Correction of the Calibration of the 3-wavelength Particle Soot Absorption Photometer (3 PSAP)

During the Reno Aerosol Optics Study (RAOS) in June 2002, the prototype of the 3-wavelength Particle Soot Absorption Photometer (3 PSAP) was calibrated and a correction scheme was subsequently published (Virkkula, A., Ahlquist, N. C., Covert, D. S., Arnott, W. P., Sheridan, P. J., Quinn, P. K., and Coffman, D. J. (2005). Modification, Calibration and a Field Test of an Instrument for Measuring Light Absorption by Particles. Aerosol. Sci. Technol., 39:68-83). Unfortunately, the 3 PSAP flow rate had not been corrected during that analysis. The factors in the transmittance correction change after reanalysis with flow-corrected data. Reanalysis of the data also resolves an apparent discrepancy between the 1 PSAP and the 3 PSAP, and the two instruments now agree well.