Preprints
https://doi.org/10.5194/acp-2021-256
https://doi.org/10.5194/acp-2021-256

  06 Apr 2021

06 Apr 2021

Review status: a revised version of this preprint is currently under review for the journal ACP.

Combining POLDER-3 satellite observations and WRF-Chem numerical simulations to derive biomass burning aerosol properties over the Southeast Atlantic region

Alexandre Siméon1, Fabien Waquet1, Jean-Christophe Péré1, Fabrice Ducos1, François Thieuleux1, Fanny Peers1, Solène Turquety2, and Isabelle Chiapello1 Alexandre Siméon et al.
  • 1Université de Lille, CNRS, UMR 8518, LOA – Laboratoire d’Optique Atmosphérique, F-59000 Lille, France
  • 2LMD/IPSL, Sorbonne Université, ENS, PSL Université, École Polytechnique, Institut Polytechnique de Paris, CNRS, Paris, France

Abstract. Aerosol absorption is a key property to assess the radiative impacts of aerosols on climate at both global and regional scales. The aerosol physico-chemical and optical properties remain not sufficiently constrained in climate models, with difficulties to properly represent both the aerosol load and their absorption properties in clear and cloudy scenes, especially for absorbing biomass burning aerosols (BBA). In this study we focus on biomass burning (BB) particle plumes transported above clouds over the Southeast Atlantic (SEA) region off the southwest coast of Africa, in order to improve the representation of their physico-chemical and absorption properties. The methodology is based on aerosol regional numerical simulations from the WRF-Chem coupled meteorology-chemistry model combined with a detailed inventory of BB emissions and various sets of innovative aerosol remote sensing observations, both in clear and cloudy skies from the POLDER-3/PARASOL space sensor. Current literature indicates that some organic aerosol compounds (OC) called "brown carbon" (BrOC), primarily emitted by biomass combustion absorb the ultraviolet-blue radiation more efficiently than pure black carbon (BC). We exploit this specificity by comparing the spectral dependence of the aerosol single scattering albedo (SSA) derived from the POLDER-3 satellite observations in the 443–1020 nm wavelength range with the SSA simulated for different proportions of BC, OC and BrOC at the source level, considering the homogeneous internal mixing state of particles. These numerical simulation experiments are based on two main constraints: maintaining a realistic aerosol optical depth both in clear and above cloudy scenes and a realistic BC/OC mass ratio. Modelling experiments are presented and discussed to link the chemical composition with the absorption properties of BBA and to provide estimates of the relative proportions of black, organic and brown carbon in the African BBA plumes transported over the SEA region for July 2008. The absorbing fraction of organic aerosols in the BBA plumes, i.e., BrOC, is estimated at 2 to 3 %. The simulated mean SSA are 0.81 (565 nm) and 0.84 (550 nm) in clear and above cloudy scenes respectively, in good agreement with those retrieved by POLDER-3 (0.85 ± 0.05 at 565 nm in clear-sky and at 550 nm above clouds) for the studied period.

Alexandre Siméon et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-256', Anonymous Referee #1, 27 Apr 2021
    • AC1: 'Reply on RC1', Alexandre Siméon, 06 Aug 2021
  • RC2: 'Comment on acp-2021-256', Anonymous Referee #2, 09 Jun 2021
    • AC2: 'Reply on RC2', Alexandre Siméon, 06 Aug 2021
  • RC3: 'Review on acp-2021-256', Anonymous Referee #3, 15 Jun 2021
    • AC3: 'Reply on RC3', Alexandre Siméon, 06 Aug 2021

Alexandre Siméon et al.

Alexandre Siméon et al.

Viewed

Total article views: 574 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
353 208 13 574 1 2
  • HTML: 353
  • PDF: 208
  • XML: 13
  • Total: 574
  • BibTeX: 1
  • EndNote: 2
Views and downloads (calculated since 06 Apr 2021)
Cumulative views and downloads (calculated since 06 Apr 2021)

Viewed (geographical distribution)

Total article views: 608 (including HTML, PDF, and XML) Thereof 608 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 21 Sep 2021
Download
Short summary
For the first time, we accurately modelled the optical properties of the biomass burning aerosols (BBA) observed over the Southeast Atlantic region during their transport above clouds and over their source regions, combining a meteorology coupled with chemistry model (WRF-Chem) with innovative satellite absorbing aerosol retrievals (POLDER-3). Our results suggest low but non negligible brown carbon fraction (3 %) for the chemical composition of the BBA plumes observed over the source regions.
Altmetrics