A Simple Procedure for Correcting Loading Effects of Aethalometer Data

• Published in: Journal of the Air & Waste Management Association (1995) Vol. 57; no. 10; pp. 1214 - 1222
• Main Authors: Virkkula, Aki, Mäkelä, Timo, Hillamo, Risto, Yli-Tuomi, Tarja, Hirsikko, Anne, Hämeri, Kaarle, Koponen, Ismo K.
• Format: Journal Article
• Language: English
• Published: Pittsburgh, PA Air & Waste Management Association 01.10.2007; Air and Waste Management Association; Taylor & Francis Ltd
• Subjects: Aerosols; Aerosols - analysis; Air pollution; Algorithms; Applied sciences; Atmospheric pollution; Atoms & subatomic particles; Black carbon; Control; Environmental aspects; Environmental Monitoring; Exact sciences and technology; Finland; Forest & brush fires; Fossil fuels; Light; Models, Chemical; Motor vehicles; Pollution; Pollution control devices; Public transportation; Seasons; Soot - analysis; Soot - chemistry; Summer; Wavelengths; Winter; Finland; Carbon black; Seasonal variation; Aerosols; Rural area; Air pollution; Road traffic; Motor vehicle; Urban area; Subways; Algorithm
• ISSN: 1096-2247; 2162-2906; 2162-2906
• DOI: 10.3155/1047-3289.57.10.1214

A simple method for correcting for the loading effects of aethalometer data is presented. The formula BC(CORRECTED) = (1 + k x ATN) x BC(NONCORRECTED), where ATN is the attenuation and BC is black carbon, was used for correcting aethalometer data obtained from measurements at three different sites: a subway station in Helsinki, an urban background measurement station in Helsinki, and a rural station in Hyytiälä in central Finland. The BC data were compared with simultaneously measured aerosol volume concentrations (V). After the correction algorithm, the BC-to-V ratio remained relatively stable between consequent filter spots, which can be regarded as indirect evidence that the correction algorithm works. The k value calculated from the outdoor sites had a clear seasonal cycle that could be explained by darker aerosol in winter than in summer. When the contribution of BC to the total aerosol volume was high, the k factor was high and vice versa. In winter, the k values at all wavelengths were very close to that obtained from the subway station data. In summer, the k value was wavelength dependent and often negative. When the k value is negative, the noncorrected BC concentrations overestimated the true concentrations.