HR: 14:10h
AN: OS13D-03    [Abstracts]
TI: The All-Atlantic Temperature-Salinity-Pressure Relation and Regionally Variable Orthobaric Density
AU: * Springer, S R
EM: springer@coas.oregonstate.edu
AF: Oregon State University, COAS Admin Bldg 104 Oregon State University, Corvallis, OR 97331 United States
AU: de Szoeke, R A
EM: szoeke@coas.oregonstate.edu
AF: Oregon State University, COAS Admin Bldg 104 Oregon State University, Corvallis, OR 97331 United States
AB: The availability of WOCE hydrographic data has prompted a careful reexamination of the relationship between temperature, salinity, and pressure in the Atlantic Ocean. Most of the observed thermodynamic properties are arranged onto three two-dimensional manifolds of three-dimensional thermodynamic space: a more saline northern branch and a fresher southern branch, each of which is nearly independent of pressure, and between them a bridge, on which density is nearly uniform at constant pressure. The properties of the branches are crucial to the construction of joint potential density surfaces, patched together at 1000 db intervals, as practiced by Reid. By resolving more finely in pressure (illustrated with 200 db spacing), a finer system of patched potential density surfaces can be obtained, and indeed the continuous limit can be taken to give a form of orthobaric density. Because it is based on the duplicate regional branches, this new form of orthobaric density is regionally differentiated. Using the properties of the bridge waters, a mapping can be devised to link the southern and northern forms of orthobaric density across the boundary between their respective regions of validity. Within the waters of the respective branches the regionally defined orthobaric isopycnals are very nearly material, limited only by inherent irreversible mixing processes. However, where these isopycnals cross the bridge waters, significant, reversible, material exchange across them may occur. In addition, a Montgomery function is defined within each region, but where the subdomains are patched together the Montgomery function is discontinuous. The idea of regional differentiation can also be extended to other ocean basins to create a variable useful for mapping observations or for use as the vertical coordinate in an isopycnal model on a global scale.
DE: 4223 Descriptive and regional oceanography
DE: 4255 Numerical modeling
DE: 4271 Physical and chemical properties of seawater
DE: 4532 General circulation
DE: 4536 Hydrography
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting