TY - JOUR
T1 - Addressing the advantages and limitations of using Aethalometer data to determine the optimal absorption Ångström exponents (AAEs) values for eBC source apportionment
AU - Savadkoohi, Marjan
AU - Gherras, Mohamed
AU - Favez, Olivier
AU - Petit, Jean Eudes
AU - Rovira, Jordi
AU - Chen, Gang I.
AU - Via, Marta
AU - Platt, Stephen
AU - Aurela, Minna
AU - Chazeau, Benjamin
AU - de Brito, Joel F.
AU - Riffault, Véronique
AU - Eleftheriadis, Kostas
AU - Flentje, Harald
AU - Gysel-Beer, Martin
AU - Hueglin, Christoph
AU - Rigler, Martin
AU - Gregorič, Asta
AU - Ivančič, Matic
AU - Keernik, Hannes
AU - Maasikmets, Marek
AU - Liakakou, Eleni
AU - Stavroulas, Iasonas
AU - Luoma, Krista
AU - Marchand, Nicolas
AU - Mihalopoulos, Nikos
AU - Petäjä, Tuukka
AU - Prevot, Andre S.H.
AU - Daellenbach, Kaspar R.
AU - Vodička, Petr
AU - Timonen, Hilkka
AU - Tobler, Anna
AU - Vasilescu, Jeni
AU - Dandocsi, Andrei
AU - Mbengue, Saliou
AU - Vratolis, Stergios
AU - Zografou, Olga
AU - Chauvigné, Aurélien
AU - Hopke, Philip K.
AU - Querol, Xavier
AU - Alastuey, Andrés
AU - Pandolfi, Marco
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2025/5/15
Y1 - 2025/5/15
N2 - The apportionment of equivalent black carbon (eBC) to combustion sources from liquid fuels (mainly fossil; eBCLF) and solid fuels (mainly non-fossil; eBCSF) is commonly performed using data from Aethalometer instruments (AE approach). This study evaluates the feasibility of using AE data to determine the absorption Ångström exponents (AAEs) for liquid fuels (AAELF) and solid fuels (AAESF), which are fundamental parameters in the AE approach. AAEs were derived from Aethalometer data as the fit in a logarithmic space of the six absorption coefficients (470–950 nm) versus the corresponding wavelengths. The findings indicate that AAELF can be robustly determined as the 1st percentile (PC1) of AAE values from fits with R2 > 0.99. This R2-filtering was necessary to remove extremely low and noisy-driven AAE values commonly observed under clean atmospheric conditions (i.e., low absorption coefficients). Conversely, AAESF can be obtained from the 99th percentile (PC99) of unfiltered AAE values. To optimize the signal from solid fuel sources, winter data should be used to calculate PC99, whereas summer data should be employed for calculating PC1 to maximize the signal from liquid fuel sources. The derived PC1 (AAELF) and PC99 (AAESF) values ranged from 0.79 to 1.08, and 1.45 to 1.84, respectively. The AAESF values were further compared with those constrained using the signal at mass-to-charge 60 (m/z 60), a tracer for fresh biomass combustion, measured using aerosol chemical speciation monitor (ACSM) and aerosol mass spectrometry (AMS) instruments deployed at 16 sites. Overall, the AAESF values obtained from the two methods showed strong agreement, with a coefficient of determination (R2) of 0.78. However, uncertainties in both approaches may vary due to site-specific sources, and in certain environments, such as traffic-dominated sites, neither approach may be fully applicable.
AB - The apportionment of equivalent black carbon (eBC) to combustion sources from liquid fuels (mainly fossil; eBCLF) and solid fuels (mainly non-fossil; eBCSF) is commonly performed using data from Aethalometer instruments (AE approach). This study evaluates the feasibility of using AE data to determine the absorption Ångström exponents (AAEs) for liquid fuels (AAELF) and solid fuels (AAESF), which are fundamental parameters in the AE approach. AAEs were derived from Aethalometer data as the fit in a logarithmic space of the six absorption coefficients (470–950 nm) versus the corresponding wavelengths. The findings indicate that AAELF can be robustly determined as the 1st percentile (PC1) of AAE values from fits with R2 > 0.99. This R2-filtering was necessary to remove extremely low and noisy-driven AAE values commonly observed under clean atmospheric conditions (i.e., low absorption coefficients). Conversely, AAESF can be obtained from the 99th percentile (PC99) of unfiltered AAE values. To optimize the signal from solid fuel sources, winter data should be used to calculate PC99, whereas summer data should be employed for calculating PC1 to maximize the signal from liquid fuel sources. The derived PC1 (AAELF) and PC99 (AAESF) values ranged from 0.79 to 1.08, and 1.45 to 1.84, respectively. The AAESF values were further compared with those constrained using the signal at mass-to-charge 60 (m/z 60), a tracer for fresh biomass combustion, measured using aerosol chemical speciation monitor (ACSM) and aerosol mass spectrometry (AMS) instruments deployed at 16 sites. Overall, the AAESF values obtained from the two methods showed strong agreement, with a coefficient of determination (R2) of 0.78. However, uncertainties in both approaches may vary due to site-specific sources, and in certain environments, such as traffic-dominated sites, neither approach may be fully applicable.
KW - Absorption Ångström exponent
KW - Aethalometer approach
KW - Equivalent black carbon
KW - Liquid fuels
KW - Solid fuels
KW - Source apportionment
UR - https://www.scopus.com/pages/publications/85218937038
U2 - 10.1016/j.atmosenv.2025.121121
DO - 10.1016/j.atmosenv.2025.121121
M3 - Article
AN - SCOPUS:85218937038
SN - 1352-2310
VL - 349
JO - Atmospheric Environment
JF - Atmospheric Environment
M1 - 121121
ER -