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).
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.