A novel single-cavity multi-wavelength photoacoustic spectrometer for atmospheric aerosol research

Abstract. The spectral light absorbing behavior of carbonaceous aerosols varies depending on the chemical composition and structure of the particles. A new single-cavity multi-wavelength photoacoustic spectrometer was developed and characterized for measuring absorption coefficients at three wavelengths across the visible spectral range. In laboratory studies, several types of soot with different organic content were generated by a diffusion flame burner and were investigated for changes in mass-specific absorption cross sections (MAC), absorption and scattering Ångström exponents (αabs and αsca), and single scattering albedo (ω). By increasing the organic carbonaceous (OC) content of the aerosol from 50 % to 90 % of the total carbonaceous mass, for 660 nm nearly no change of MAC was found with increasing OC content. In contrast, for 532 nm a significant, and for 445 nm a strong increase of MAC was found with increasing OC content of the aerosol. Depending on the OC content, the Ångström exponents of absorption and scattering as well as the single scattering albedo increased. These laboratory results were compared to a field study at a traffic dominated urban site, which was also influenced by residential wood combustion. For this site a daily average value of αabs(445–660) of 1.9 was found.

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A novel single-cavity three-wavelength photoacoustic spectrometer for atmospheric aerosol research

Atmospheric Measurement Techniques ◽

10.5194/amt-9-5331-2016 ◽

2016 ◽

Vol 9 (11) ◽

pp. 5331-5346 ◽

Cited By ~ 12

Author(s):

Claudia Linke ◽

Inas Ibrahim ◽

Nina Schleicher ◽

Regina Hitzenberger ◽

Meinrat O. Andreae ◽

...

Keyword(s):

Single Scattering ◽

Organic Content ◽

Visible Spectral Range ◽

Single Scattering Albedo ◽

Urban Site ◽

Strong Increase ◽

Carbonaceous Aerosols ◽

Wood Combustion ◽

Photoacoustic Spectrometer ◽

Single Cavity

Abstract. The spectral light-absorbing behavior of carbonaceous aerosols varies depending on the chemical composition and structure of the particles. A new single-cavity three-wavelength photoacoustic spectrometer was developed and characterized for measuring absorption coefficients at three wavelengths across the visible spectral range. In laboratory studies, several types of soot with different organic content were generated by a diffusion flame burner and were investigated for changes in mass-specific absorption cross section (MAC) values, absorption and scattering Ångström exponents (αabs and αsca), and single scattering albedo (ω). By increasing the organic carbonaceous (OC) content of the aerosol from 50 to 90 % of the total carbonaceous mass, for 660 nm nearly no change of MAC was found with increasing OC content. In contrast, for 532 nm a significant increase, and for 445 nm a strong increase of MAC was found with increasing OC content of the aerosol. Depending on the OC content, the Ångström exponents of absorption and scattering as well as the single scattering albedo increased. These laboratory results were compared to a field study at a traffic-dominated urban site, which was also influenced by residential wood combustion. For this site a daily average value of αabs(445–660) of 1.9 was found.

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A comparative evaluation of Aura-OMI and SKYNET near-UV single-scattering albedo products

Atmospheric Measurement Techniques ◽

10.5194/amt-12-6489-2019 ◽

2019 ◽

Vol 12 (12) ◽

pp. 6489-6503

Author(s):

Hiren Jethva ◽

Omar Torres

Keyword(s):

Surface Albedo ◽

Single Scattering ◽

Single Scattering Albedo ◽

Absolute Difference ◽

Urban Site ◽

Ultraviolet Region ◽

Carbonaceous Aerosols ◽

Inversion Algorithm ◽

Ozone Monitoring Instrument ◽

Dust Aerosols

Abstract. The aerosol single-scattering albedo (SSA) retrieved by the near-UV algorithm applied to the Aura Ozone Monitoring Instrument (OMI) measurements (OMAERUV) is compared with an independent inversion product derived from the sky radiometer network SKYNET – a ground-based radiation observation network with sites in Asia and Europe. The present work continues previous efforts to evaluate the consistency between the retrieved SSA from satellite and ground sensors. The automated spectral measurements of direct downwelling solar flux and sky radiances made by the SKYNET Sun-sky radiometer are used as input to an inversion algorithm that derives spectral aerosol optical depth (AOD) and single-scattering albedo (SSA) in the near-UV to near-IR spectral range. The availability of SKYNET SSA measurements in the ultraviolet region of the spectrum allows, for the first time, a direct comparison with OMI SSA retrievals eliminating the need of extrapolating the satellite retrievals to the visible wavelengths as is the case in the evaluation against the Aerosol Robotic Network (AERONET). An analysis of the collocated retrievals from over 25 SKYNET sites reveals that about 61 % (84 %) of OMI–SKYNET matchups agree within the absolute difference of ±0.03 (±0.05) for carbonaceous aerosols, 50 % (72 %) for dust aerosols, and 45 % (75 %) for urban–industrial aerosol types. Regionally, the agreement between the two inversion products is robust over several sites in Japan influenced by carbonaceous and urban–industrial aerosols; at the biomass burning site Phimai in Thailand; and the polluted urban site in New Delhi, India. The collocated dataset yields fewer matchups identified as dust aerosols mostly over the site Dunhuang with more than half of the matchup points confined to within ±0.03 limits. Altogether, the OMI–SKYNET retrievals agree within ±0.03 when SKYNET AOD (388 or 400 nm) is larger than 0.5 and the OMI UV Aerosol Index is larger than 0.2. The remaining uncertainties in both inversion products can be attributed to specific assumptions made in the retrieval algorithms, i.e., the uncertain calibration constant, assumption of spectral surface albedo and particle shape, and subpixel cloud contamination. The assumption of fixed and spectrally neutral surface albedo (0.1) in the SKYNET inversion appears to be unrealistic, leading to underestimated SSA, especially under lower aerosol load conditions. At higher AOD values for carbonaceous and dust aerosols, however, retrieved SSA values by the two independent inversion methods are generally consistent in spite of the differences in retrieval approaches.

