ausblenden:
Schlagwörter:
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Zusammenfassung:
The connection between the El Nino Southern Oscillation (ENSO) and the
Northern polar stratosphere has been established from observations and
atmospheric modeling. Here a systematic inter-comparison of the
sensitivity of the modeled stratosphere to ENSO in Chemistry Climate
Models (CCMs) is reported. This work uses results from a number of the
CCMs included in the 2006 ozone assessment. In the lower stratosphere, the
mean of all model simulations reports a warming of the polar vortex during
strong ENSO events in February-March, consistent with but smaller than the
estimate from satellite observations and ERA40 reanalysis. The anomalous
warming is associated with an anomalous dynamical increase of column ozone
north of 70 degrees N that is accompanied by coherent column ozone
decrease in the Tropics, in agreement with that deduced from the NIWA
column ozone database, implying an increased residual circulation in the
mean of all model simulations during ENSO. The spread in the model
responses is partly due to the large internal stratospheric variability
and it is shown that it crucially depends on the representation of the
tropospheric ENSO teleconnection in the models.
