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Rolling vs. seasonal PMF : real-world multi-site and synthetic dataset comparison
Marta Via, Gang Chen, Francesco Canonaco, Kaspar Rudolf Daellenbach, Benjamin Chazeau, Hasna Chebaicheb, Jianhui Jiang, Hannes Keernik, Chunshui Lin, Nicolas Marchand, 2022, izvirni znanstveni članek

Opis: Abstract. Particulate matter (PM) has become a major concern in terms of human health and climate impact. In particular, the source apportionment (SA) of organic aerosols (OA) present in submicron particles (PM1) has gained relevance as an atmospheric research field due to the diversity and complexity of its primary sources and secondary formation processes. Moreover, relatively simple but robust instruments such as the Aerosol Chemical Speciation Monitor (ACSM) are now widely available for the near-real-time online determination of the composition of the non-refractory PM1. One of the most used tools for SA purposes is the source-receptor positive matrix factorisation (PMF) model. Even though the recently developed rolling PMF technique has already been used for OA SA on ACSM datasets, no study has assessed its added value compared to the more common seasonal PMF method using a practical approach yet. In this paper, both techniques were applied to a synthetic dataset and to nine European ACSM datasets in order to spot the main output discrepancies between methods. The main advantage of the synthetic dataset approach was that the methods' outputs could be compared to the expected “true” values, i.e. the original synthetic dataset values. This approach revealed similar apportionment results amongst methods, although the rolling PMF profile's adaptability feature proved to be advantageous, as it generated output profiles that moved nearer to the truth points. Nevertheless, these results highlighted the impact of the profile anchor on the solution, as the use of a different anchor with respect to the truth led to significantly different results in both methods. In the multi-site study, while differences were generally not significant when considering year-long periods, their importance grew towards shorter time spans, as in intra-month or intra-day cycles. As far as correlation with external measurements is concerned, rolling PMF performed better than seasonal PMF globally for the ambient datasets investigated here, especially in periods between seasons. The results of this multi-site comparison coincide with the synthetic dataset in terms of rolling–seasonal similarity and rolling PMF reporting moderate improvements. Altogether, the results of this study provide solid evidence of the robustness of both methods and of the overall efficiency of the recently proposed rolling PMF approach.
Ključne besede: particulate matter, synthetic dataset comparison, source apportionment, organic aerosols
Objavljeno v RUNG: 10.05.2024; Ogledov: 160; Prenosov: 4
.pdf Celotno besedilo (2,03 MB)
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Increase in secondary organic aerosol in an urban environment : Increase in secondary organic aerosol in an urban environment
Marta Via, Maria Cruz Minguillon, Cristina Reche, Xavier Querol, Andrés Alastuey, 2021, izvirni znanstveni članek

Opis: The evolution of fine aerosol (PM1) species as well as the contribution of potential sources to the total organic aerosol (OA) at an urban background site in Barcelona, in the western Mediterranean basin (WMB) was investigated. For this purpose, a quadrupole aerosol chemical speciation monitor (Q-ACSM) was deployed to acquire real-time measurements for two 1-year periods: May 2014–May 2015 (period A) and September 2017–October 2018 (period B). Total PM1 concentrations showed a slight decrease (from 10.1 to 9.6 μgm�3 from A to B), although the relative contribution of inorganic and organic compounds varied significantly. Regarding inorganic compounds, SO42- , black carbon(BC) and NH4+ showed a significant decrease from period A to B (21 %, 18% and 9 %, respectively), whilst NO3- concentrations were higher in B (8 %). Source apportionment revealed OA contained 46% and 70% secondary OA (SOA) in periods A and B, respectively. Two secondary oxygenated OA sources (OOA) were differentiated by their oxidation status (i.e. ageing): less oxidized (LO-OOA) and more oxidized (MO-OOA). Disregarding winter periods, when LO-OOA production was not favoured, LO-OOA transformation into MO-OOA was found to be more effective in period B. The lowest LO-OOA-to-MO-OOA ratio, excluding winter, was in September–October 2018 (0.65), implying an accumulation of aged OA after the high temperature and solar radiation conditions in the summer season. In addition to temperature, SOA (sum of OOA factors) was enhanced by exposure to NOx-polluted ambient and other pollutants, especially to O3 and during afternoon hours. The anthropogenic primary OA sources identified, cooking-related OA (COA), hydrocarbon-like OA (HOA), and biomass burning OA (BBOA), decreased from period A to B in both absolute concentrations and relative contribution (as a whole, 44% and 30 %, respectively). However, their concentrations and proportion to OA grew rapidly during highly polluted episodes. The influence of certain atmospheric episodes on OA sources was also assessed. Both SOA factors were boosted with long- and medium-range circulations, especially those coming from inland Europe and the Mediterranean (triggering mainly MO-OOA) and summer breeze-driven regional circulation (mainly LO-OOA). In contrast, POA was enhanced either during air-renewal episodes or stagnation anticyclonic events.
Ključne besede: aerosol, organic aerosol, source apportionment, PM1, particulate matter
Objavljeno v RUNG: 10.05.2024; Ogledov: 190; Prenosov: 3
.pdf Celotno besedilo (4,93 MB)
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