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Dynamically consistent hydrography and absolute velocity in the eastern North Atlantic OceanThe problem of mapping a dynamically consistent hydrographic field and associated absolute geostrophic flow in the eastern North Atlantic between 24 deg and 36 deg N is related directly to the solution of the so-called thermocline equations. A nonlinear optimization problem involving Needler's P equation is solved to find the hydrography and resulting flow that minimizes the vertical mixing above about 1500 m in the ocean and is simultaneously consistent with the observations. A sharp minimum (at least in some dimensions) is found, apparently corresponding to a solution nearly conserving potential vorticity and with vertical eddy coefficient less than about 10(exp -5) sq m/s. Estimates of `residual' quantities such as eddy coefficients are extremely sensitive to slight modifications to the observed fields. Boundary conditions, vertical velocities, etc., are a product of the optimization and produce estimates differing quantitatively from prior ones relying directly upon observed hydrography. The results are generally insensitive to particular elements of the solution methodology, but many questions remain concerning the extent to which different synoptic sections can be asserted to represent the same ocean. The method can be regarded as a practical generalization of the beta spiral and geostrophic balance inverses for the estimate of absolute geostrophic flows. Numerous improvements to the methodology used in this preliminary attempt are possible.
Document ID
19950052566
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wunsch, Carl (Massachusetts Inst. of Tech., Cambridge, MA United States)
Date Acquired
August 16, 2013
Publication Date
July 15, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: C7
ISSN: 0148-0227
Subject Category
OCEANOGRAPHY
Funding Number(s)
CONTRACT_GRANT: NSF OCE-92-05942
CONTRACT_GRANT: NAGW-1048
Distribution Limits
Public
Copyright
Other