scholarly journals Features in wavelength dependence of aerosol absorption observed over central India

2005 ◽  
Vol 32 (13) ◽  
Author(s):  
Dilip Ganguly
Keyword(s):  
Central India ◽  
Wavelength Dependence ◽  
Aerosol Absorption

scholarly journals Satellite-based evidence of wavelength-dependent aerosol absorption in biomass burning smoke inferred from ozone monitoring instrument

2011 ◽  
Vol 11 (3) ◽  
pp. 7291-7319 ◽  
Author(s):  
H. Jethva ◽  
O. Torres
Keyword(s):  
Biomass Burning ◽  
Spectral Dependence ◽  
Central Africa ◽  
Wavelength Dependence ◽  
Carbonaceous Aerosol ◽  
Ozone Monitoring Instrument ◽  
Aerosol Model ◽  
Monitoring Instrument ◽  
Aerosol Absorption ◽  
Ozone Monitoring

Abstract. We provide satellite-based evidence of the spectral dependence of absorption in biomass burning aerosols over South America using near-UV measurements made by Ozone Monitoring Instrument (OMI) during 2005–2007. Currently, OMAERUV aerosol algorithm characterizes carbonaceous aerosol as "gray" aerosol, meaning no wavelength dependence in aerosol absorption. With this assumption, OMI-derived aerosol optical depth (AOD) is found to be over-estimated significantly compared to that of AERONET at several sites during intense biomass burning events (August–September). The assumption on height of aerosols and other parameters seem to be reasonable and unable to explain large discrepancy in the retrieval. The specific ground-based studies have revealed strong spectral dependence in aerosol absorption in the near-UV region that indicates the presence of organic carbon. A new set of OMI aerosol retrieval with assumed wavelength-dependent aerosol absorption in the near-UV region (Absorption Angstrom Exponent λ−2.5 to −3.0) provided much improved retrieval of AOD with significantly reduced bias. Also, the new retrieval of single-scattering albedo is in better agreement with those of AERONET within the uncertainties (Δω=±0.03). The new smoke aerosol model was also found to be valid over the biomass burning region of central Africa and northern India. Together with suggesting vast improvement in the retrieval of aerosol properties from OMI, present study demonstrates the near-UV capabilities of OMI in separating aerosols containing organics from pure black carbon through OMI-AERONET integrated measurements.

scholarly journals Production of particulate brown carbon during atmospheric aging of residential wood-burning emissions

2018 ◽  
Vol 18 (24) ◽  
pp. 17843-17861 ◽  
Author(s):  
Nivedita K. Kumar ◽  
Joel C. Corbin ◽  
Emily A. Bruns ◽  
Dario Massabó ◽  
Jay G. Slowik ◽  
...  
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Wavelength Dependence ◽  
Organic Aerosol ◽  
Geometric Standard Deviation ◽  
Wood Combustion ◽  
Brown Carbon ◽  
Atmospheric Aging ◽  
Aerosol Absorption ◽  
Uv Visible

Abstract. We investigate the optical properties of light-absorbing organic carbon (brown carbon) from domestic wood combustion as a function of simulated atmospheric aging. At shorter wavelengths (370–470 nm), light absorption by brown carbon from primary organic aerosol (POA) and secondary organic aerosol (SOA) formed during aging was around 10 % and 20 %, respectively, of the total aerosol absorption (brown carbon plus black carbon). The mass absorption cross section (MAC) determined for black carbon (BC, 13.7 m2 g−1 at 370 nm, with geometric standard deviation GSD =1.1) was consistent with that recommended by Bond et al. (2006). The corresponding MAC of POA (5.5 m2 g−1; GSD =1.2) was higher than that of SOA (2.4 m2 g−1; GSD =1.3) at 370 nm. However, SOA presents a substantial mass fraction, with a measured average SOA ∕ POA mass ratio after aging of ∼5 and therefore contributes significantly to the overall light absorption, highlighting the importance of wood-combustion SOA as a source of atmospheric brown carbon. The wavelength dependence of POA and SOA light absorption between 370 and 660 nm is well described with absorption Ångström exponents of 4.6 and 5.6, respectively. UV-visible absorbance measurements of water and methanol-extracted OA were also performed, showing that the majority of the light-absorbing OA is water insoluble even after aging.

