1Leibniz Institute for Tropospheric Research, Leipzig, Germany
2Finnish Meteorological Institute, Air Quality Research, Helsinki, Finland
3University of Helsinki, Department of Physics, Helsinki, Finland
4Institute for Climate and Global Change Research, School of Atmospheric Sciences Nanjing, University Nanjing, Nanjing, China
5NOAA, Earth System Research Laboratory, Boulder, CO 80305, USA
Received: 18 Oct 2013 – Discussion started: 18 Dec 2013
Abstract. We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from the literature and from dedicated experiments for the present manuscript. Uncertainties in the model and calibration experiments are discussed and uncertainties for retrieval of absorption coefficients are derived. For single-scattering albedos lower than 0.8, the new CTS method and also other correction schemes suffer from the uncertainty in calibration experiments, with an uncertainty of about 20% in the absorption coefficient. For high single-scattering albedos, the CTS correction significantly reduces errors. At a single-scattering albedo of about 0.98 the error can be reduced to 30%, whereas errors using the Bond correction (Bond et al., 1999) are up to 100%. The correction scheme was tested using data from an independent experiment. The tests confirm the modeled performance of the correction scheme when comparing the CTS method to other established correction methods.
Revised: 08 May 2014 – Accepted: 24 Jul 2014 – Published: 02 Dec 2014
Müller, T., Virkkula, A., and Ogren, J. A.: Constrained two-stream algorithm for calculating aerosol light absorption coefficient from the Particle Soot Absorption Photometer, Atmos. Meas. Tech., 7, 4049-4070, doi:10.5194/amt-7-4049-2014, 2014.