Sea ice thermodynamic and dynamic processes in the ocean-sea ice-atmosphere system of the Canadian Arctic.

摘要

Sea ice, by its presence or absence, controls the transfer of energy, mass and momentum between the ocean and atmosphere in the Arctic playing a vital role in the modulation of earth's climate systems. Polynyas are of particular importance in to ocean-atmosphere exchange in the Arctic because they are integral components of the physical and biological nature of the Arctic climate. The aim of this thesis is to investigate snow-covered sea ice volumes from the local to regional scale in the context of thermodynamic and dynamic processes that create them and cause their interaction. Measurement of separate snow and sea ice thickness has in the past been of some difficulty, especially when attempting to obtain spatially distributed samples. Using snow and sea ice physical in situ sampling, a method for remotely sensing separate snow and sea ice thickness using ground penetrating radar has been created to allow for high frequency sampling in time and space. The effect of a melting sea ice volume on ocean stratification is then examined in a Canadian Arctic polynya, where it is determined that the onset of ponding over landfast sea ice surrounding the polynya coincides with the summer stratification of the upper ocean mixed layer. Increasing in scale from local to regional study, the interaction of different sea ice volumes in time and space are examined, including the spatial and temporal evolution and trends of sea ice concentration. Break-up and freeze-up in the Cape Bathurst polynya region are examined to elucidate the variability of break-up and freeze-up in Amundsen Gulf in terms of regional dynamics and the evolving , seasonal ice cover in the area. This work leads to an explanation of the thermodynamic and dynamic processes that cause the interaction of volumes in the region over an annual cycle physical mechanisms that pre-condition, form and maintain the Cape Bathurst polynya. This is an important step in understanding the nature of atmosphere-ocean interaction in an ecologically important transition zone between the Arctic multi-year pack and seasonal sea ice of the Canadian Arctic Archipelago.