scholarly journals Spectral absorption properties of atmospheric aerosols

2007 ◽  
Vol 7 (23) ◽  
pp. 5937-5943 ◽  
Author(s):  
R. W. Bergstrom ◽  
P. Pilewskie ◽  
P. B. Russell ◽  
J. Redemann ◽  
T. C. Bond ◽  
...  
Keyword(s):  
Optical Depth ◽  
Atmospheric Aerosols ◽  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectral Absorption ◽  
Solar Absorption ◽  
Airborne Measurements ◽  
Aerosol Absorption

Abstract. We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.

scholarly journals Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment

2016 ◽  
Author(s):  
Stelios Kazadzis ◽  
Panagiotis Ι. Raptis ◽  
Natalia Kouremeti ◽  
Vassilis Amiridis ◽  
Antti Arola ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Composition ◽  
Data Set ◽  
Aerosol Absorption ◽  
Uv Irradiance ◽  
Band Radiometer ◽  
Uv Range

Abstract. We have used total and diffuse UV irradiance measurements with a multi-filter rotating shadow-band radiometer (UVMFR), in order to calculate aerosol absorption properties (Single Scattering Albedo – SSA) in the UV range, for a 5 years period in Athens, Greece. Τhis data set was used as input to a radiative transfer model and the SSA for 368 nm and 332 nm has been calculated. Retrievals from a collocated CIMEL sun-photometer were used to validate the products and study absorption spectral behavior SSA values at these wavelengths. UVMFR SSA together with synchronous,CIMEL-derived, retrievals at 440 nm, show a mean of 0.90, 0.87 and 0.83, with lowest values (higher absorption) towards lower wavelengths. In addition, noticeable diurnal variations of the SSA in all wavelengths are revealed, with amplitudes in up to 0.05. High SSA wavelength dependence is found for cases of low Ångström exponents and also an SSA decrease with decreasing extinction optical depth, suggesting an effect of the different aerosol composition. Dust and Brown Carbon UV absorbing properties were investigated to understand seasonal variability of the results.

scholarly journals Simultaneous observations by sky radiometer and MAX-DOAS for characterization of biomass burning plumes in central Thailand in January–April 2016

2019 ◽  
Vol 12 (1) ◽  
pp. 599-606 ◽  
Author(s):  
Hitoshi Irie ◽  
Hossain Mohammed Syedul Hoque ◽  
Alessandro Damiani ◽  
Hiroshi Okamoto ◽  
Al Mashroor Fatmi ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Surface Concentration ◽  
Wavelength Dependence ◽  
Optical Absorption Spectroscopy ◽  
Near Surface ◽  
Aerosol Absorption ◽  
Volatile Organic Compound Emissions ◽  
Carbon Aerosols ◽  
Central Thailand

Abstract. The first intensive multicomponent ground-based remote-sensing observations by sky radiometer and multi-axis differential optical absorption spectroscopy (MAX-DOAS) were performed simultaneously at the SKYNET Phimai site located in central Thailand (15.18∘ N, 102.56∘ E) from January to April 2016. The period corresponds to the dry season associated with intense biomass burning (BB) activity around the site. The near-surface concentration of formaldehyde (HCHO) retrieved from MAX-DOAS was found to be a useful tracer for absorption aerosols from BB plumes, when BB was the dominant source of HCHO and absorption aerosols over other sources. As the HCHO concentration tripled from 3 to 9 ppbv, the ratio of gaseous glyoxal to HCHO concentrations in daytime decreased from ∼0.04 to ∼0.03, responding presumably to the increased contribution of volatile organic compound emissions from BB. In addition, clear increases in aerosol absorption optical depths (AAODs) retrieved from sky radiometer observations were seen with the HCHO enhancement. At a HCHO of 9 ppbv, AAOD at a wavelength of 340 nm reached as high as ∼0.15±0.03. The wavelength dependence of AAODs at 340–870 nm was quantified by the absorption Ångström exponent (AAE), providing evidence for the presence of brown carbon aerosols at an AAE of 1.5±0.2. Thus, our multicomponent observations around central Thailand are expected to provide unique constraints for understanding physical–chemical–optical properties of BB plumes.

scholarly journals Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment

2016 ◽  
Vol 9 (12) ◽  
pp. 5997-6011 ◽  
Author(s):  
Stelios Kazadzis ◽  
Panagiotis Raptis ◽  
Natalia Kouremeti ◽  
Vassilis Amiridis ◽  
Antti Arola ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Complex Environment ◽  
Aerosol Composition ◽  
Aerosol Absorption ◽  
Uv Irradiance ◽  
Band Radiometer ◽  
Uv Range

