Measuring aerosol black carbon age with aethalometers
Abstract
Aerosol mixing state is a parameter influencing optical properties of absorbing particles that is hard to measure. It was proposed that the lensing effect where transparent shell covers the absorbing particle can significantly enhance optical absorption (Bond et al., 2006). Aerosol mixing state can be assessed using advanced mass spectrometers ATOFMS (Healy et al., 2012), and with SP2 for particles with diameters above about 100 nm (Subramanian et al., 2010). Filter-based measurements of aerosol optical absorption are widely used to determine Black Carbon (BC) concentrations in real time. Measurements at multiple wavelengths permit the separation of contributions of BC from different combustion sources (Sandradewi 2008). However, filter-based methods are influenced by the non-linear response due to the »loading« effect, caused by the increasing sample deposit on the filter (Gundel 1984, Weingartner 2003, Arnott 2005, Virkkula 2007).The filterloading effect is the reduction of the filter based photometer sensitivity due to filter loading. It was shown that filter-loading effect differs between locations and seasons with indication that the filter loading effect in Aethalometer relates to the particle coating (Virkkula et al., 2007; Drinovec et al., 2015). Using Aethalometer model AE33 (Magee Scientific) it is possible to measure filter loading parameter k with high time resolution (Drinovec et al., 2015).Influence of coating on the parameter k was investigated both during the ambient and laboratory campaigns.
Domains
Environmental Sciences
Origin : Files produced by the author(s)
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