The Effect of Climate Change on Arctic High-Impact Weather Events (ArcChange)

We propose a coordinated Norwegian research project to study how meso-scale high impact weather in the arctic region of the North Atlantic will be affected by future climate change. The project aims at improving our understanding of the regional climate s ystem in the Arctic. The large scale observational activities planned during the IPY period offers a unique opportunity for focused research on the arctic climate. Close links will be made to the Norwegian THORPEX-IPY project, where the main objective is to improve the accuracy of high imact weather forecasts in the Arctic region.THORPEX-IPY is the arctic component of the International program THORPEX (The Observing System Research and Predictability Program). We will improve the treatment of cloud-radiat ion-sea-ice interactions in radiative transfer models for the Arctic and implement new parametrizations of physical processes connected to arctic clouds and sea-ice in numerical models. We will then focus on possible SST feedback mechanisms for the atmosp heric dynamics and on the importantance of the winter-time distributions of sea-ice and SST for the strength and frequency of arctic weather extremes. Finally, by dynamically downscaling selected extreme weather episodes in climate scenarios will be per formed.