High resolution basin-scale simulations for the Arctic-North Atlantic Oceans

We investigate mechanisms by which freshwater influx (or the lack thereof) from the Arctic might impact the circulation dynamics and hydrography in the North Atlantic. The research is focused on: (1) comparing and contrasting the impact of Arctic freshwater influx to the eastern and western sides of the North Atlantic, (2) determining whether a direct mechanism exists between Arctic freshwater export and evolution of Great Salinity Anomalies (GSAs), and (3) predicting the projected trends and variations in the North Atlantic Ocean based on IPCC projections. In order to address these objectives, we conduct simulations using a high resolution basin-scale ROMS model setup with sea-ice, precipitation and riverine components. The pole shifted model grid is of varying resolution with higher resolution (~5 km) in the North Atlantic and Arctic and lower resolution (~ 50 km) in the Equatorial and South Atlantic. There are 50 non-uniform vertical levels in the model. Analysis of model-derived basin-scale circulation fields from 1985-2007 are presented. In particular we discuss the Beaufort Gyre (BG) “leaking” hypothesis which postulates the set-up of a smaller BG under sustained cyclonic wind stress in contrast to a larger BG under dominant anticyclonic wind stress. The larger BG triggers the “leak” or release of the low salinity pool, which then advects around the northern North Atlantic in the form of a GSA. The sea-ice and freshwater export through the Fram Strait east of Greenland is compared with that through the Canadian Archipelago in a quantitative manner.