Impact of Polar Ozone Loss on the Troposphere
The chapter reviews the evidence for the influence of Antarctic and Arctic ozone changes on the troposphere and ocean, and the mechanisms underlying this coupling. Antarctic ozone depletion has driven a cooling and strengthening of the polar vortex in austral spring. Models and observations show that this change has also been associated with a strengthening and poleward shift of the midlatitude westerly winds in the Southern Hemisphere troposphere in austral summer, as well as a cooling of the Antarctic troposphere. Antarctic ozone depletion has been associated with summer trends in surface temperature over Antarctica, precipitation over the southern hemisphere, Southern Ocean circulation, and ocean-atmosphere fluxes of carbon dioxide over the Southern Ocean. Both radiative and dynamical mechanisms are thought to be involved in communicating the response to stratospheric ozone depletion to the troposphere. In the Arctic there is some modeling evidence suggestive of a link between ozone depletion and tropospheric circulation changes, but due to the weaker ozone trends and larger internal variability, no such relationship has been identified in the observations.