The Effect of Climate Change on the Sea Ice and Hydrography in Nares Strait

Abstract

A three-dimensional coupled ocean (Hybrid Coordinate Ocean Model; HYCOM) and sea-ice (Community Ice Code; CICE) model were used to simulate the ice cover and hydrography in the Lincoln Sea, Nares Strait and Baffin Bay for the period 1952 to 2080. The first eight years were used to spin up the model. The last 120 years were divided into four-year sub-periods, which have been evaluated and compared in order to estimate the simulated changes. The modelled oceanic volume flux and freshwater fluxes compare well with observations in the present day scenario. The annual volume flux varies, but the 10-year average is approximately 0.8 Sv (1 Sv = 106m3s−1) without any long-term trend. It should be noted that 5 cm were added to the sea surface height in Baffin Bay and Lancaster Sound during the entire simulation. This was done in order to control the volume flux of the control period without changing the variabillity. The freshwater flux increases from approximately 27 mSv in the control scenario to 73 mSv in the future scenario, mainly due to a fresher surface. The magnitude of the annual ice area flux through Nares Strait is higher than expected compared with results from satellite images. This is because the ice arch formed in the southern part of Kane Basin is less stable in the model simulation. The result is a sea-ice area flux of about 100 . This is approximately the same sea-ice area flux as observed in 2007 when the ice arch did not form. The sea-ice area flux from 2040 increases by around 50% because of a lowering of the sea-ice concentration which causes a large reduction in the internal sea-ice strength. The sea-ice volume flux is reduced during the entire period from approximately 200 to around 125 . The simulated sea-ice cover decreases throughout the entire period. The area is still fully ice covered during winter, but the duration of the sea-ice coverage becomes shorter. This leads to a fresher sea surface and a temperature increase of up to 0.5 °C at depths of approximately 200 m. The opening of the North Water Polynya in spring is limited by the reduced lifetime of the ice arch in Kane Basin. However, during some years when the ice arch is stable the polynya opens as expected both in time and place.