Name: Helen Johnson
Affiliation: University of Oxford/University of Bergen
I am an Assistant Professor in the Earth Sciences Department at the University of Oxford. I also hold a 10% adjunct professorship at the University of Bergen. I work to improve our understanding of ocean circulation and the role it plays in the climate system, using fluid dynamics theory, simple and state-of-the-art numerical models and ocean observations. I am particularly interested in the dynamics of the Atlantic and Arctic Oceans.
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.
Arranged date for the seminar talk: Mar 20, 2017