Passive Cavity Aerosol Spectrometer Probe

Short Name or Variable Name

PCASP is a wing-mounted aerosol probe that uses a standard PMS canister.  Sample air enters the forward-facing inlet and decelerates by ~10x. Side-facing skarf tube provides suction for continuous flushing of the air to provide fast time response.

During cloud penetrations, the splash-breakup of cloud particles can produce large concentrations of spurious particles, and some of these can enter the PCASP air sample as a contamination. Internal diaphragm pump drives air flow through the optical cavity. Sample rate is ~1 cc/sec within a particle-free sheath flow of 15 cc/sec.

Alternate name: Passive Cavity Aerosol Spectrometer Probe with Signal Processing Package-200

Model: PCASP-100X

Measurements Provided: Size distribution and concentration of aerosol particles ~0.1 to 3.0 micrometer diameter in 30 size bins. *Note: due to its flow system design, the PCASP is not suitable for operation above about 8 km altitude.*

Typical Sampling Rates: 10 Hz

Example(s) of Measurement: Two examples of differential size distributions from the FRAPPE project:

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Calibration Methods

Size calibrations use monodisperse aerosols, including PSL (polystyrene latex) spheres or ammonium sulfate passed through DMA

Primary External Contacts
Bill Dawson, DMT; Jeff Snyder, U Wyo
Lead Contact
Mike Reeves
Typical Sampling Rates
10 Hz