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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 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-1 from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2 g-1 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 emphasize the necessity of incorporating EC observations to constrain the uncertainty associated with eBC.
2024
2015
The Forum for Air Quality Modelling (FAIRMODE) is a European network to exchange experiences and competences on the use of air quality models in the context of the Ambient Air Quality Directives. Its purpose is to identify and promote the use of good practices for air quality modelling and to propose harmonized ways to assess the quality of model-based air quality applications by EU Member States. The recommendations in this document are part of FAIRMODE’s contribution to the on-going revision of the EU Ambient Air Quality Directives (Directives 2008/50/EC and 2004/107/EC, hereafter AAQDs) initiated by the European Commission and are an update of the previous recommendations to the Fitness check of those Directives (Thunis et al. 2019). This document builds on the existing recommendations from FAIRMODE provided in 2019 regarding modelling applications. The current document has been revised in view of the latest consensus on the maturity of modelling applications and their uses for air quality management purposes. It provides strategic and technical recommendations where there is significant level consensus within the FAIRMODE expert community. It identifies how and where these recommendations may be included in the context of the revision of the AAQDs. These recommendations would require additional work of Member States were they to be implemented and would have implications for the work of the FAIRMODE network concerning the development of relevant guidance documents to support the recommendations.
Publications Office of the European Union
2022
2011
2007
2007
2010
The Forum for Air Quality Modelling (FAIRMODE) is a European network to exchange experiences and competence on the use of air quality models in the context of the Ambient Air Quality Directives. Its purpose is to identify and promote the use of good practices for air quality modelling and to propose harmonized ways to assess the quality of model-based air quality applications by EU Member States. The recommendations in this document are part of FAIRMODE’s contribution to the on-going fitness check of the two EU Ambient Air Quality Directives (Directives 2008/50/EC and 2004/107/EC) initiated by the European Commission. This document provides technical recommendations where the scientific consensus within FAIRMODE indicates that robust conclusions can be drawn, and identifies follow up actions. These recommendations might potentially affect the work of Member States in case they may be requested to be implemented. They may also be relevant to the outcome and follow-up to the fitness check of the Air Quality Directives. Finally, they have implications for the work of the FAIRMODE network itself, and guide future technical discussions
Publications Office of the European Union
2019
2013
2024
2015
2016
2010
2003
2003
2007
2007
2025
Measurements of solar ultraviolet radiation (UVR) performed between January and June 2020 at 10 Arctic and subarctic locations are compared with historical observations. Differences between 2020 and prior years are also assessed with total ozone column and UVR data from satellites. Erythemal (sunburning) UVR is quantified with the UV Index (UVI) derived from these measurements. UVI data show unprecedently large anomalies, occurring mostly between early March and mid‐April 2020. For several days, UVIs observed in 2020 exceeded measurements of previous years by up to 140%. Historical means were surpassed by more than six standard deviations at several locations in the Arctic. In northern Canada, the average UVI for March was about 75% larger than usual. UVIs in April 2020 were elevated on average by about 25% at all sites. However, absolute anomalies remained below 3.0 UVI units because the enhancements occurred during times when the solar elevation was still low.
2020
Active sampling methodology for atmospheric monitoring of cyclic volatile methylsiloxanes (cVMS) was improved to reduce sampling artifacts. A new sorbent, ABN Express (ABN), was evaluated for storage stability and measurement accuracy. Storage stability of cVMS on ABN showed less than 1% degradation of the individual 13C-labelled octamethylcyclotetrasiloxane (13C4-D4), decamethylcyclopentasiloxane (13C5-D5) and dodecamethylcyclohexasiloxane (13C6-D6) after 14 days storage at room temperature and at −20 °C whereas significant degradation was observed on ENV+ sorbent at room temperature (37–62 %) and −20 °C (9–16 %). 13C4-D4 formed on ENV+ spiked with 13C5-D5, and both 13C4-D4 and 13C5-D5 formed on ENV+ spiked with 13C6-D6. However, this was not observed on the ABN sorbent. Performance of ABN was compared to ENV+ through an 8-month Arctic sampling campaign at the Zeppelin Observatory (Ny Ålesund, Svalbard). Good agreement between ABN and ENV+ was observed for D4 in the spring/summer months. However, D5 and D6 was found to be consistently higher on the ABN sorbent during this time period with D6 showing the greatest deviation. During the winter months, larger deviations were observed between ABN and ENV+ sorbents with a factor of 4 times higher atmospheric concentrations of both D5 and D6 found on ABN; indicating sorbent related degradation on ENV+. Our findings show that the ABN sorbent provides greater stability and accuracy for atmospheric monitoring of cVMS. Implications of these improvements towards atmospheric fate processes will be discussed.
2020
2018