Journal Article
Atmospheric Measurement Techniques, vol. 14, iss. 11, pp. 7329-7340, 2021
Authors
Fan Mei, Steven Spielman, Susanne Hering, Jian Wang, Mikhail S. Pekour, Gregory Lewis, Beat Schmid, Jason Tomlinson, Maynard Havlicek
Abstract
Abstract. Capturing the vertical profiles and horizontal variations of atmospheric
aerosols often requires accurate airborne measurements. With the advantage
of avoiding health and safety concerns related to the use of butanol or
other chemicals, water-based condensation particle counters have emerged to
provide measurements under various environments. However, airborne
deployments are relatively rare due to the lack of instrument
characterization under reduced pressure at flight altitudes. This study
investigates the performance of a commercial “versatile” water-based condensation particle counter (vWCPC,
model 3789, TSI, Shoreview, MN, USA) under various ambient pressure
conditions (500–920 hPa) with a wide range of particle total number
concentrations (1500–70 000 cm−3). The effect of
conditioner temperature on vWCPC 3789 performance at low pressure is
examined through numerical simulation and laboratory experiments. We show
that the default instrument temperature setting of 30 ∘C for the
conditioner is not suitable for airborne measurement and that the optimal
conditioner temperature for low-pressure operation is 27∘. Under
the optimal conditioner temperature (27∘), the 7 nm cut-off size
is also maintained. Additionally, we show that insufficient droplet growth
becomes more significant under the low-pressure operation. The counting
efficiency of the vWCPC 3789 can vary up to 20 % for particles of
different chemical compositions (e.g., ammonium sulfate and sucrose
particles). However, such variation is independent of pressure.
