Comment on “Measurement of Aerosol Absorption Coefficient from Teflon Filters using the Integrating Plate and Integrating Sphere Techniques” by D. Campbell, S. Copeland and T. Cahill

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Abstract
Campbell et al. (1995) present a study of the light transmitted by and reflected from Teflon filters, and claim that the Laser Integrating Plate Method (LIPM), a variant of the Integrating Plate Method (IPM; Lin et al., 1973), provides accurate determination of the light absorption coefficient of the particles deposited on the filters. Close examination of the paper reveals that it is an incomplete evaluation of a technique that is inappropriately compared to a questionable facsimile of an established method (IPM), and that the authors have not demonstrated that the LIPM technique provides accurate measurements of aerosol absorption coefficient. As a result of the lack of corrections for multiple scattering and absorption in the Teflon filters, data obtained with the LIPM (e.g., Malm et al., 1994) may significantly overestimate the true aerosol absorption coefficient.