Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning

<p>Measurement of light absorption of solar radiation by aerosols is vital for assessing direct aerosol radiative forcing, which affects local and global climate. Low-cost and easy-to-operate filter-based instruments, such as the Particle Soot Absorption Photometer (PSAP), that collect aerosol...

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Main Authors: J. Kumar, T. Paik, N. J. Shetty, P. Sheridan, A. C. Aiken, M. K. Dubey, R. K. Chakrabarty
Format: Article
Language:English
Published: Copernicus Publications 2022-08-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/15/4569/2022/amt-15-4569-2022.pdf
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author J. Kumar
T. Paik
N. J. Shetty
P. Sheridan
A. C. Aiken
M. K. Dubey
R. K. Chakrabarty
author_facet J. Kumar
T. Paik
N. J. Shetty
P. Sheridan
A. C. Aiken
M. K. Dubey
R. K. Chakrabarty
author_sort J. Kumar
collection DOAJ
description <p>Measurement of light absorption of solar radiation by aerosols is vital for assessing direct aerosol radiative forcing, which affects local and global climate. Low-cost and easy-to-operate filter-based instruments, such as the Particle Soot Absorption Photometer (PSAP), that collect aerosols on a filter and measure light attenuation through the filter are widely used to infer aerosol light absorption. However, filter-based absorption measurements are subject to artifacts that are difficult to quantify. These artifacts are associated with the presence of the filter medium and the complex interactions between the filter fibers and accumulated aerosols. Various correction algorithms have been introduced to correct for the filter-based absorption coefficient measurements toward predicting the particle-phase absorption coefficient (<span class="inline-formula"><i>B</i><sub>abs</sub></span>). However, the inability of these algorithms to incorporate into their formulations the complex matrix of influencing parameters such as particle asymmetry parameter, particle size, and particle penetration depth results in prediction of particle-phase absorption coefficients with relatively low accuracy. The analytical forms of corrections also suffer from a lack of universal applicability: different corrections are required for rural and urban sites across the world. In this study, we analyzed and compared 3 months of high-time-resolution ambient aerosol absorption data collected synchronously using a three-wavelength photoacoustic absorption spectrometer (PASS) and PSAP. Both instruments were operated on the same sampling inlet at the Department of Energy's Atmospheric Radiation Measurement program's Southern Great Plains (SGP) user facility in Oklahoma. We implemented the two most commonly used analytical correction algorithms, namely, Virkkula (2010) and the average of Virkkula (2010) and Ogren (2010)–Bond et al. (1999) as well as a random forest regression (RFR) machine learning algorithm to predict <span class="inline-formula"><i>B</i><sub>abs</sub></span> values from the PSAP's filter-based measurements. The predicted <span class="inline-formula"><i>B</i><sub>abs</sub></span> was compared against the reference <span class="inline-formula"><i>B</i><sub>abs</sub></span> measured by the PASS. The RFR algorithm performed the best by yielding the lowest root mean square error of prediction. The algorithm was trained using input datasets from the PSAP (transmission and uncorrected absorption coefficient), a co-located nephelometer (scattering coefficients), and the Aerosol Chemical Speciation Monitor (mass concentration of non-refractory aerosol particles). A revised form of the Virkkula (2010) algorithm suitable for the SGP site has been proposed; however, its performance yields approximately 2-fold errors when compared to the RFR algorithm. To generalize the accuracy and applicability of our proposed RFR algorithm, we trained and tested it on a dataset of laboratory measurements of combustion aerosols. Input variables to the algorithm included the aerosol number size distribution from the Scanning Mobility Particle Sizer, absorption coefficients from the filter-based Tricolor Absorption Photometer, and scattering coefficients from a multiwavelength nephelometer. The RFR algorithm predicted <span class="inline-formula"><i>B</i><sub>abs</sub></span> values within 5 % of the reference <span class="inline-formula"><i>B</i><sub>abs</sub></span> measured by the multiwavelength PASS during the laboratory experiments. Thus, we show that machine learning approaches offer a promising path to correct for biases in long-term filter-based absorption datasets and accurately quantify their variability and trends needed for robust radiative forcing determination.</p>