Abstract. We have used total and diffuse UV irradiance measurements from a multi-filter rotating shadow-band radiometer (UVMFR) in order to investigate aerosol absorption in the UV range for a 5-year period in Athens, Greece. This dataset was used as input to a radiative transfer model and the single scattering albedo (SSA) at 368 and 332 nm was calculated. Retrievals from a collocated CIMEL sun photometer were used to evaluate the products and study the absorption spectral behavior of retrieved SSA values. The UVMFR SSA, together with synchronous, CIMEL-derived retrievals of SSA at 440 nm, had a mean of 0.90, 0.87 and 0.83, with lowest values (higher absorption) encountered at the shorter wavelengths. In addition, noticeable diurnal variation of the SSA in all wavelengths is shown, with amplitudes up to 0.05. Strong SSA wavelength dependence is revealed for cases of low Ångström exponents, accompanied by a SSA decrease with decreasing extinction optical depth, suggesting varying influence under different aerosol composition. However, part of this dependence for low aerosol optical depths is masked by the enhanced SSA retrieval uncertainty. Dust and brown carbon UV absorbing properties were also investigated to explain seasonal patterns.

scholarly journals Photoacoustic and nephelometric spectroscopy of aerosol optical properties with a supercontinuum light source

2013 ◽  
Vol 6 (12) ◽  
pp. 3501-3513 ◽  
Author(s):  
N. Sharma ◽  
I. J. Arnold ◽  
H. Moosmüller ◽  
W. P. Arnott ◽  
C. Mazzoleni
Keyword(s):  
Optical Properties ◽  
Light Source ◽  
Wavelength Dependence ◽  
Common Salt ◽  
Design Development ◽  
Aerosol Optical Properties ◽  
Scattering Coefficients ◽  
Aerosol Absorption ◽  
Multi Wavelength

Abstract. A novel multi-wavelength photoacoustic-nephelometer spectrometer (SC-PNS) has been developed for the optical characterization of atmospheric aerosol particles. This instrument integrates a white light supercontinuum laser with photoacoustic and nephelometric spectroscopy to measure aerosol absorption and scattering coefficients at five wavelength bands (centered at 417, 475, 542, 607, and 675 nm). These wavelength bands are selected from the continuous spectrum of the laser (ranging from 400–2200 nm) using a set of optical interference filters. Absorption and scattering measurements on laboratory-generated aerosol samples were performed sequentially at each wavelength band. To test the instrument we measured the wavelength dependence of absorption and scattering coefficients of kerosene soot and common salt aerosols. Results were favorably compared to those obtained with a commercial 3-wavelength photoacoustic and nephelometer instrument demonstrating the utility of the SC light source for studies of aerosol optical properties at selected wavelengths. Here, we discuss instrument design, development, calibration, performance and experimental results.

scholarly journals The impact of biogenic carbon sources on aerosol absorption in Mexico City

2009 ◽  
Vol 9 (5) ◽  
pp. 1537-1549 ◽  
Author(s):  
N. A. Marley ◽  
J. S. Gaffney ◽  
M. Tackett ◽  
N. C. Sturchio ◽  
L. Heraty ◽  
...  
Keyword(s):  
Mexico City ◽  
Carbon Sources ◽  
Wavelength Dependence ◽  
Aerosol Absorption ◽  
Biogenic Carbon ◽  
Fine Aerosol ◽  
Field Campaigns ◽  
Photochemical Aging ◽  
The Impact ◽  
Isotopic Measurements

Abstract. In order to determine the wavelength dependence of fine (<1 micron) atmospheric aerosol absorption in the Mexico City area, the absorption Ångstrom exponents (AAEs) were calculated from hourly averages of aerosol absorption measured at seven wavelengths (370, 450, 520, 590, 660, 880, and 950 nm) with an aethalometer during two field campaigns, the Mexico City Metropolitan Area study in April 2003 (MCMA 2003) and the Megacity Initiative: Local and Global Research Observations in March 2006 (MILAGRO). These results were compared to AAEs determined in the laboratory from 850–280 nm (350 points) on 12-h fine aerosol samples collected at the same sites. The aerosol AAEs varied from 0.76 to 1.5 in 2003 and from 0.63 to 1.4 in 2006. The AAE values determined in the afternoon were consistently higher than the corresponding morning values, suggesting the photochemical aging of the aerosols leading to the formation of more highly UV absorbing organic aerosol species in the afternoon. The AAE values were compared to stable and radiocarbon isotopic measurements of the 12-h aerosol samples to determine the sources of the aerosol carbon. The fraction of modern carbon (fM) in the aerosol samples, as determined from

scholarly journals Determination of Aethalometer multiple-scattering enhancement parameters and impact on source apportionment during the winter 2017–2018 EMEP/ACTRIS/COLOSSAL campaign in Milan

