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Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean

(2020) ATMOSPHERIC CHEMISTRY AND PHYSICS. 20(23). p.14821-14845
Author
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Abstract
We present an investigation of biomass burning (BB) plumes originating from Africa and Madagascar based on measurements of a suite of volatile organic compounds (VOCs), carbon monoxide (CO), ozone (O-3) and nitrogen dioxide (NO2) obtained during the dry season of 2018 and 2019 at the high-altitude Maido observatory (21.1 degrees S, 55.4 degrees E, 2160 m a.s.l.), located on the remote island of La Reunion in the south-west Indian Ocean (SWIO). Biomass burning plume episodes were identified from increased acetonitrile (CH3CN) mixing ratios. Enhancement ratios (EnRs) - relative to CO - were calculated from in situ measurements for CH3CN, acetone (CH3COCH3), formic acid (HCOOH), acetic acid (CH3COOH), benzene (C6H6), methanol (CH3OH) and O-3. We compared the EnRs to emission ratios (ERs) - relative to CO - reported in the literature in order to estimate loss or production of these compounds during transport. For CH3CN and CH3COOH, the calculated EnRs are similar to the ERs. For C6H6 and CH3OH, the EnR is lower than the ER, indicating a net sink of these compounds which was found to be in line with the expected atmospheric lifetime. For CH3COCH3 and HCOOH, the calculated EnRs are larger than the ERs. The discrepancy reaches an order of magnitude for HCOOH (18-34 pptv ppbv(-1) compared to 1.8-4.5 pptv ppbv(-1)). This points to significant secondary production of HCOOH during transport. The Copernicus Atmospheric Monitoring Service (CAMS) global model simulations reproduce the temporal variation of CO mixing ratios well at the observatory but underestimate O-3 and NO2 mixing ratios in the plumes by on average 16 ppbv and 60 pptv respectively. This discrepancy between modelled and measured O-3 mixing ratios was attributed to (i) large uncertainties in VOC and NOx (NO + NO2) emissions due to BB in CAMS and (ii) misrepresentation of NOx recycling in the model during transport. Finally, transport of pyrogenically emitted CO is calculated with FLEXPART in order to (i) determine the mean plume age during the intrusions at the observatory and (ii) estimate the impact of BB on the pristine marine boundary layer (MBL). By multiplying the excess CO in the MBL with inferred EnRs at the observatory, we calculated the expected impact of BB on CH3CN, CH3COCH3, CH3OH and C6H6 concentrations in the MBL. These excesses constitute increases of similar to 20 %-150 % compared to background measurements in the SWIO MBL reported in the literature.
Keywords
Atmospheric Science, DISPERSION MODEL FLEXPART, VOLATILE ORGANIC-COMPOUNDS, REACTION MASS-SPECTROMETRY, ISLAND 21-DEGREES S, REUNION ISLAND, FORMIC-ACID, TRACE GASES, MAX-DOAS, IN-SITU, SEASONAL-VARIATIONS

