File:Diapycnal transport and pattern formation in double-diffusive convection (IA diapycnaltranspo1094547939).pdf

This work analyzes the role of double-diffusive convection in constraining diapycnal velocity in the mid-latitude thermocline and in the initiation and maintenance of the deep convection associated with polynya and sea ice thinning events. Previously, no comprehensive high-resolution modeling studies of the possible role of double-diffusion in these areas have been conducted. A series of simulations using a numerical, multi-scale, MPI-based general circulation model is presented to remedy this dearth of knowledge. The effects of turbulent-dominated and purely double-diffusive regimes are compared to dual turbulent/double-diffusive systems and results are used to assess the likely roles of double-diffusion in constraining diapycnal velocity and delaying convection onset in high-latitude regions of marginal water column stability. High-resolution numerical modeling indicates that when both double-diffusion and turbulence are present, the constraints on diapycnal velocity loosen (tighten) with the increase of the fraction of the overall mixing attributed to turbulence (double-diffusion). The results of this study also indicate that double-diffusion could play an important role in delaying the onset of deep convection in the vicinity of Maud Rise in the eastern Weddell Sea, and may contribute to polynya formation and the persistence of interannual sea ice thinning.

Subjects: double-diffusion; diffusive convection; salt fingering; diffusive flux; diapycnal velocity; Weddell Sea polynya