Selected aspects of the Arctic sea ice motion and its influence on the ocean

• Main Author: Itkin, Polona
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2014
• Subjects: Arctic; Arctic Ocean; Climate change; Sea ice
• Online Access: http://nbn-resolving.org/urn:nbn:de:gbv:579-opus-1004682

A faithful simulation of the sea ice drift in a coupled sea ice-ocean model is one of the key prerequisites for a reliable simulation of the sea ice, ocean and atmosphere interactions. To achieve this goal we should continue improving model physics and constructing parameterizations for relevant sub-gird processes. Also a validation of the simulations against the observational data is essential. The main aim of this work is to demonstrate the importance of the sea ice motion for the underlaying ocean. In the scope of the ongoing and anticipated Arctic climate change it has been demonstrated that the changes in the atmosphere and ocean have large impacts on the sea ice cover. At present, it is still unclear if the changes in the sea ice motion itself can also have a feedback effect on the ocean. In this work we hypothesize that a change in the sea ice motion can cause significant changes in the ocean properties and circulation. To test the hypothesis we use two sensitivity studies that help to isolate sea ice motion processes and quantify the contribution of the process to the Arctic climate system. Our main results show that the immobile landfast ice in the model simulation shifts the flaw polynya, location of strong winter sea ice and brine production away from the coast in the more saline ocean waters and more brine reaches the Arctic halocline. This strengthens the halocline that shields cold surface waters and sea ice from the warm Atlantic Water layer underneath. In addition we find that a general change in the sea ice internal strength leads to substantial changes in the ocean properties and circulation. Under weaker and more mobile sea ice Atlantic Water layer temperatures are reduced by 0.2 K. The Eurasian basin circulation in the Atlantic Water layer is increased and this leads to the volume transports adjustments at the Arctic Straits. This effect shows that the Arctic sea ice properties and motion are not only important for the Arctic ocean, but may have consequences also for the global ocean ...