Wednesday, 6 November 2002: 2:20 PM
Tropospheric response to stratospheric perturbations in a relatively simple general circulation model
The sensitivity of the tropospheric extratropical circulation to
thermal perturbations of the polar stratosphere is examined in a dry
primitive equation general circulation model with zonally symmetric
forcing and boundary conditions. For sufficiently strong cooling of
the polar winter stratosphere, the winter-hemisphere tropospheric jet
shifts polewards and strengthens markedly at the surface; this is
accompanied by a drop in surface pressure at high latitudes in the
same hemisphere. In addition, this extratropical tropospheric
response is found to be very similar to the model's leading pattern of
internal variability. These results are tested for robustness at
several horizontal and vertical resolutions, and the same tropospheric
response is observed at all but the lowest resolution tested. The
behavior of this relatively simple model is broadly consistent with
recent observational and modeling studies of trends in extratropical
atmospheric variability.
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