Intercomparison and characterization of 23 Aethalometers under laboratory and ambient air conditions: procedures and unit-to-unit variabilities

Abstract. Aerosolized black carbon is monitored worldwide to quantify its impact on air quality and climate. Given importance, measurements of mass concentrations must be conducted with instruments operating in quality-checked ensured conditions generate data which are reliable comparable temporally geographically. In this study, we report the results from largest characterization intercomparison filter-based absorption photometers, Aethalometer model AE33, belonging several European monitoring networks. Under controlled laboratory conditions, a total 23 measured three well-characterized aerosol sources: synthetic soot, nigrosin particles, ambient urban background Leipzig, Germany. The objective was investigate individual performance their comparability; analyzed response different sources caused by use obsolete filter materials application maintenance activities. Differences instrument-to-instrument variabilities equivalent (eBC) reported at 880 nm were determined before activities (for soot measurements, average deviation least square regression ?2.0 % range ?16 7 %; for 0.4 ?15 17 %), after they carried out ?1.0 ?14 8 0.5 ?12 15 %). deviations most cases explained type material employed instruments, particle load filter, flow calibration. activity show that relatively small unit-to-unit variability AE33-based light absorbing possible well-maintained instruments. It crucial follow guidelines proper tape AE33 ensure high (BC) among international observational