Arctic Climate Change and Variability Connected to the Stratosphere

The aim of this proposal is to investigate the impact of climate change on stratospheric ozone recovery, using a state-of-the-art, coupled chemistry-climate model (CCM), and, in turn, to analyse the feedbacks of stratospheric ozone changes onto the climat e of the northern high latitudes. Simulations spanning the next 50 years under climate change scenario conditions and appropriate control runs will be done. Exploratory studies will be carried on two polar processes, still poorly represented or missing a ltogether in current CCMs, and which will be under scrutiny during the International Polar Year: I) the role of solar cycle and solar-terrestrial coupling from energetic particle precipitation (EPP), on the stratospheric ozone and nitrogen chemistry II) t he role of very-short-lived bromine compounds on polar ozone depletion. Diagnostic studies will focus on the potential formation of polar stratospheric clouds (PSC), how this PSC potential is affected by changes in the tropospheric circulation and in str atospheric heating rates in the scenario simulations, and the relationship of the PSC potential to ozone depletion. The feedbacks of the stratospheric composition changes and of the solar forcings on the tropospheric climate and the stratosphere-troposphe re coupling at high northern latitudes will also be investigated.