Preprints
https://doi.org/10.5194/acp-2021-12
https://doi.org/10.5194/acp-2021-12

  15 Jan 2021

15 Jan 2021

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

Dust Induced Atmospheric Absorption Improves Tropical Precipitations In Climate Models

Yves Balkanski1, Rémy Bonnet2, Olivier Boucher2, Ramiro Checa-Garcia1, and Jérôme Servonnat1 Yves Balkanski et al.
  • 1Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, IPSL, Gif-sur-Yvette, France
  • 2Institut Pierre-Simon Laplace, Sorbonne Université-CNRS, Paris, France

Abstract. The amount of shortwave radiation absorbed by dust has remained uncertain. We have developed a more accurate representation of dust absorption that is based on the observed dust mineralogical composition and accounts for very large particles. We analyze the results from two fully-coupled climate simulations of 100 years in terms of their simulated precipitation patterns against observations. A striking benefit of the new dust optical and physical properties is that tropical precipitations over Sahel, tropical North Atlantic and West Indian Ocean are significantly improved compared to observations, without degrading precipitations elsewhere. This alleviates a persistent bias in earth system models that exhibit a summer African monsoon that does not reach far enough North. We show that the improvement results from a thermodynamical and dynamical response to dust absorption is unrelated to natural variability. Aerosol absorption induces more water vapor advection from the ocean to the Sahel, thereby providing an added supply of moisture available for precipitation. This work thus provides a path towards improving precipitation patterns in these regions by more realistically accounting for both physical and optical properties of the aerosol.

Yves Balkanski 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-2021-12', J.M. Haywood, 04 Feb 2021
  • RC2: 'Comment on acp-2021-12', Johannes Quaas, 09 Feb 2021
  • RC3: 'Comment on acp-2021-12', Anonymous Referee #3, 02 Mar 2021

Yves Balkanski et al.

Yves Balkanski et al.

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Short summary
Earth system models have persistent biases that impinge on our ability to make robust future regional predictions of precipitation. For the last fifteen years, there has been little to no improvement in these biases. This work presents an accurate representation of dust absorption based upon observed dust mineralogical composition and size distribution. The striking result is that the African monsoon is significantly improved compared to observations.
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