Cloud Condensation Nuclei Particle Counter Instrument Handbook - Airborne Version
The cloud condensation nuclei counter (CCN) is a U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility instrument for measuring the concentration of aerosol particles that can act as cloud condensation nuclei. Note: ARM deploys both ground and airborne versions of this instrument. This handbook covers only the airborne instrument; the ground version is covered by DOE/SC-ARM-TR-168. The main differences between the two are that the airborne CCN operates at fixed supersaturation and adapts thermal efficiency calculation in the data process. The CCN draws sample aerosol through a column with thermodynamically unstable supersaturated water vapor that can condense onto aerosol particles. Particles that are activated, i.e., grown larger in this process, are counted (and sized) by an optical particle counter (OPC). Thus, activated ambient aerosol particle number concentration as a function of supersaturation is measured. Models CCN-100 and CCN- 200 differ only in the number of humidifier columns and related subsystems: CCN-100 has one column and CCN-200 has two columns along with dual flow systems and electronics.