleation flow reactor that uses dimethylamine to convert atmospheric sulfuric acid vapor into measurable 1-nm particles in a controlled environment. The concentration of particles is measured using a 1-nm condensation particle counter and converted to sulfuric acid concentration using a semi-empirical acid-base nucleation model. The 1-nm particles are differentiated from prexisisitng particles using pulse height analysis of the CPC output. We present operational details, laboratory validation, and field measurements of sulfuric acid vapor using the SAD-RCPC. Laboratory results demonstrate the SAD-RCPC can measure sulfuric acid vapor concentrations of 10
6 to 10
9 cm
-3. Field measurements of sulfuric acid vapor from Pittsburgh, PA were taken alongside a nitrate CIMS. The resulting measurements taken by SAD-RCPC identified atmospheric concentrations of sulfuric acid vapor, opening the possibility of taking sulfuric acid measurements in locations previously not reachable by CIMS.