Articles | Volume 10, issue 12
Atmos. Meas. Tech., 10, 4805–4818, 2017
https://doi.org/10.5194/amt-10-4805-2017
Atmos. Meas. Tech., 10, 4805–4818, 2017
https://doi.org/10.5194/amt-10-4805-2017

Research article 11 Dec 2017

Research article | 11 Dec 2017

Continuous light absorption photometer for long-term studies

John A. Ogren1,2, Jim Wendell1, Elisabeth Andrews2, and Patrick J. Sheridan1 John A. Ogren et al.
  • 1Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, 80305, USA
  • 2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, 80303, USA

Abstract. A new photometer is described for continuous determination of the aerosol light absorption coefficient, optimized for long-term studies of the climate-forcing properties of aerosols. Measurements of the light attenuation coefficient are made at blue, green, and red wavelengths, with a detection limit of 0.02 Mm−1 and a precision of 4 % for hourly averages. The uncertainty of the light absorption coefficient is primarily determined by the uncertainty of the correction scheme commonly used to convert the measured light attenuation to light absorption coefficient and ranges from about 20 % at sites with high loadings of strongly absorbing aerosols up to 100 % or more at sites with low loadings of weakly absorbing aerosols. Much lower uncertainties (ca. 40 %) for the latter case can be achieved with an advanced correction scheme.

Download
Short summary
A new photometer for continuous measurements of aerosol light absorption coefficient is described, optimized for long-term studies of the climate-forcing properties of aerosols. The device is small, sensitive, precise, and simple to operate. It is suitable for long-term measurements at remote locations and is currently in operation at about two dozen sites worldwide.