Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

Autor: Jorge Saturno, Christopher Pöhlker, Dario Massabò, Joel Brito, Samara Carbone, Yafang Cheng, Xuguang Chi, Florian Ditas, Isabella Hrabě de Angelis, Daniel Morán-Zuloaga, Mira L. Pöhlker, Luciana V. Rizzo, David Walter, Qiaoqiao Wang, Paulo Artaxo, Paolo Prati, Meinrat O. Andreae
Přispěvatelé: University of Genoa (UNIGE), Laboratoire de Météorologie Physique (LaMP), Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Genova = University of Genoa (UniGe), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Atmospheric Measurement Techniques
Atmospheric Measurement Techniques, European Geosciences Union, 2017, 10 (8), pp.2837-2850. ⟨10.5194/amt-10-2837-2017⟩
Atmospheric Measurement Techniques, 2017, 10 (8), pp.2837-2850. ⟨10.5194/amt-10-2837-2017⟩
ISSN: 1867-1381
1867-8548
Popis: Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June–September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 ± 2.1 Mm−1, with a maximum of 15.9 Mm−1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.
Databáze: OpenAIRE
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