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A Comparative Evaluation of Aura-OMI and SKYNET Near-UV Single-scattering Albedo Products

10.5194/amt-2019-174 ◽

2019 ◽

Author(s):

Hiren Jethva ◽

Omar Torres

Keyword(s):

Surface Albedo ◽

Single Scattering ◽

Single Scattering Albedo ◽

Absolute Difference ◽

Urban Site ◽

Ultraviolet Region ◽

Carbonaceous Aerosols ◽

Inversion Algorithm ◽

Ozone Monitoring Instrument ◽

Dust Aerosols

Abstract. The aerosol single-scattering albedo (SSA) retrieved by the near-UV algorithm applied to the Aura/Ozone Monitoring Instrument (OMI) measurements (OMAERUV) is compared with an independent inversion product derived from the sky radiometer network SKYNET-a ground-based radiation observation network span over Asia and Europe. The present work continues our efforts to evaluate the consistency between the retrieved SSA from satellite and ground sensors. The automated spectral measurements of direct downwelling solar flux and sky radiances made by SKYNET Sun-sky radiometer are used as input to an inversion algorithm that derives spectral aerosol optical depth (AOD) and single-scattering albedo (SSA) in the near-UV to near-IR spectral range. The availability of SKYNET SSA measurements in the ultraviolet region of the spectrum allows, for the first time, a direct comparison with OMI SSA retrievals eliminating the need of extrapolating the satellite retrievals to the visible wavelengths as the case in the evaluation against the Aerosol Robotic Network (AERONET). An analysis of the collocated retrievals from over 25 SKYNET sites reveals that about 61 % (84 %) of OMI-SKYNET matchups agree within the absolute difference of ± 0.03 (± 0.05) for carbonaceous aerosols, 50 % (72 %) for dust aerosols, 45 % (75 %) for urban-industrial aerosol types. Regionally, the agreement between the two inversion products was robust over several sites in Japan influenced by carbonaceous and urban-industrial aerosols, at the biomass burning site Phimai in Thailand, and polluted urban site in New Delhi, India. The collocated dataset yields fewer matchups identified as dust aerosols mostly over the site Dunhuang with more than half of the matchup points confined to within ± 0.03 limits. Combinedly, the OMI-SKYNET retrievals agree mostly within ± 0.03 for the AOD (388 or 400 nm) larger than 0.5 and UV Aerosol Index larger than 0.2. The remaining uncertainties in both inversion products can be attributed to specific assumptions made in the retrieval algorithms, i.e., the uncertain calibration constant, assumption of spectral surface albedo and particle shape, and sub-pixel cloud contamination. The assumption of fixed and spectrally neutral surface albedo (0.1) in the SKYNET inversion appears to be unrealistic, leading to a large underestimation of retrieved SSA, especially for low aerosol load conditions. At large AOD values for carbonaceous and dust aerosols, however, retrieved SSA values by the two independent inversion methods are generally consistent in spite of the differences in retrieval approaches.

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CARBONACEOUS AEROSOLS-SINGLE SCATTERING ALBEDO AND EFFECT ON WEATHER HEATING

Particulate Science And Technology ◽

10.1080/02726359608906685 ◽

1996 ◽

Vol 14 (1) ◽

pp. 43-58 ◽

Cited By ~ 1

Author(s):

HAIYIN SUN ◽

DUANE A. JACKSON ◽

MURRAY CLARK ◽

MALAY K. MAZUMDER

Keyword(s):

Single Scattering ◽

Single Scattering Albedo ◽

Carbonaceous Aerosols

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Aerosol light absorption from attenuation measurements of PTFE-membrane filter samples: implications for particulate matter monitoring networks

10.5194/amt-2018-228 ◽

2018 ◽

Author(s):

