Evidence of a dual African and Australian biomass burning influence on the vertical distribution of aerosol and carbon monoxide over the southwest Indian Ocean basin in early 2020 - UFR Sciences et technologies - Université de La Réunion Accéder directement au contenu
Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2024

Evidence of a dual African and Australian biomass burning influence on the vertical distribution of aerosol and carbon monoxide over the southwest Indian Ocean basin in early 2020

Alexandre Baron
Marion Ranaivombola
Tristan Millet
  • Fonction : Auteur
Thierry Portafaix
  • Fonction : Auteur
Valentin Duflot
  • Fonction : Auteur
Mahesh Kumar Sha
Pierre-François Coheur
  • Fonction : Auteur
Michaël Sicard
Tetsu Sakai
Richard Querel
Ben Liley
Dan Smale
Isamu Morino
Osamu Uchino
  • Fonction : Auteur
Tomohiro Nagai
  • Fonction : Auteur
Penny Smale
John Robinson
  • Fonction : Auteur
Hassan Bencherif
  • Fonction : Auteur

Résumé

Abstract. During the 2020 austral summer, the pristine atmosphere of the southwest Indian Ocean (SWIO) basin experienced significant perturbations. This study examines the variability of aerosols and carbon monoxide (CO) over this remote oceanic region and investigates the underlying processes in the upper troposphere–lower stratosphere (UT-LS). Aerosol profiles in January and February 2020 revealed a multi-layer structure in the tropical UT-LS. Numerical models – the FLEXible PARTicle dispersion model (FLEXPART) and the Modèle Isentropique de transport Mésoéchelle de l'Ozone Stratosphérique par Advection (MIMOSA) – indicated that the lower-stratospheric aerosol content was influenced by the intense and persistent stratospheric aerosol layer generated during the 2019–2020 extreme Australian bushfire events. A portion of this layer was transported eastward by prevailing easterly winds, leading to increased aerosol extinction profiles over Réunion on 27 and 28 January. Analysis of advected potential vorticity revealed isentropic transport of air masses containing Australian biomass burning aerosols from extratropical latitudes to Réunion at the 400 K isentropic level on 28 January. Interestingly, we found that biomass burning (BB) activity in eastern Africa, though weak during this season, significantly influenced (contributed up to 90 % of) the vertical distribution of CO and aerosols in the upper troposphere over the SWIO basin. Ground-based observations at Réunion confirmed the simultaneous presence of African and Australian aerosol layers. This study provides the first evidence of African BB emissions impacting the CO and aerosol distribution in the upper troposphere over the SWIO basin during the convective season.
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hal-04649233 , version 1 (16-07-2024)

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Nelson Bègue, Alexandre Baron, Gisèle Krysztofiak, Gwenaël Berthet, Corinna Kloss, et al.. Evidence of a dual African and Australian biomass burning influence on the vertical distribution of aerosol and carbon monoxide over the southwest Indian Ocean basin in early 2020. Atmospheric Chemistry and Physics, 2024, 24 (13), pp.8031-8048. ⟨10.5194/acp-24-8031-2024⟩. ⟨hal-04649233⟩
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