Investigation of Ice Edge Controls

Supervisor

Petra Heil (AAD)

Project Outline

In the Antarctic the seasonal advance and retreat of the sea-ice presents the largest variability in ice-edge position. Further, this seasonal translation of the ice edge is not spatially uniform, instead maximum and minimum positions vary meridionally. Improved knowledge about the physical processes that control the ice edge is important, as the ice edge is a prime location for the occurrence of algal blooms and plankton assemblages, as well being a location where large flux adjustments are required in current generation coupled ice-ocean models. Detailed knowledge of the ice-edge control mechanisms will lead to improved model forecasts of future climate conditions.

The ice-edge advance is associated with the growth of sea ice (thermodynamic process) during the colder seasons, but it may also be triggered and sustained by advection (dynamic process) of thicker, multi-year ice. Wind interaction may enforce or reverse the equatorward movement of the ice edge, while wave interaction generally opposes the equatorward advance of the ice edge. During an equilibrium stage the annual maximum ice-edge position can be maintained by ice advection or by sharp gradients in the oceanic flow and temperature fields, while thermodynamic processes largely determine the ice-edge retreat.

In this study output data from a coupled model is available to be analysed for variability patterns of the Antarctic ice-edge position. Using statistical tools, including EOFs, Fourier transforms, the mechanisms of ice-edge control will be investigated. This will involve dividing the Antarctic sea-ice zone into sub-regions to isolate competing mechanisms. The aim of this study is to separate between thermodynamic and dynamic controls, and to assess how the ice-edge location will change for future climate scenarios.

Contact

Dr Petra Heil or tel +61 3 6226 7243