Structure and Dynamics of the Thermohaline Staircases in the Beaufort Gyre

• Main Author: Wilson, Ana L.
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA
• Format: Text
• Language: English
• Published: 2007
• Subjects: Physical and Dynamic Oceanography; Fluid Mechanics; *THERMAL PROPERTIES; *CONVECTION; *OCEANS; *ARCTIC REGIONS; *GRADIENTS; *COLD WATER; MATHEMATICAL MODELS; DATA PROCESSING; VERTICAL ORIENTATION; CLIMATE; SALTS; SALINITY; LAW ENFORCEMENT; HEAT FLUX; MIXED LAYER(MARINE); BUDGETS; NAVAL RESEARCH; SOUND TRANSMISSION; FRESH WATER; ENVIRONMENTS; FLUX(RATE); *DIFFUSIVE CONVECTION; *ARCTIC STAIRCASE; *DIFFUSIVE FLUXES; DIFFUSIVE LAYERING; Arctic
• Online Access: http://www.dtic.mil/docs/citations/ADA474381; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA474381

This study explores the dynamics of diffusive convection which occurs when cold, fresh water overlies warm and salty. The primary convective regime in the Arctic region is characterized by the spontaneous formation of well mixed layers separated by thin high-gradient interfaces known as thermohaline staircases. Data analysis and analytical considerations are used to estimate the vertical heat/salt mixing rates and their dependencies on the large-scale environmental parameters. Based on the analysis of Beaufort staircases, we suggest that the layer thickness, as well as the vertical heat/salt fluxes, is controlled by the patterns of merging events in which relatively small steps are systematically eliminated. Significant concerns are raised with regard to the direct extrapolation of laboratory derived flux laws to ocean conditions. An alternative method of analysis is proposed which involves recalibration of the laboratory-derived flux laws for the oceanic conditions. Extrapolated diffusive convective fluxes are in the range of 1-6 Wm^-2, comparable to magnitude of fluxes currently unaccounted for in the Arctic heat budget. We propose that the parameterizations of the diffusive fluxes in thermohaline staircases can be used to enhance understanding of Arctic climate changes and predictive capabilities of large-scale numerical models. Preliminary findings are indicative of the importance of diffusive convection for sound propagation in the Arctic region the problem of great interest for various Naval research applications in the area. The original document contains color images.