1. Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observationsMarjan Savadkoohi, Marco Pandolfi, Olivier Favez, Jean-Philippe Putaud, Konstantinos Eleftheriadis, Markus Fiebig, Philip Hopke, Paolo Laj, A. Wiedensohler, Griša Močnik, 2024, original scientific article Abstract: A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial–temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling regression MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2/g from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2/g from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasizes the necessity of incorporating EC observations to constrain the uncertainty associated with eBC. Keywords: equivalent black carbon, mass absorption cross-section, filter absorption photometers, elemental carbon, absorption, site specific MAC, rolling MAC Published in RUNG: 04.03.2024; Views: 1161; Downloads: 9 Full text (2,46 MB) This document has many files! More... |
2. Substantial brown carbon emissions from wintertime residential wood burning over FranceYunjiang Zhang, Alexandre Albinet, Jean-Eudes Petit, Véronique Jacob, Florie Chevrier, Gregory Gille, Sabrina Pontet, Eve Chrétien, Marta Dominik-Sègue, Gilles Levigoureux, Griša Močnik, Valérie Gros, Jean-Luc Jaffrezo, Olivier Favez, 2020, original scientific article Abstract: Brown carbon (BrC) is known to absorb light at subvisible wavelengths but its optical properties and sources are still poorly documented, leading to large uncertainties in climate studies. Here, we show its major wintertime contribution to total aerosol absorption at 370 nm (18–42%) at 9 different French sites. Moreover, an excellent correlation with levoglucosan (r2 = 0.9 and slope = 22.2 at 370 nm), suggesting important contribution of wood burning emissions to ambient BrC aerosols in France. At all sites, BrC peaks were mainly observed during late evening, linking to local intense residential wood burning during this time period. Furthermore, the geographic origin analysis also highlighted the high potential contribution of local and/or small-regional emissions to BrC. Focusing on the Paris region, twice higher BrC mass absorption efficiency value was obtained for less oxidized biomass burning organic aerosols (BBOA) compared to more oxidized BBOA (e.g., about 4.9 ± 0.2 vs. 2.0 ± 0.1 m2 g−1, respectively, at 370 nm). Finally, the BBOA direct radiative effect was found to be 40% higher when these two BBOA fractions are treated as light-absorbing species, compared to the non-absorbing BBOA scenario. Keywords: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France Published in RUNG: 20.07.2020; Views: 3780; Downloads: 0 This document has many files! More... |
3. The filter loading effect by ambient aerosols in filter absorption photometers depends on the mixing state of the sampled particlesLuka Drinovec, Asta Gregorič, Peter Zotter, Robert Wolf, Emily Anne Bruns, Andre S.H. Prevot, Jean-Eudes Petit, Olivier Favez, JEAN SCIARE, Ian J. Arnold, Rajan K. Chakrabarty, Hans Moosmüller, Agnes Fülöp-Miller, Griša Močnik, 2016, original scientific article Keywords: black carbon, mixing state, Aethalometer, filter-loading effect Published in RUNG: 02.11.2016; Views: 6193; Downloads: 284 Full text (2,07 MB) |