Professor Helen Johnson, University of Oxford
What sets the timescale on which the Arctic Ocean adjusts to changes in wind forcing or sea-ice cover?
Changes in Arctic Ocean circulation and freshwater content have the potential to significantly influence regional and global climate. This talk will focus on how quickly the Arctic Ocean responds to a change in sea-ice cover or wind forcing at the ocean surface, and the mechanisms determining the response timescale. I will present evidence from a hierarchy of studies recently carried out in Oxford, from a 1.5 layer reduced gravity model, through idealised numerical ocean model simulations, to analysis of a state-of-the-art coupled climate model control run, showing that (a) the Arctic Ocean and its fresh water content respond to changes in surface forcing on timescales of about a decade, and (b) ocean eddies likely determine this timescale.