We used the Princeton Ocean Model (POM), a
sigma-coordinate ocean model, to investigate the generation of baroclinic tides in the
southern Weddell Sea. This region is the site of water mass interactions that contribute
to the formation of Weddell Sea Bottom Water (WSBW) and Antarctic Bottom Water (AABW).
Thus, the causes of mixing here are of interest in evaluating possible variations in the
production rates of these water masses.
Based on application of empirical models to the modeled barotropic tidal
flow [Robertson et al., 1998], the pycnocline over the
upper continental slope in this region may undergo significant mixing due to shear
instabilities associated with baroclinic tides and other internal gravity waves. We also
expect turbulence in the boundary layer to be significant. To investigate these processes,
we start with a quasi-2-D version of POM,
assuming no variability in the along-slope direction, and considering only the dominant
semidiurnal M2 tide. The parameters of interest to us include:
- steepness of the seabed slope;
- density stratification (including the presence or absence of the summer mixed
layer due to seasonal ice melt);
- horizontal variations in stratification (i.e., the
inclusion of the Shelf/Slope Front); and
- proximity of the upper slope to the critical latitude for M2, i.e.,
the latitude where the M2 tidal frequency equals the local Coriolis frequency, f (about 74.5oS).
These studies will allow us to determine the regions of the Weddell Sea where tide-induced
mixing might be important, guiding both future modeling studies and measurement programs.
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