EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Remote-sensing of aerosol atmospheric rivers over the southwest Indian Ocean in September 2017: origins, evolution and impacts

Alexandre Baron1,2, Valentin Duflot1,3, Patrick Chazette4, Marco Gaetani5,6,7, Cyrille Flamant5, Juan Cuesta6, Guillaume Payen3, Philippe Keckhut5, and Philippe Goloub8
Alexandre Baron et al.
  • 1Laboratoire de l'Atmosphère et des Cyclones (LACy), UMR 8105, Université de La Réunion - CNRS - Météo-France, Saint-Denis de La Réunion, France (
  • 2Centre National d'Etudes Spatiales (CNES), Toulouse, France
  • 3Observatoire des Sciences de l'Univers de La Réunion (OSU-R), UMS 3365, Saint-Denis de La Réunion, France
  • 4Laboratoire des Sciences du Climat et de l'Environnement, LSCE-IPSL, UMR 8212, Université Paris-Saclay - CEA - CNRS - UVSQ, Gif-sur-Yvette, France
  • 5Laboratoire Atmosphère Milieux Observations Spatiales, LATMOS-IPSL, UMR 8190, Sorbonne Université - UVSQ - CNRS, Paris, France
  • 6Laboratoire Interuniversitaire des Systèmes Atmosphériques, LISA-IPSL, UMR 7583, Université de Paris - UPEC - CNRS, Paris, France
  • 7Scuola Universitaria Superiore IUSS, Pavia, Italy
  • 8Laboratoire d'Optique Atmosphérique (LOA), UMR 8518, Université de Lille - CNRS, Lille, France

In the southern hemisphere, the dry season from June to October coincides with the occurrence of significant fires especially located along the tropical belt in Africa and South America. This fire activity is an important source of aerosols in the tropical troposphere and results in smoke plumes transported across long distances toward area generally aerosol-free. The atmospheric composition over the Indian Ocean is often influenced by biomass burning plumes shaped by the synoptic atmospheric circulation with high pressure over southern Africa and the movement of westerly waves that may embedded cut-off lows. The propagation over the Indian Ocean is then dependent on the position of the Mascarene High. The meandering shape of the plumes is then associated with an aerosol atmospheric river (AAR). Such a phenomenon has been sampled by spaceborne lidars and spectro-radiometers, and even observed above La Réunion (21.1°S, 55.3°E) during September 2017 by a ground-based lidar and a sun-photometer. The Li1200, an operational lidar in the frame of the Atmospheric Physics Reunion Observatory (OPAR), recorded the passage of an AAR during two nights. These measurements allow us to derive both the vertical structures of the plume and some vertically resolved aerosol optical properties. This information was used to constrain Lagrangian modelling tools to identify the pathways and origins of the biomass burning plume. These results have been corroborated by the spaceborne observations of CALIOP and CATS, and the passive sensor MODIS. Reanalysis of ECMWF with atmospheric composition outputs from the Copernicus Atmosphere Monitoring Service (CAMS) supports the understanding of the synoptic conditions leading to the formation of this aerosol plume configuration. We will present our scientific approach and discuss the environmental impact of these AARs in the southwest Indian Ocean.

How to cite: Baron, A., Duflot, V., Chazette, P., Gaetani, M., Flamant, C., Cuesta, J., Payen, G., Keckhut, P., and Goloub, P.: Remote-sensing of aerosol atmospheric rivers over the southwest Indian Ocean in September 2017: origins, evolution and impacts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7808,, 2022.