1. A European aerosol phenomenology - 9 : light absorption properties of carbonaceous aerosol particles across surface EuropeJordi Rovira, Marjan Savadkoohi, Gang I. Chen, Griša Močnik, Wenche Aas, Lucas Alados-Arboledas, B. Artíñano, Asta Gregorič, Matic Ivančič, Jesús Yus-Díez, 2024, original scientific article Abstract: Carbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (bAbs,BC) and BrC (bAbs,BrC) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)). Absorption coefficients showed a clear relationship with station setting decreasing as follows: TR > UB > SUB > RB > M, with exceptions. The contribution of bAbs,BrC to total absorption (bAbs), i.e. %AbsBrC, was lower at traffic sites (11–20 %), exceeding 30 % at some SUB and RB sites. Low AAE values were observed at TR sites, due to the dominance of internal combustion emissions, and at some remote RB/M sites, likely due to the lack of proximity to BrC sources, insufficient secondary processes generating BrC or the effect of photobleaching during transport. Higher bAbs and AAE were observed in Central/Eastern Europe compared to Western/Northern Europe, due to higher coal and biomass burning emissions in the east. Seasonal analysis showed increased bAbs, bAbs,BC, bAbs,BrC in winter, with stronger %AbsBrC, leading to higher AAE. Diel cycles of bAbs,BC peaked during morning and evening rush hours, whereas bAbs,BrC, %AbsBrC, AAE, and AAEBrC peaked at night when emissions from household activities accumulated. Decade-long trends analyses demonstrated a decrease in bAbs, due to reduction of BC emissions, while bAbs,BrC and AAE increased, suggesting a shift in CA composition, with a relative increase in BrC over BC. This study provides a unique dataset to assess the BrC effects on climate and confirms that BrC can contribute significantly to UV–VIS radiation presenting highly variable absorption properties in Europe.
Keywords: aerosol absorption, black carbon, brown carbon, climate change, air pollution
Published in RUNG: 10.12.2024; Views: 327; Downloads: 4
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2. Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosolsVaios Moschos, Katja Dzepina, Deepika Bhattu, Houssni Lamkaddam, Roberto Casotto, Kaspar R. Daellenbach, Francesco Canonaco, Pragati Rai, Wenche Aas, Silvia Becagli, Giulia Calzolai, Konstantinos Eleftheriadis, Claire E. Moffett, Jürgen Schnelle-Kreis, Mirko Severi, Sangeeta Sharma, Henrik Skov, Mika Vestenius, Wendy Zhang, Hannele Hakola, Heidi Hellén, Lin Huang, Jean-Luc Jaffrezo, Andreas Massling, Jakob K. Nøjgaard, Tuuka Petäjä, Olga Popovicheva, Rebecca J. Sheesley, Rita Traversi, Karl Espen Yttri, Julia Schmale, André S. H. Prévôt, Urs Baltensperger, Imad El Haddad, 2022, original scientific article Abstract: Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region.
Keywords: Arctic, Organic aerosols, Emission sources, Climate change
Published in RUNG: 01.03.2022; Views: 2639; Downloads: 0
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