UMR 5672

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Dynamics of eddy-driven jets and macroturbulent scales in the atmosphere

Yohai Kaspi (Weizmann Institute)
When May 15, 2017
from 11:00 AM to 12:00 PM
Where Centre Blaise Pascal
Attendees Yohai Kaspi
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We study the dynamics of eddy-driven jets using a high-resolution idealized atmospheric general circulation model (GCM), where we systematically vary Earth’s rotation rate, and thus allow a clear separation between the subtropical and eddy-driven jets. We find that due to asymmetries in baroclinicity across the jet, eddy-driven jets tend to migrate poleward. Furthermore, the migrating jets allow a latitude-by-latitude analysis of the macroturbulent scales controlling the jets. We find that over a wide range of eddy scales and latitudes the jet width scales with the Rhines scale. This is analyzed through partitioning of the barotropic energy spectrum to the role of eddy-mean and eddy-eddy interactions, in transferring energy up- and down-scale. We find that this can explain the observed energy spectrum in the atmosphere. Finally, the role of eddy-eddy interactions is analyzed through comparison to simulations where they are omitted.

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