| dc.description.abstract | The Weddell Polynya, a large hole in the Antarctic sea ice, reappeared in 2017.
The polynya forms due to deep convection, which is caused by static instability of the
water column. Observations and model studies show periodic heat accumulation in
the subsurface layer prior to a polynya. This heat accumulation could be caused by
internal ocean dynamics: the Southern Ocean Mode. Periodic subsurface heat and
salt accumulation could be the major driver in causing periodic deep convection, which
is in contrast with earlier studies. These studies focus on surface processes, and see
the polynya as an irregular event. In this study a simple convective model is used to
look into this contrast. Model simulations excluding and including periodic subsurface
heat and salt fluxes have been performed. Multiple polynya events were only simulated
in the model set up including subsurface fluxes. The dominant frequency for polynya
events in these simulations equals the frequency of the subsurface heat and salt
accumulation. This frequency is still visible in runs with white noise added to the
freshwater flux, showing the importance and dominance of the subsurface forcing. In
combination with earlier studies, this study suggests that periodic subsurface processes
are most dominant and govern the initial formation and periodicity of the Weddell
Polynya. | |
