The role of lee waves for the sensitivity of the Southern Ocean circulation to changing winds — Australian Meteorological and Oceanographic Society
  1. Schedule
  2. Afternoon Tea + Poster Session 2
  3. The role of lee waves for the sensitivity of the Southern Ocean circulation to changing winds

The role of lee waves for the sensitivity of the Southern Ocean circulation to changing winds (#2015)

Luwei Yang 1 2 , Maxim Nikurashin 1 3 , Andy Hogg 3 4 , Bernadette Sloyan 5
  1. University of Tasmania, Battery Point, TASMANIA, Australia
  2. ARC Centre of Excellence for Climate System Science, Sydney , New South Wales, Australia
  3. ARC Centre of Excellence for Climate Extremes, Sydney, New South Wales, Australia
  4. Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory, Australia
  5. CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia

Lee waves, generated by bottom flow-topography interaction, apply momentum stresses to eddy and time mean flows and extract energy from these flows in the deep Southern Ocean. Subsequent propagation and breaking of lee waves contribute to enhanced turbulent mixing observed in the deep Southern Ocean. Lee waves remain unresolved by eddy-resolving global ocean models.

As westerly winds shift poleward and strengthen, the corresponding response of the Southern Ocean circulation has been suggested to be largely regulated by the eddy field. Previous modelling studies of the Southern Ocean response to changing winds have not considered lee waves as a potential energy sink for the eddy field. In this study, we use an idealised model of the Southern Ocean to investigate the sensitivity of the Southern Ocean circulation to changing winds with a lee wave parameterisation. We parameterise lee waves by representing both the lee wave momentum stresses and lee wave-driven diapycnal mixing processes. We carry out and compare experiments with different magnitudes of the wind forcing and analyse the sensitivity of ACC transport and MOC overturning, especially lower cell, to evaluate the role of lee waves for the sensitivity of the Southern Ocean to changing winds. 

 

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