Apoorva Pandey ◽

Nishit J. Shetty ◽

Rajan K. Chakrabarty

Keyword(s):

Light Absorption ◽

Membrane Filter ◽

Low Cost ◽

Single Scattering ◽

Carbonaceous Aerosols ◽

Monitoring Networks ◽

Absorption Coefficients ◽

Ptfe Membrane ◽

Thick Fiber ◽

Multi Wavelength

Abstract. Mass absorption cross-section (MAC) measurements of atmospherically-relevant aerosols are required to quantify their effect on Earth’s radiative budget. Estimating aerosol light absorption from transmittance and/or reflectance measurements through filter deposits is an attractive option because of ease of deployment in field settings and low cost. These measurements suffer from artifacts that depend on a given filter measurement system and type of aerosol. Empirical correction algorithms are available for commercial instruments equipped with optically-thick fiber filters, but optically-thin filter media have not been characterized in detail. Here, we present empirical relationships between particle light absorption–measured using multi-wavelength integrated photoacoustic spectrometers and nephelometers–and attenuation measurements for polytetrafluoroethylene (PTFE) membrane filter samples of carbonaceous aerosols generated from combustion of diverse biomass fuels and kerosene (surrogate for fossil-fuel combustion). We establish a simple, wavelength-independent formulation for calculating aerosol MAC and absorption coefficients from filter attenuation measurements. We find the ratio between in-situ absorption and bulk attenuation to be inversely proportional to aerosol single scattering albedo. As a case study, we apply our formulations on 2010 attenuation datasets of the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network to quantify the overestimation in their filter-based absorption coefficients.

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Retrieval of Vertical Single-scattering albedo of Asian dust using Multi-wavelength Raman Lidar System

Korean Journal of Remote Sensing ◽

10.7780/kjrs.2013.29.4.7 ◽

2013 ◽

Vol 29 (4) ◽

pp. 415-421 ◽

Cited By ~ 3

Author(s):

Youngmin Noh ◽

Chulkyu Lee ◽

Kwanchul Kim ◽

Sungkyun Shin ◽

Dongho Shin ◽

...

Keyword(s):

Single Scattering ◽

Asian Dust ◽

Single Scattering Albedo ◽

Raman Lidar ◽

Lidar System ◽

Multi Wavelength

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Retrieval of aerosol single-scattering albedo and polarized phase function from polarized sun-photometer measurements for Zanjan's atmosphere

Atmospheric Measurement Techniques ◽

10.5194/amt-6-2659-2013 ◽

2013 ◽

Vol 6 (10) ◽

pp. 2659-2669 ◽

Cited By ~ 12

Author(s):

A. Bayat ◽

H. R. Khalesifard ◽

A. Masoumi

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Atmospheric Aerosols ◽

Phase Function ◽

Single Scattering ◽

Single Scattering Albedo ◽

Angstrom Exponent ◽

Ångström Exponent ◽

Sun Photometer ◽

Ångstrom Exponent

Abstract. The polarized phase function of atmospheric aerosols has been investigated for the atmosphere of Zanjan, a city in northwest Iran. To do this, aerosol optical depth, Ångström exponent, single-scattering albedo, and polarized phase function have been retrieved from the measurements of a Cimel CE 318-2 polarized sun-photometer from February 2010 to December 2012. The results show that the maximum value of aerosol polarized phase function as well as the polarized phase function retrieved for a specific scattering angle (i.e., 60°) are strongly correlated (R = 0.95 and 0.95, respectively) with the Ångström exponent. The latter has a meaningful variation with respect to the changes in the complex refractive index of the atmospheric aerosols. Furthermore the polarized phase function shows a moderate negative correlation with respect to the atmospheric aerosol optical depth and single-scattering albedo (R = −0.76 and −0.33, respectively). Therefore the polarized phase function can be regarded as a key parameter to characterize the atmospheric particles of the region – a populated city in the semi-arid area and surrounded by some dust sources of the Earth's dust belt.

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Six-year source apportionment of submicron organic aerosols from near-continuous measurements at SIRTA (Paris area, France)

10.5194/acp-2019-515 ◽

2019 ◽

Author(s):

Yunjiang Zhang ◽

Olivier Favez ◽

Jean-Eudes Petit ◽

Francesco Canonaco ◽

Francois Truong ◽

...

Keyword(s):

Source Apportionment ◽

Biomass Burning ◽

Ambient Air ◽

Carbonaceous Aerosols ◽

Time Resolved ◽

Pronounced Increase ◽

Paris Area ◽

Multi Wavelength ◽

High Concentrations

Abstract. Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly-time resolved year-round characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of Aerosol Chemical Speciation Monitor (ACSM) and multi-wavelength aethalometer from November 2011 to March 2018 at a background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase of LO-OOA concentrations and contributions (50–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely high concentrations and OA contributions (32–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter, and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about 200 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil fuel and biomass burning black carbon components), and no trend for LO-OOA over the 6+-year investigated period.

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