Tracer-based source-apportionment from the EUCAARI project and comparison with the EMEP model
Abstract
Particulate carbonaceous matter (PCM) is found to constitute 10-40% of PM10 levels at rural and natural background sites in Europe (Yttri et al., 2007; Putaud et al., 2004). Reviews have highlighted the complexity of the carbonaceous aerosol in terms of composition and formation mechanisms (e.g. Hallquist et al. 2009), but very few measurements have allowed an estimate of how much of PCM is from anthropogenic versus biogenic sources, or from primary emissions versus from secondary organic aerosol (SOA) formation. However, over the last few years a number measurement results using tracer methods have become available which have started to shed light on the important sources of PCM in Europe (Gelencsér et al., 2007; Saarikoski et al., 2008; Szidat et al., 2006, 2007, 2009). Within the EUCAARI project, data on 14C, EC, OC and GC-MS analyses are available from four sites, K-Puszta (Hungary), Hyytiälä (Finland), Melpitz (Germany), and San Pietro Capofiume (Italy). Additional data and analyses (AMS, NMR, other) are available from a number of other sites, including for example Barcelona (Spain), or Vavihill (Sweden). The link between tracers and their associated organic carbon amounts are of course very uncertain. Following Gelencsér et al. (2007) we define both a central best-estimate value for each factor and a plausible range of uncertainty. In order to tackle the multitude of possible combinations of these uncertain parameters, we have made use of an effective statistical approach known as Latin-hypercube sampling (LHS) (Iman et al., 1981). LHS approaches are somewhat similar to Monte Carlo calculations, and allow vast numbers of combinations of input variables to be computed. This talk focuses on the use of such tracers to shed light on the sources of PCM in Europe. We make use of methodologies similar to those used by Szidat et al. (2006, 2009), and within the EU CARBOSOL project (Gelencsér et al., 2007), in an effort to calculate the relative contributions of the primary/secondary and anthropogenic/natural sources of the carbonaceous aerosol. The results clearly show the importance of BSOA sources in summer and of biomass-burning in wintertime, but also provide information on the amounts of primary biological material and other smaller contributers. Model results for SOA are also extremely sensitive to a wide range of assumptions, with little bases for choosing between different approaches. We use the EMEP MSC-W model in different configurations to illustrate how source-apportionment analysis can be used to discriminate between different SOA schemes, and to constrain model possibilities.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A21I..03S
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE / Biosphere/atmosphere interactions