Joint Seminar: The role of stationary and transient eddies in shaping midlatitude storm tracks and poleward migration of jets

Transient eddies dominate the extratropical transport of heat, momentum, and water vapor. Yet, it is unclear what controls the spatial distribution and longitudinal extent of storm tracks, and the observed tendency of anomalies to migrate poleward in midlatitudes. In this talk, I will discuss the governing dynamics controlling these features in midlatitudes using an idealized moist GCM with a simple representation of moisture, through analyzing a series of simulations with different planetary rotation rates. Varying the rotation rate in the idealized GCM allows separating out properties which depend differently on rotation rate, such as the stationary wavelength, deformation radius and eddy length scales, and allows separating out the subtropical jet and eddy driven jets which are often merged on Earth. I will show that stationary eddies play a fundamental role in shaping transient storm track dynamics through reorganizing baroclinicity downstream of the storm track formation regions. The relative importance of latent heat in the energy budget and its effect on the dynamics will be discussed as well. Zonal wind and vorticity anomalies propagate downstream and poleward due to asymmetries in baroclinic growth across the jets caused by measures of baroclinic growth, such as the Eady growth rate and supercriticality, having a poleward bias due to the sphericity of the planet.

Datum

21.05.2014

Uhrzeit

13:30 Uhr

Ort

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

ReferentIn

Yohai Kaspi, Weizmann Institute of Science

Chair

Bjorn Stevens

Zur Übersicht