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spelling doaj.art-d5a2c3b80da54fd8bd7bddcd304252ab2022-12-22T02:35:25ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482022-08-01154569458310.5194/amt-15-4569-2022Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learningJ. Kumar0T. Paik1N. J. Shetty2P. Sheridan3A. C. Aiken4M. K. Dubey5R. K. Chakrabarty6Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USACenter for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USACenter for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USANOAA Global Monitoring Laboratory, Boulder, CO 80305, USAEarth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 USAEarth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 USACenter for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA<p>Measurement of light absorption of solar radiation by aerosols is vital for assessing direct aerosol radiative forcing, which affects local and global climate. Low-cost and easy-to-operate filter-based instruments, such as the Particle Soot Absorption Photometer (PSAP), that collect aerosols on a filter and measure light attenuation through the filter are widely used to infer aerosol light absorption. However, filter-based absorption measurements are subject to artifacts that are difficult to quantify. These artifacts are associated with the presence of the filter medium and the complex interactions between the filter fibers and accumulated aerosols. Various correction algorithms have been introduced to correct for the filter-based absorption coefficient measurements toward predicting the particle-phase absorption coefficient (<span class="inline-formula"><i>B</i><sub>abs</sub></span>). However, the inability of these algorithms to incorporate into their formulations the complex matrix of influencing parameters such as particle asymmetry parameter, particle size, and particle penetration depth results in prediction of particle-phase absorption coefficients with relatively low accuracy. The analytical forms of corrections also suffer from a lack of universal applicability: different corrections are required for rural and urban sites across the world. In this study, we analyzed and compared 3 months of high-time-resolution ambient aerosol absorption data collected synchronously using a three-wavelength photoacoustic absorption spectrometer (PASS) and PSAP. Both instruments were operated on the same sampling inlet at the Department of Energy's Atmospheric Radiation Measurement program's Southern Great Plains (SGP) user facility in Oklahoma. We implemented the two most commonly used analytical correction algorithms, namely, Virkkula (2010) and the average of Virkkula (2010) and Ogren (2010)–Bond et al. (1999) as well as a random forest regression (RFR) machine learning algorithm to predict <span class="inline-formula"><i>B</i><sub>abs</sub></span> values from the PSAP's filter-based measurements. The predicted <span class="inline-formula"><i>B</i><sub>abs</sub></span> was compared against the reference <span class="inline-formula"><i>B</i><sub>abs</sub></span> measured by the PASS. The RFR algorithm performed the best by yielding the lowest root mean square error of prediction. The algorithm was trained using input datasets from the PSAP (transmission and uncorrected absorption coefficient), a co-located nephelometer (scattering coefficients), and the Aerosol Chemical Speciation Monitor (mass concentration of non-refractory aerosol particles). A revised form of the Virkkula (2010) algorithm suitable for the SGP site has been proposed; however, its performance yields approximately 2-fold errors when compared to the RFR algorithm. To generalize the accuracy and applicability of our proposed RFR algorithm, we trained and tested it on a dataset of laboratory measurements of combustion aerosols. Input variables to the algorithm included the aerosol number size distribution from the Scanning Mobility Particle Sizer, absorption coefficients from the filter-based Tricolor Absorption Photometer, and scattering coefficients from a multiwavelength nephelometer. The RFR algorithm predicted <span class="inline-formula"><i>B</i><sub>abs</sub></span> values within 5 % of the reference <span class="inline-formula"><i>B</i><sub>abs</sub></span> measured by the multiwavelength PASS during the laboratory experiments. Thus, we show that machine learning approaches offer a promising path to correct for biases in long-term filter-based absorption datasets and accurately quantify their variability and trends needed for robust radiative forcing determination.</p>https://amt.copernicus.org/articles/15/4569/2022/amt-15-4569-2022.pdf
spellingShingle J. Kumar
T. Paik
N. J. Shetty
P. Sheridan
A. C. Aiken
M. K. Dubey
R. K. Chakrabarty
Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
Atmospheric Measurement Techniques
title Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
title_full Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
title_fullStr Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
title_full_unstemmed Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
title_short Correcting for filter-based aerosol light absorption biases at the Atmospheric Radiation Measurement program's Southern Great Plains site using photoacoustic measurements and machine learning
title_sort correcting for filter based aerosol light absorption biases at the atmospheric radiation measurement program s southern great plains site using photoacoustic measurements and machine learning
url https://amt.copernicus.org/articles/15/4569/2022/amt-15-4569-2022.pdf
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