Continuous light absorption photometer (CLAP) performance

Poster PDF


Aerosol Properties


John A. Ogren — NOAA - Earth System Research Laboratory Jim Wendell — NOAA - ESRL, Global Monitoring Division
Patrick Sheridan — U.S. Department of Commerce/NOAA Derek Hageman — NOAA- Earth System Research Laboratory
Anne Jefferson — NOAA- Earth System Research Laboratory


The continuous light absorption photometer (CLAP) photometer is a multifilter absorption photometer developed at NOAA’s Earth System Research Laboratory. The instrument measures the aerosol absorption coefficient at three visible wavelengths: 470, 528, and 660 nm. The instrument has eight sample spots and two reference spots per filter and is heated to 38°C. To date 25 CLAP instruments have been deployed and are in operation as part of the NOAA cooperative instrument network. The ARM Facility has three of these instruments in operation as part of the Southern Great Plains (SGP), ARM Mobile Facility (AMF) and North Slope of Alaska (NSA) aerosol observing systems (AOS). Results showing data precision, comparison with the particle soot absorption photometer (PSAP) at multiple sites, and preliminary results from a laboratory comparison between the several CLAPs, PSAPs, Thermoscientific multiangle absorption photometer (MAAP), Aerodyne cavity-attenuated phase shift (CAPS) monitor and TSI nephelometer will be shown. A comparison of the Bond et al. PSAP correction scheme will be compared to a new two-stream radiative transfer model for transmission through a filter media will also be presented.