2020 ◽  
Author(s):  
Vera Bernardoni ◽  
Luca Ferrero ◽  
Ezio Bolzacchini ◽  
Alice Corina Forello ◽  
Asta Gregorič ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Multiple Scattering ◽  
Filter Material ◽  
Wavelength Dependence ◽  
Optical Source ◽  
Attenuation Coefficients ◽  
Aerosol Absorption ◽  
The Difference ◽  
Absorption Photometer

Abstract. In the frame of the EMEP/ACTRIS/COLOSSAL campaign in Milan during winter 2018, equivalent black carbon measurements using the Aethalometer 31 (AE31), the Aethalometer 33 (AE33), and the Multi-Angle Absorption Photometer (MAAP) were carried out together with levoglucosan analyses on 12-h resolved PM2.5 samples collected in parallel. From AE31 and AE33 data, the loading-corrected aerosol attenuation coefficients (bATN) were calculated at 7 wavelengths (λs, where λ = 370, 470, 520, 590, 660, 880, 950 nm). Aerosol absorption coefficient at 637 nm (babs_MAAP) was determined by MAAP measurements. Furthermore, babs was also measured at 4 wavelengths (405, 532, 635, 780 nm) on the 12-h resolved PM2.5 samples by a polar photometer (PP_UniMI). After comparing PP_UniMI and MAAP results, we exploited PP_UniMI data to evaluate the filter multiple-scattering enhancement parameter at different wavelengths for AE31 and AE33. We obtained instrument- and wavelength-dependent multiple-scattering parameters by linear regression of the Aethalometer bATN against the babs measured by PP_UniMI. We found significant filter material, and hence instrumental, dependence of the multiple-scattering enhancement parameter with the difference up to 30 % between the AE31 and the AE33 tapes. The wavelength dependence and day/night variations were small – the difference between the smallest and largest value was up to 6 %. Data from the different instruments were used as input to the so-called “Aethalometer model” for optical source apportionment and instrument-dependence of the results was investigated. Inconsistencies among the source apportionment were found fixing the AE31 and AE33 multiple-scattering enhancement parameters to their usual values. Opposite, optimised multiple-scattering enhancement parameters led to 5 % agreement among the approaches. Also, the component-apportionment “MWAA model” was applied to the dataset. It resulted less sensitive to the instrument and the number of wavelengths, whereas significant differences in the determination of the absorption Ångström exponent for brown carbon were found (up to 22 %).

scholarly journals Production of particulate brown carbon during atmospheric aging of wood-burning emissions

2018 ◽  
Author(s):  
Nivedita K. Kumar ◽  
Joel C. Corbin ◽  
Emily A. Bruns ◽  
Dario Massabó ◽  
Jay G. Slowik ◽  
...  
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Wavelength Dependence ◽  
Organic Aerosol ◽  
Geometric Standard Deviation ◽  
Wood Combustion ◽  
Brown Carbon ◽  
Atmospheric Aging ◽  
Aerosol Absorption ◽  
Uv Visible

Abstract. We investigate the optical properties of light-absorbing organic carbon (brown carbon) from domestic wood combustion as a function of simulated atmospheric aging. At shorter wavelengths, light absorption by brown carbon from primary organic aerosol (POA) and secondary organic aerosol (SOA) formed during aging was around 10 % and 20 %, respectively, of the total aerosol absorption (brown carbon plus black carbon). The mass absorption cross-section (MAC) determined for black carbon (BC, 13.7 m2 g−1 (geometric standard deviation GSD = 1.1) at 370 nm) was consistent with that recommended by Bond et al. (2006). The corresponding MAC of POA (5.5 m2 g−1 (GSD = 1.2)) was higher than that of SOA (2.4 m2 g−1 (GSD = 1.3)) at 370 nm. However, SOA presents a substantial mass fraction, with a measured average SOA / POA mass ratio after aging of ~ 5 and therefore contributes significantly to the overall light absorption, highlighting the importance of wood-combustion SOA as a source of atmospheric brown carbon. The wavelength dependence of POA and SOA light absorption between 370 nm and 660 nm is well described with absorption Ångström exponents of 4.6 and 5.6, respectively. UV-visible absorbance measurements of water and methanol-extracted OA were also performed showing that the majority of the light-absorbing OA is water insoluble even after aging.

Sign in / Sign up

Export Citation Format

Share Document