Preprints
https://doi.org/10.5194/acp-2020-1306
https://doi.org/10.5194/acp-2020-1306

  15 Apr 2021

15 Apr 2021

Review status: this preprint is currently under review for the journal ACP.

Sensitivity of low-level clouds and precipitation to anthropogenic aerosol emission in southern West Africa: a DACCIWA case study

Adrien Deroubaix1,2,a, Laurent Menut1, Cyrille Flamant2, Peter Knippertz3, Andreas Fink3, Anneke Batenburg4, Joel Brito5, Cyrielle Denjean6, Cheikh Dione7, Régis Dupuy8, Valerian Hahn9,10, Norbert Kalthoff3, Fabienne Lohou11, Alfons Schwarzenboeck7, Guillaume Siour12, Paolo Tuccella13, and Christiane Voigt9,10 Adrien Deroubaix et al.
  • 1LMD/IPSL, École Polytechnique, Université Paris Saclay, ENS, IPSL Research University; Sorbonne Universités, UPMC Univ Paris 06, CNRS, Palaiseau, France
  • 2LATMOS/IPSL, Sorbonne Université, Université Paris-Saclay & CNRS, Paris, France
  • 3KIT, Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Germany
  • 4Particle Chemistry Department, Johannes Gutenberg University Mainz/Max Planck Institute for Chemistry, Mainz, Germany
  • 5IMT Lille Douai, Université de Lille, SAGE, Lille, France
  • 6CNRM, Centre National de la Recherche Météorologique, UMR3589, CNRS, Météo-France, Toulouse, France
  • 7ACMAD, African Centre of Meteorological Applications for Development, Niamey, Niger
  • 8LAMP, Laboratoire de Météorologie Physique, Université Clermont Auvergne, Aubière, France
  • 9DLR, Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany
  • 10Institut für Physik der Atmosphäre, Universität Mainz, Mainz, Germany
  • 11LA, Laboratoire d Aérologie, University of Toulouse, CNRS, UPS, Toulouse, France
  • 12LISA/IPSL, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université de Paris Est Créteil et Université de Paris Diderot, Institut Pierre Simon Laplace, Créteil, France
  • 13University of L’Aquila, Department of Physical and Chemical Sciences, L’Aquila, Italy
  • anow at: Max Planck Institute for Meteorology, Hamburg, Germany

Abstract. During the West African summer monsoon, pollutants emitted in urbanized coastal areas modify cloud cover and precipitation patterns. The Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa (DACCIWA) field campaign provided numerous aircraft-based and ground-based observations, which are used here to evaluate two experiments made with the coupled WRF-CHIMERE model, integrating both the direct and indirect aerosol effect on meteorology. During one well-documented week (1–7 July 2016), the impacts of anthropogenic aerosols on the diurnal cycle of low-level clouds and precipitation are analyzed in detail using high and moderate intensity of anthropogenic emissions in the experiments. Over the continent and close to major anthropogenic emission sources, the breakup time of low-level clouds is delayed by one hour, and the daily precipitation rate decreased by 7.5 % with the enhanced anthropogenic emission experiment (with high aerosol load). Despite the small modifications on daily average of low-level cloud cover (+2.6 %) with high aerosol load compared to moderate, there is an increase by more than 20 % from 14:00 to 22:00 UTC on hourly average. Moreover, modifications of the modeled low-level cloud and precipitation rate occur far from the major anthropogenic emission sources, to the south over the ocean and to the north up to 11° N. The present study adds evidence to recent findings that enhanced pollution levels in West Africa may reduce precipitation.

Adrien Deroubaix et al.

Status: open (until 10 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1306', Anonymous Referee #1, 23 Apr 2021 reply

Adrien Deroubaix et al.

Adrien Deroubaix et al.

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Short summary
During the summer monsoon in West Africa, pollutants emitted in urbanized areas modify cloud cover and precipitation patterns. We analyze these patterns with the WRF-CHIMERE model integrating the effects of aerosols on meteorology, based on the numerous observations provided by the Dynamics-Aerosol-Climate-Interactions campaign. This study adds evidence to recent findings that increased pollution levels in West Africa delay the breakup time of low-level clouds and reduce precipitation.
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