A GCM Study of the Climatic Effect of 1979–1992 Ozone Trend
The climatic effeet of the column ozone trend derived from TOMS data is investigated using an updated Version of GENESIS general circulation model (GCM). The GCM employs a newly constructed ozone climatology that includes longitudinal Variation. In the perturbed Simulation, the O3 trend is assumed to be confined to the lower stratosphere, and imposed in transient from January 1979 to December 1992 to incorporate both seasonal variations and linear year to year changes.
In response to the O3 depletion, the south polar (70–90°S) lower stratosphere experiences a significant cooling trend from September to January, with a peak in November. This cooling is accompanied by lower tropospheric warming. For boreal winter, lower stratospheric cooling trends are also identified in the midlatitudes of both hemispheres. These GCM signals resemble observations, and can be explained in terms of radiative forcing expectations. Over the Arctic, a relatively small O3 loss leads the model stratosphere to warm substantially during November-January. This is followed by a strong cooling in March-May. The result cannot be attributed exclusively to the radiative forcing. Rather it indicates the dominant role of dynamical feedbacks and the importance of atmospheric inertia. Furthermore, the climate responses in the atmosphere and at the surface reveal a pronounced longitudinal contrast, especially over the Arctic where a vigorous pattern analogous to zonal waves 1–2 is identified.
KeywordsMethane Dioxide Microwave Convection Hydroxyl
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