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MLA
Verreyken, Bert, et al. “Characterisation of African Biomass Burning Plumes and Impacts on the Atmospheric Composition over the South-West Indian Ocean.” ATMOSPHERIC CHEMISTRY AND PHYSICS, vol. 20, no. 23, 2020, pp. 14821–45, doi:10.5194/acp-20-14821-2020.
APA
Verreyken, B., Amelynck, C., Brioude, J., Müller, J.-F., Schoon, N., Kumps, N., … Stavrakou, T. (2020). Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean. ATMOSPHERIC CHEMISTRY AND PHYSICS, 20(23), 14821–14845. https://doi.org/10.5194/acp-20-14821-2020
Chicago author-date
Verreyken, Bert, Crist Amelynck, Jérôme Brioude, Jean-François Müller, Niels Schoon, Nicolas Kumps, Aurélie Colomb, et al. 2020. “Characterisation of African Biomass Burning Plumes and Impacts on the Atmospheric Composition over the South-West Indian Ocean.” ATMOSPHERIC CHEMISTRY AND PHYSICS 20 (23): 14821–45. https://doi.org/10.5194/acp-20-14821-2020.
Chicago author-date (all authors)
Verreyken, Bert, Crist Amelynck, Jérôme Brioude, Jean-François Müller, Niels Schoon, Nicolas Kumps, Aurélie Colomb, Jean-Marc Metzger, Christopher F. Lee, Theodore K. Koenig, Rainer Volkamer, and Trissevgeni Stavrakou. 2020. “Characterisation of African Biomass Burning Plumes and Impacts on the Atmospheric Composition over the South-West Indian Ocean.” ATMOSPHERIC CHEMISTRY AND PHYSICS 20 (23): 14821–14845. doi:10.5194/acp-20-14821-2020.
Vancouver
1.
Verreyken B, Amelynck C, Brioude J, Müller J-F, Schoon N, Kumps N, et al. Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean. ATMOSPHERIC CHEMISTRY AND PHYSICS. 2020;20(23):14821–45.
IEEE
[1]
B. Verreyken et al., “Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean,” ATMOSPHERIC CHEMISTRY AND PHYSICS, vol. 20, no. 23, pp. 14821–14845, 2020.
@article{8682856,
  abstract     = {{We present an investigation of biomass burning (BB) plumes originating from Africa and Madagascar based on measurements of a suite of volatile organic compounds (VOCs), carbon monoxide (CO), ozone (O-3) and nitrogen dioxide (NO2) obtained during the dry season of 2018 and 2019 at the high-altitude Maido observatory (21.1 degrees S, 55.4 degrees E, 2160 m a.s.l.), located on the remote island of La Reunion in the south-west Indian Ocean (SWIO). Biomass burning plume episodes were identified from increased acetonitrile (CH3CN) mixing ratios. Enhancement ratios (EnRs) - relative to CO - were calculated from in situ measurements for CH3CN, acetone (CH3COCH3), formic acid (HCOOH), acetic acid (CH3COOH), benzene (C6H6), methanol (CH3OH) and O-3. We compared the EnRs to emission ratios (ERs) - relative to CO - reported in the literature in order to estimate loss or production of these compounds during transport. For CH3CN and CH3COOH, the calculated EnRs are similar to the ERs. For C6H6 and CH3OH, the EnR is lower than the ER, indicating a net sink of these compounds which was found to be in line with the expected atmospheric lifetime. For CH3COCH3 and HCOOH, the calculated EnRs are larger than the ERs. The discrepancy reaches an order of magnitude for HCOOH (18-34 pptv ppbv(-1) compared to 1.8-4.5 pptv ppbv(-1)). This points to significant secondary production of HCOOH during transport. The Copernicus Atmospheric Monitoring Service (CAMS) global model simulations reproduce the temporal variation of CO mixing ratios well at the observatory but underestimate O-3 and NO2 mixing ratios in the plumes by on average 16 ppbv and 60 pptv respectively. This discrepancy between modelled and measured O-3 mixing ratios was attributed to (i) large uncertainties in VOC and NOx (NO + NO2) emissions due to BB in CAMS and (ii) misrepresentation of NOx recycling in the model during transport. Finally, transport of pyrogenically emitted CO is calculated with FLEXPART in order to (i) determine the mean plume age during the intrusions at the observatory and (ii) estimate the impact of BB on the pristine marine boundary layer (MBL). By multiplying the excess CO in the MBL with inferred EnRs at the observatory, we calculated the expected impact of BB on CH3CN, CH3COCH3, CH3OH and C6H6 concentrations in the MBL. These excesses constitute increases of similar to 20 %-150 % compared to background measurements in the SWIO MBL reported in the literature.}},
  author       = {{Verreyken, Bert and Amelynck, Crist and Brioude, Jérôme and Müller, Jean-François and Schoon, Niels and Kumps, Nicolas and Colomb, Aurélie and Metzger, Jean-Marc and Lee, Christopher F. and Koenig, Theodore K. and Volkamer, Rainer and Stavrakou, Trissevgeni}},
  issn         = {{1680-7316}},
  journal      = {{ATMOSPHERIC CHEMISTRY AND PHYSICS}},
  keywords     = {{Atmospheric Science,DISPERSION MODEL FLEXPART,VOLATILE ORGANIC-COMPOUNDS,REACTION MASS-SPECTROMETRY,ISLAND 21-DEGREES S,REUNION ISLAND,FORMIC-ACID,TRACE GASES,MAX-DOAS,IN-SITU,SEASONAL-VARIATIONS}},
  language     = {{eng}},
  number       = {{23}},
  pages        = {{14821--14845}},
  title        = {{Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean}},
  url          = {{http://dx.doi.org/10.5194/acp-20-14821-2020}},
  volume       = {{20}},
  year         = {{2020}},
}

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