evolution of surface properties of the Arctic Ocean influence the radiative energy transfer through the coupled compartments (atmosphere, sea ice, open ocean) of the Arctic climate system. Radiative effects [...] the upper layers of the Arctic Ocean. In particular, the cold halocline layer, which separates warm Atlantic water from the upper ocean mixed layer, appears to be affected by Arctic climate change. On the [...] experiments with a coupled ocean-sea ice model (North Atlantic Arctic Ocean Sea Ice Model, NAOSIM) show a destabilisation of the halocline due to increased freezing in polynyas of Arctic shelf seas. We are planning