Fast and slow shifts of the zonal-mean intertropical convergence zone in response to an idealized anthropogenic aerosol - Archive ouverte HAL Access content directly
Journal Articles Journal of Advances in Modeling Earth Systems Year : 2017

Fast and slow shifts of the zonal-mean intertropical convergence zone in response to an idealized anthropogenic aerosol

, , , (1) , (1) , , , , ,
1
Aiko Voigt
  • Function : Author
Robert Pincus
  • Function : Author
Bjorn Stevens
  • Function : Author
Nicolas Bellouin
  • Function : Author
Anna Lewinschal
  • Function : Author
Brian Medeiros
  • Function : Author
Zhili Wang
  • Function : Author
Hua Zhang
  • Function : Author

Abstract

Previous modeling work showed that aerosol can affect the position of the tropical rain belt, i.e., the intertropical convergence zone (ITCZ). Yet it remains unclear which aspects of the aerosol impact are robust across models, and which are not. Here we present simulations with seven comprehensive atmosphere models that study the fast and slow impacts of an idealized anthropogenic aerosol on the zonal-mean ITCZ position. The fast impact, which results from aerosol atmospheric heating and land cooling before sea-surface temperature (SST) has time to respond, causes a northward ITCZ shift. Yet the fast impact is compensated locally by decreased evaporation over the ocean, and a clear northward shift is only found for an unrealistically large aerosol forcing. The local compensation implies that while models differ in atmospheric aerosol heating, this does not contribute to model differences in the ITCZ shift. The slow impact includes the aerosol impact on the ocean surface energy balance and is mediated by SST changes. The slow impact is an order of magnitude more effective than the fast impact and causes a clear southward ITCZ shift for realistic aerosol forcing. Models agree well on the slow ITCZ shift when perturbed with the same SST pattern. However, an energetic analysis suggests that the slow ITCZ shifts would be substantially more model-dependent in interactive-SST setups due to model differences in clear-sky radiative transfer and clouds. We also discuss implications for the representation of aerosol in climate models and attributions of recent observed ITCZ shifts to aerosol.
Fichier principal
Vignette du fichier
J Adv Model Earth Syst - 2017 - Voigt - Fast and slow shifts of the zonal%u2010mean intertropical convergence zone in response.pdf (3.19 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03727065 , version 1 (22-07-2022)

Licence

Attribution - NonCommercial - ShareAlike - CC BY 4.0

Identifiers

Cite

Aiko Voigt, Robert Pincus, Bjorn Stevens, Sandrine Bony, Olivier Boucher, et al.. Fast and slow shifts of the zonal-mean intertropical convergence zone in response to an idealized anthropogenic aerosol. Journal of Advances in Modeling Earth Systems, 2017, 9, pp.870-892. ⟨10.1002/2016MS000902⟩. ⟨insu-03727065⟩
25 View
3 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More