Thursday 10 November 11:00 - EARTH SYSTEM PHYSICS - Guest Seminar

[Earth System Physics Section]

EARTH SYSTEM PHYSICS - GUEST SEMINAR
Thursday, 10 November 11:00 hrs
Central area, 2nd floor, ex-SISSA bldg.

Lenka Novakova
Dept. of Meteorology
University of Reading
UK

STORM TRACK LIFECYCLE AND STEADY-STATE BAROCLINIC ADJUSTMENT
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Understanding storm track dynamics is key for reducing some of the major errors in global climate models (GCM). The baroclinic instability that forms storm tracks is found to interact nonlinearly in time with the mean vertical wind shear. This interaction is much like a predator-prey relationship, where baroclinic eddies are the predator that feeds on the wind shear (and thus limits its own growth) and wind shear is in turn replenished by diabatic forcing during less baroclinically active times. This predator-prey relationship manifests itself as quasiperiodic oscillations in time. It has been found that a two-dimensional mathematical system that describes this predator-prey relationship can be used in the steady state to predict the response of storm tracks in a simplified GCM to forcings of the mean flow or of eddies. The perhaps counterintuitive prediction is that in the steady state, forcing the mean flow will affect the eddies but not the mean flow, and dissipating eddies will affect the mean flow but not the eddies. Such a negative feedback system can be applied to other settings, such as oceanic baroclinic instability, convective instability and other predator-prey like systems. This result has implications for the interpretation of responses of GCMs to Arctic warming.

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