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SEAS Colloquium in Climate Science (SCiCS)

Thursday, January 31, 2013 - 2:45pm - 3:45pm
Columbia University Morningside Campus Room 214 S.W. Mudd
Martin Juker
Princeton University, Geophysical Fluid Dynamics Laboratory

"Newtonian Cooling 2.0: A new dry GCM setup for a more realistic stratosphere"

Ever since Held & Suarez 1994, Newtonian cooling has proven to be an efficient method for obtaining realistic climatologies in the troposphere, even in an idealized dry GCM. By adding a simple stratospheric structure, Polvani and Kushner (2002) increased the scope of GFDL's dry dynamical core to encompass stratospheric dynamics, meridional overturning circulation, and troposphere - stratosphere exchange. For the past decade, this model has undergone minor updates and additions, but is still widely used in essentially its original form. I will show that for some applications, this model is no longer satisfactory, and present one possible way of improving the stratospheric structure. The new setup will be based on a radiative approach, and result in a more realistic structure of both relaxation temperature and relaxation time in the Newtonian cooling term. I will show how the new setup improves seasonal variability without sacrificing the advantages of the initial 2002 setup.

Hosts: Lorenzo Polvani & Karen Smith