Details:

Journal Title:
Journal of Advances in Modeling Earth Systems
Personal Author:
Voigt, Aiko ; Pincus, Robert ; Stevens, Bjorn ; Bony, Sandrine ; Boucher, Olivier ; ... More +
Voigt, Aiko ; Pincus, Robert ; Stevens, Bjorn ; Bony, Sandrine ; Boucher, Olivier ; Bellouin, Nicolas ; Lewinschal, Anna ; Medeiros, Brian ; Wang, Zhili ; Zhang, Hua Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory) ; PSL (Physical Sciences Laboratory)
OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory) ; PSL (Physical Sciences Laboratory) Less -
Description:
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 zonalmean 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 modeldependent 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.
Keywords:
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Aerosols Atmospheric Science Hydrology Mathematical Models
Source:
Journal of Advances in Modeling Earth Systems 9(2), 870-892, 2017
DOI:
https://doi.org/10.1002/2016MS000902
Document Type:
Journal Article
Rights Information:
CC BY-NC-ND
Compliance:
PMC
Main Document Checksum:
[+]
urn:sha256:e42a6a2cf8e11e1abddb9c4658df38070a8505e5c7b940420ad2e5bedd0d1a1a
Download URL:
https://repository.library.noaa.gov/view/noaa/25304/noaa_25304_DS1.pdf
File Type:

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