clap: Continuous Light Absorption Photometer

The Continuous Light Absorption Photometer (CLAP) operates on the same principle as the Particle Soot Absorption Photometer (PSAP), i.e., continuously measuring transmission through a filter substrate as sample air is drawn through it. The absorbing aerosol particles are collected in the filter.

The CLAP is part of the Aerosol Observing System (AOS).



  • Fixed
  • AMF1
  • AMF2
  • AMF3

Related Publications


Sherman JP, PJ Sheridan, JA Ogren, E Andrews, D Hageman, L Schmeisser, A Jefferson, and S Sharma. 2015. "A multi-year study of lower tropospheric aerosol variability and systematic relationships from four North American regions." Atmospheric Chemistry and Physics, 15(21), 10.5194/acp-15-12487-2015.


Jefferson A. 2014. Continuous Light Absorption Photometer (CLAP) Final Campaign Report. U.S. DOE, Office of Science, Office of Biological and Environmental Research. DOE/SC-ARM-14-013.


Ogren J, J Wendell, P Sheridan, D Hageman, and A Jefferson. 2013. Continuous Light Absorption Photometer (CLAP) Performance. Presented at 4th Atmospheric System Research (ASR) Science Team Meeting. Potomac, MD.

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