Studying the Stability of the Antarctic Slope Front in the Commonwealth Sea

P. N. Golovin, N. N. Antipov, and A. V. Klepikov

In 2004–2007 and 2011–2013, oceanography sections with the high spatial resolution were carried out on the shelf and continental slope of the Commonwealth Sea and in the Prydz Bay in the Antarctic. In combination with a fine vertical resolution, this provides an advanced interpretation of the obtained data. It becomes possible to analyze the local thermohaline structure of the baroclinic Antarctic slope front (the ASF) and to investigate its stability. The reliable determination of the ASF characteristics enables to apply the parameterizations and criteria obtained during laboratory experiments for analysis of its stability. The ASF instability is preceded by the local vertical dramatic intensification of the front, where the ASF approaches the pure baroclinic state. Therefore, the local baroclinic instability in the ASF area prevails over the barotropic one at the significant mutual impact of layers (= HASF/Hb  0.3–0.6, Hb is the total depth) and accompanied with the hydrostatic instability. Instability conditions in the frontal zone with a width of ~(1–2)RdL (RdL is local baroclinic deformation radius) relative to the wide ASF (LASF (3–5)RdL) coincide with those of the narrow (intensified) ASF (LASF RdL*). In the case of the runoff of dense Antarctic shelf water, on the shelf edge the realization is possible of the self-oscillatory mechanism of the ASF instability caused by the topographic beta-effect as well as the periodic generation of baroclinic vortices.