Monday, 17 June 2013
Bellevue Ballroom (The Hotel Viking)
Unlike the near complete destruction of stratospheric ozone in the Antarctic every spring, chemical ozone destruction in the Arctic stratosphere in winter-spring is highly variable from year to year. Most global climate models (GCMs) prescribe the seasonal cycle of ozone but do not include its interannual variability. Here, we investigate the extent to which this variability in Arctic ozone destruction dynamically influences the surface climate of the Northern Hemisphere. We run 50-year integrations with prescribed low (LO; -15% relative to the 1980-2009 climatological model ozone) and high (HI; +15%) stratospheric ozone from 50-90N using the Community Atmosphere Model Version 3 (CAM3). The most striking differences between the two integrations occur in April and May with the final warming being delayed by 14 days in the LO integration relative to the HI integration. In the zonal mean, the LO minus HI response resembles the positive phase of the Northern Annular Mode with low (high) sea level pressure over the poles (mid-latitudes) and a poleward shift of the mid-latitude jet. The poleward shifted jet in the LO integration is accompanied by a significant poleward shift in extratropical precipitation in spring. The modeling results are similar to composite analysis of low and high Arctic ozone years in the MERRA reanalysis.
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