AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Dual-Spot Aethalometer: Application of Real-Time Source Apportionment Algorithm for Black Carbon and Carbonaceous Aerosols
Luka Drinovec, Grisa Mocnik, Peter Zotter, Andre Prévôt, Christian Ruckstuhl, ANTHONY D.A. HANSEN, Aerosol d.o.o., Slovenia
Abstract Number: 516 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Filter-based measurements of aerosol optical absorption are widely used to determine Black Carbon (BC) concentrations in real time. Measurements at multiple wavelengths make the separation of contributions of BC from different combustion sources possible. These methods can suffer from non-linearity due to ‘loading’ effects of increasing aerosol deposit on the filter (Gundel 1984, Weingartner 2003, Arnott 2005, Virkkula 2007). Static algorithms to compensate for the effect, either by post-processing of the data or fixed in the instrument firmware, fail to capture the details and potential variability of these aerosol optical properties, and thus impact source apportionment using the data.
We have developed a new Aethalometer® AE33, in which two parallel sampling channels are operated at different loading rates. Combining the data from the two parallel analyses allows the measurement of BC with no loading effects, and yields a dynamical value of the non-linearity parameter. These analyses are performed for multiple optical wavelengths spanning the range from 370 nm to 950 nm and with a time resolution as rapid as 1 second. The results show greatly improved analytical performance for measurement of BC. The instrument is network-ready and is designed for both research and routine monitoring operations.
We present the use of this new instrument in urban and rural measurement campaigns in Switzerland, Austria and Slovenia showing absence of loading artefacts, and an application allowing on-line source apportionment similar to Sandradewi 2008.
Arnott, W. et al. (2005) Aerosol Sci. Technol. 39, 17-29.
Gundel, L.A., et al. (1984) Sci. Total Environment 36, 197-202.
Sandradewi, J. et al. (2008) Environ. Sci. Technol. 42, 3316–3323.
Virkkula, A. et al., (2007) J. Air & Waste Manage. Assoc. 57, 1214-1222.
Weingartner, E., et al. (2003) J. Aerosol Sci. 34, 1445-1463.
The work described herein was co-financed by the EUROSTARS grant E!4825 FC Aeth.