Stratosphere-Troposphere Coupling in an Idealized AGCM: Understanding the Stratosphere's Role in Tropospheric Climate

I will discuss the impact of stratospheric variability on the dynamical
coupling between the stratosphere and the troposphere in an idealized
atmospheric General Circulation Model.  The model reveals a robust
relationship between the strength of the wintertime stratospheric polar
vortex and the latitude of the tropospheric jet; a weaker vortex is
associated with an equatorward shift in the tropospheric jet and vice
versa.  This suggests that an adequate representation of the stratosphere
is important for capturing the mean climate and its variability on
intraseasonal timescales.  In particular, I find that stratospheric
variability influences the timescales of variability in the troposphere,
increasing the persistence of the tropospheric annular mode.  This
increase in tropospheric "memory" on intraseasonal time scales may have
implications for both interannual variability and climate change.

Date

22.04.2008

Time

15:15 h

Place

Bundesstr. 53, room 101/102
Seminar Room 101/102, 1st floor, Bundesstr. 53, 20146 Hamburg, Hamburg

Speaker

Edwin Gerber, Columbia University

Organizers


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