A multi-wavelength optical set-up for the characterization of carbonaceous particulate matter

Massabò, Dario; Bernardoni, V.; Bove, Maria Chiara; Brunengo, A.; Cuccia, E.; Piazzalunga, A.; Prati, P.; Valli, G.; Vecchi, R.

doi:10.1016/j.jaerosci.2013.02.006

Cited by 41 publications

(46 citation statements)

References 39 publications

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“…This instrument was developed by Massabò et al (2013) and measures the light transmitted through a filter sample (forward hemisphere) and the light reflected at two different angles (backward hemisphere) in a similar configuration to the MAAP. By using a radiative transfer model, the light absorption coefficients can be calculated.…”

Section: Instrumentationmentioning

confidence: 99%

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

et al. 2017

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Abstract. 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 (å ABS ) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct å ABS , 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 å ABS retrieved from offline MWAA measurements.

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Section: Instrumentationmentioning

confidence: 99%

“…In this study, we use a multi-wavelength absorbance analyzer (MWAA), introduced by Massabò et al (2013Massabò et al ( , 2015, to conduct a systematic multi-wavelength evaluation of ambient data. This way we can estimate the impact of the most common and reliable Aethalometer correction schemes on the å ABS uncertainties.…”

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confidence: 99%

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

et al. 2017

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“…Optical transmittance measurements are sometimes added to PTFE measurement suites as a proxy determination for "black carbon" (Cahill et al 1984;Nejedly et al 2003;Cuccia et al 2010;Barraza-Villarreal et al 2011) and, with sufficient spectral resolution, environmental tobacco smoke (Lawless et al 2004;Yan et al 2011). Massabo et al (2013) recently developed a multi-wavelength and multiangle optical system to make off-line MAAP-like absorption measurements on PTFE as well as quartz fiber filters.…”

Section: Ptfe Filters and The Improve Networkmentioning

confidence: 99%

“…The sample presents less optical depth to normally incident than to diffuse irradiance, reflecting a fraction R C R of this collimated beam. The backscattered radiance is approximately diffuse (Massabo et al 2013;Vecchi et al 2014), reflecting the random microstructure of the expanded PTFE membrane. The backscattered laser flux accordingly provides approximately uniform irradiance of the sphere's interior, with a total incident power of about P 0 D h S R C F laser .…”

Section: ¡1mentioning

confidence: 99%

“…The portion of the exitance transmitted from the direct beam peaks at small angles in the forward direction (Massabo et al 2013;Vecchi et al 2014), producing anisotropy that is only partially mitigated by the sphere's diffuse contribution. The degree of such anisotropy varies from sample to sample, modulated by R and R C , and neglecting it greatly simplifies our analysis by making P filter the only variable needed to characterize irradiance of the sample and plate.…”

Section: Intercalibration Of the Sphere And Platementioning

confidence: 99%

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A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

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Trzepla

Hyslop

et al. 2016

Aerosol Science and Technology

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Investigation of black and brown carbon multiple‐wavelength‐dependent light absorption from biomass and fossil fuel combustion source emissions

et al. 2015

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Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 μg m À3 to~0 μg m À3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370 nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520 nm wavelength. The bulk EC MAC EC, λ (average at 520 nm = 9.0 ± 3.7 m 2 g À1; with OC fraction <0.85 =~7.5 m 2 g À1) and the BrC OC mass absorption cross sections (MAC BrC,OC,λ ) were calculated; at 370 nm ultraviolet wavelengths; the MAC BrC,OC,λ ranged from 0.8 m 2 g À1 to 2.29 m 2 g À1 (lowest peat, highest kerosene), while at 520 nm wavelength MAC BrC,OC,λ ranged from 0.07 m2 g À1 to 0.37 m 2 g À1 (lowest peat, highest kerosene/incense mixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

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A multi-wavelength optical set-up for the characterization of carbonaceous particulate matter

Cited by 41 publications

References 39 publications

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

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

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

Investigation of black and brown carbon multiple‐wavelength‐dependent light absorption from biomass and fossil fuel combustion source emissions

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