Stratospheric forcing of polar surface and ocean circulation response in the Northern and Southern Hemispheres

Stratospheric climate perturbations have the potential to impact high latitude surface climate/ocean circulation if they can influence waves and pressure distributions in the lower troposphere. The degree to which this can be achieved, and the mechanisms involved, are assessed with various versions of the GISS Global Climate Middle Atmosphere model. Of particular interest for the Northern Hemisphere is the possible effect of stratospheric perturbations on the NAO/NAM and sea ice advection into the North Atlantic, with consequences for North Atlantic Deep Water production. In the Southern Hemisphere, a potential primary impact concerns the influence on the SAM and low level meridional wind distribution, which have been leading to contrasting sea ice trends in the southern Bellingshausen Sea and western Ross Sea regions. The influence of stratospheric forcing is compared with that from tropospheric sources of variability (climate change; ENSOs).