Structure and Evolution of Thermohaline Staircases in Tropical North Atlantic

• Main Author: Wall, Steven
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA
• Format: Text
• Language: English
• Published: 2007
• Subjects: Physical and Dynamic Oceanography; *CONVECTION; *NORTH ATLANTIC OCEAN; THERMAL PROPERTIES; MATHEMATICAL MODELS; MEDITERRANEAN SEA; WATER MASSES; SALT WATER; TEMPERATE REGIONS; SALINITY; MIXED LAYER(MARINE); EVOLUTION(GENERAL); THESES; *THERMOHALINE STAIRCASES; SFTRE(SALT FINGER TRACER RELEASE EXPERIMENT); SALT FINGERS; C-SALT; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA475915; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA475915

This study explores the dynamics of salt finger convection which occurs when warm, salty water overlies cool and fresh. Salt finger convection is generally observed in mid-latitude regions, particularly in the Atlantic Ocean and Mediterranean Sea, between the hase of the mixed layer and the top of the intermediate water. Active salt fingering is characterized by the appearance of well mixed layers separated by thin high-gradient interfaces, known as thermohaline staircases. The data from the C-SALT, SFTRE and moored profiler experiments are analyzed to determine the origin of the thermohaline staircases and the mechanism for selection of the preferred layer thickness. Comparisons between these observations and models suggested by Radko are made. We use a combination of data analysis and analytical considerations to estimate the vertical heat/salt mixing rates and their dependencies on the large-scale environmental parameters. The three dimensional structure of these staircases and their evolution in time is explained by considering the secondary instabilities of a series of diffusive interfaces and the temporal and spatial structure of the high resolution data. Using a Parabolic Equation model we have investigated the influence of thermohaline staircases on acoustic propagation. Also we experiment the sensitivity of the acoustic variations to changes in frequency and source depth. The original document contains color images.