Student Seminar: Mehdi Pasha Karami Arokhloo

Title

Studying the importance of Arctic gateways by using a fully coupled ice-ocean model

Abstract

Studying the Arctic Ocean, as an important component of the climate system, is a challenge because of the presence of sea-ice, multiple gateways, and interaction with the Atlantic Ocean, Pacific Ocean and ice-sheets. The fluxes of heat and freshwater through the Arctic gateways have been suggested to change in the future which can in turn affect the distribution of the Arctic sea-ice, and alter the Atlantic meridional overturning circulation. Here we intend to understand the relative importance of the Bering Strait and the Canadian Arctic Archipelago (CAA) in transporting heat and freshwater fluxes, and the corresponding regions where they affect the most. We use a regional configuration of the fully coupled ice-ocean model, NEMO (Nucleus for European Modelling of the Ocean model) version 3.4 for a set of sensitivity experiments with various gateway configurations inspired by paleogeometries of the Arctic. In order to reduce the degrees of freedom introduced by the presence of multiple straits in the system, we compare our model scenarios with the case in which both Bering and CAA are closed. We show that CAA and Bering Strait have nearly opposite impact on the Arctic Sea ice. While the impact of CAA is more limited to the Arctic, the Bering Strait affects the Atlantic Ocean and plays a role in its zonal density gradient. The results will allow us to better understand the impacts caused by modulation of the Bering Strait and CAA fluxes, and better founded predictions of future changes.