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12/7/2018: Séminaire d'Aiko Voigt

Poleward circulation expansion under global warming amplified by rising high-level ice clouds
Quand ? Le 12/07/2018,
de 10:30 à 12:30
Où ? Salle de réunion du LMD/Jussieu (T45-55, 3e étage)
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The regional manifestations of global climate change depend on the response of the large-scale
atmospheric circulation. Recent work showed that a substantial part of future circulation changes
results from clouds and their radiative interactions, and highlighted the role of shortwave cloud-radiative
interactions from low-level clouds. Here, we manipulate clouds in a hierarchy and an ensemble of global
climate models to identify another important mechanism involving longwave radiative interactions of
high-level ice clouds. We find that this mechanism contributes, depending on the model, half or more
to the poleward circulation expansion, and to first order arises from the upward shift of high-level ice clouds
and the associated radiative heating in the upper troposphere. This heating is related to present-day clouds and scales
with the magnitude of global-mean surface warming, providing an opportunity to constrain it from observations.

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