Changes of Stratification Structure in the Arctic Ocean in a Regional Ocean Model

Robinson Hordoir, Anne-Britt Sandø, Vidar Lien and W. P. Budgell, Institute of Marine Research Bergen, Oceanography and Climate, Bergen, Norway
The Arctic Ocean is one of the areas of the world that is the most affected by climate change. Recent observations show a decline in sea-ice cover and an increase of the Atlantic water flow towards Fram Strait and the Barents Sea, the latest being often referred as the “Atlantification” of the Arctic ocean. The Arctic ocean is a region of freshwater influence with a specific stratification structure that combines haline and thermal effects, the haline stratification coming from the freshwater input of seasonal sea-ice melting, with the addition of river runoff in coastal areas. Super imposed on the haline stratification, a thermal stratification occurs during spring and summer time in ice-free areas.

With sea-ice vanishing in many areas, the seasonal provision of freshwater disappears leading to a change in the stratification structure from a haline/thermal stratification to a purely thermal stratification. Based on a long term hindcast simulation of a three dimensional regional ocean model, we analyse the changes in mixed layer dynamics in the region of the Barents Sea, and how this process change affects the seasonality of the stratification structure.