Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

cas-air > Cloud and Aerosol Spectrometer aboard aircraftInstrument Type(s) > Baseline • Guest

The Cloud, Aerosol, and Precipitation Spectrometer (CAPS) is a multipurpose, research-grade cloud spectrometer that includes three Droplet Measurement Technologies instruments plus temperature and relative humidity sensors. The Cloud and Aerosol Spectrometer (CAS) portion of the instrument uses forward and back scattering detection techniques to provide cloud droplet and aerosol sizes and optical properties. The Cloud Imaging Probe (CIP) uses shadow images from a photo-detector array to provide shape and size information for larger aerosol and hydrometeors. The HW sensor uses a platinum RTD wire sensor to detect liquid water content.


  • Fixed
  • AMF1
  • AMF2
  • AMF3


Yeom J, S Yum, R Shaw, I La, J Wang, C Lu, Y Liu, F Mei, B Schmid, and A Matthews. 2021. "Vertical variations of cloud microphysical relationships in marine stratocumulus clouds observed during the ACEā€ENA campaign." Journal of Geophysical Research: Atmospheres, 126(24), e2021JD034700, 10.1029/2021JD034700.


Chiu J, C Yang, P van Leeuwen, G Feingold, R Wood, Y Blanchard, F Mei, and J Wang. 2020. "Observational constraints on warm cloud microphysical processes using machine learning and optimization techniques." Geophysical Research Letters, 48(2), e2020GL091236, 10.1029/2020GL091236.
Research Highlight

Kleinman L, A Sedlacek III, K Adachi, P Buseck, S Collier, M Dubey, A Hodshire, E Lewis, T Onasch, J Pierce, J Shilling, S Springston, J Wang, Q Zhang, S Zhou, and R Yokelson. 2020. "Rapid evolution of aerosol particles and their optical properties downwind of wildfires in the western US." Atmospheric Chemistry and Physics, 20(21), 10.5194/acp-20-13319-2020.

Goldberger L. 2020. Cloud, Aerosol, and Precipitation Spectrometer Instrument Handbook. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-TR-246.

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