caps-pmex: Cavity Attenuated Phase Shift Extinction Monitor

The cavity attenuated phase shift extinction monitor is an optical extinction spectrometer that measures aerosols, broadband scatterers and absorbers of light that interact with solar radiation and influence the Earth’s radiation balance. The CAPS PMex uses a visible-light-emitting diode (LED), a sampling cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector.



  • Fixed
  • AMF1
  • AMF2
  • AMF3

Active Instrument Locations

Facility Name Instrument Start Date
Lamont, OK (Extended and Co-located with C1) 2016-11-15


Forestieri S, T Helgestad, A Lambe, L Renbaum-Wolff, D Lack, P Massoli, E Cross, M Dubey, C Mazzoleni, J Olfert, A Sedlacek III, A Freedman, P Davidovits, T Onasch, and C Cappa. 2018. "Measurement and modeling of the multiwavelength optical properties of uncoated flame-generated soot." Atmospheric Chemistry and Physics, 18(16), 10.5194/acp-18-12141-2018.


Dubey M, A Aiken, LK Berg, A Freedman, and K Gorkowski. 2016. Two-Column Aerosol Project: Aerosol Light Extinction Measurements Field Campaign Report. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-16-047.

Collier S, S Zhou, T Onasch, D Jaffe, L Kleinman, A Sedlacek, N Briggs, J Hee, E Fortner, J Shilling, D Worsnop, R Yokelson, C Parworth, X Ge, J Xu, Z Butterfield, D Chand, M Dubey, M Pekour, S Springston, and Q Zhang. 2016. "Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign." Environmental Science & Technology, 50(16), 10.1021/acs.est.6b01617.
Research Highlight

Sedlacek AJ. 2016. Cavity Attenuated Phase Shift Monitor Instrument Handbook. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-TR-155.

Worsnop DR, LR Williams, SC Herndon, M Dubey, NL Ng, J Thornton, B Knighton, R Coulter, and A Prevot. 2016. Clean Air for London (CLEARFLO) Final Campaign Summary. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-15-015.

Kleinman LI, AJ Sedlacek, WP Arnott, PR Buseck, P Davidovits, JS Gaffney, ER Lewis, W Lin, H Moosmuller, TB Onasch, JE Shilling, J Wang, RJ Yokelson, and RA Zaveri. 2016. Biomass Burning Observation Project (BBOP) Final Campaign Report. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-15-083.


Petäjä T. 2013. Science Plan Biogenic Aerosols Effects on Clouds and Climate (BAECC). ARM user facility. DOE/SC-ARM-13-024.

Kleinman LI and AJ Sedlacek. 2013. Biomass Burning Observation Project (BBOP) Science Plan. DOE ARM Climate Research Facility. DOE/SC-ARM-13-014.


Wood R, CS Bretherton, CR Mecheso, RA Weller, B Huebert, F Straneo, BA Albrecht, H Coe, G Vaughan, P Daum, C Fairall, D Chand, L Gallardo Klenner, R Garreaud, C Grados, DS Covert, TS Bates, R Krejci, LM Russell, S de Szoeke, A Brewer, SE Yuter, SR Springston, A Chaigneau, T Toniazzo, P Minnis, R Palikonda, SJ Abel, WO Brown, S Williams, J Fochesatto, J Brioude, and KN Bower. 2011. "The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx): goals, platforms, and field operations." Atmospheric Chemistry and Physics, 11(2), 10.5194/acp-11-627-2011.


Zaveri RA, WJ Shaw, and DJ Cziczo. 2010. CARES: Carbonaceous Aerosol and Radiative Effects Study Operations Plan. DOE ARM Climate Research Facility. DOE/SC-ARM-10-018.

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