Orli Lachmy

(University of Chicago)

Flow regimes of the atmospheric jet stream and their maintenance

What Meteo Colloquium GR UG
When Nov 16, 2016
from 03:30 pm to 04:30 pm
Where 112 Walker Building
Contact Name Steven Feldstein
Contact email
Contact Phone (814) 865-7042
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Orli Lachmy U Chicago 

The jet stream is a river of air flowing from west to east at around 10 kilometers altitude in the extratropics of both hemispheres, interacting with the midlatitude storm tracks. Different states of the jet stream are observed in different years, seasons and geographical locations: sometimes the jet is seen as a relatively steady flow in upper troposphere subtropics and sometimes as a vigorously meandering flow in the midlatitudes. The different states of the jet stream affect the intensity and location of the storm tracks, which has implications for regional weather and climate. We examine in an idealized model study how the state of the jet changes as the energy of the storms is increased, by changing the control parameters of the model. Two regime transitions are found as the storms are strengthened. In the first transition the jet shifts abruptly to higher latitudes and in the second transition the flow shifts from a quasi-linear regime to a turbulent regime. The mechanisms maintaining the time averaged flow and the temporal variability in each regime are analyzed and explained.