Cloud Droplet Probe (CDP)

This miniature, lightweight, low-power cloud particle spectrometer measures droplets in the range of 2-50 µm in concentrations as high as 2000 particles/cm³. This popular instrument mounts easily on aircraft, towers, unmanned airborne vehicles (UAV), and spray rigs, to name just a few of the many applications.

Specifications
Particle-by-Particle Feature
Selected Bibliography
Print Version of Brochure
Hardware Manual without schematics (2.9 MB)
Manual for the CDP's Particle-Analysis Software
Technical Note on the CDP Dynamic Threshold feature

Specifications

Measures cloud particles in the range of 2 - 50 µm

Particle-sizing and concentration histograms of 20, 30, or 40-bin resolution

Light source: 660 nm, 50 mW diode laser

Sample area: .24 mm²

Collects forward-scattered light over angles of 4 - 12 degrees

Concentration range: 0 - 5,000 particles/cm³

Airspeed range: 10 - 200 m/sec, altitude limit 50,000 ft

Signal-processing module outputs data through a standard RS-422 or RS-232 interface to DMT's PADS or other software

Software-selectable adjustable bin thresholds

Monitors 8 analog "housekeeping" parameters

Optional particle-by-particle feature provides precise sizing information and data on particle interarrival times

Dimensions: Strut is 8.5" L x 4.675" H x 5.875" H; signal-processing module is 7" L x 3.25" W x 2" H, remotely mounted. The compact design reflects cutting-edge airborne particle instrumentation.

Weight: 2.5 lbs. for sensor strut, 1.5 lbs. for electronics module

Power: less than 30 W at 28 VDC, plus 200 W for anti-ice heaters

System includes spectrometer, test cables, shipping case, one day of training at DMT's facility, and one-year warranty

Particle-by-Particle Feature

Standard CDPs provide particle-size information in histogram form. This system allows users to easily identify size distributions of particles within the range that the instrument measures. Standard CDPs do not provide precise size data for individual particles, however—particles are simply grouped with other particles of a similar diameter.

For more precise information on individual particle sizes, the CDP can be ordered with a particle-by-particle feature (CDP-PBP). CDP-PBPs provide all the functionality of a standard CDP along with much more detailed information about the first 256 particles detected during every sample. For particles observed during the particle-by-particle anaylsis, the CDP-PBP reports the following data:

Particle size in counts. This is the peak digital signal detected by the instrument‘s optics and is proportional to the particle‘s optical-scattering cross-section. This value can be used to determine particle size.
Individual particle time with µsec resolution.
Inter-arrival particle time (IPT). This is the time in msec that has elapsed between qualified particles.

Selected Bibliography

S. Lance, C. A. Brock, D. Rogers, and J. A. Gordon, “Water droplet calibration of the Cloud Droplet Probe (CDP) and in-flight performance in liquid, ice and mixed-phase clouds during ARCPAC,” Atmos. Meas. Tech., 3, 1683–1706, 2010. doi:10.5194/amt-3-1683-2010. link

M. W. Gallagher, P. J. Connolly, A. Heymsfield et al. "Observations and modelling of microphysical variability, aggregation and sedimentation in tropical storm cirrus outflow regions." Atmos. Chem. Phys. Discuss.,11, 23761–23800, 2011. doi:10.5194/acpd-11-23761-2011. link

J. Crosier, K.N. Bower, et al, “Observations of ice multiplication in a weakly convective cell embedded in supercooled mid-level stratus,” Atmos. Chem. Phys. Discuss., 10, 19381–19427, 2010. doi:10.5194/acpd-10-19381-2010. link

D. Rosenfeld, W. L. Woodley, D. Axisa, E. Freud, J. G. Hudson, and A. Givati (2008), "Aircraft measurements of the impacts of pollution aerosols on clouds and precipitation over the Sierra Nevada," J. Geophys. Res. , 113, D15203, doi:10.1029/2007JD009544. link