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Southern Ocean circulation from hydrographic data : a finite difference inverse model

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Harris, JL (1996) Southern Ocean circulation from hydrographic data : a finite difference inverse model. PhD thesis, University of Tasmania.

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Abstract

A finite difference inverse model is developed to investigate the circulation of the Southern Ocean. The circulation of the Southern Ocean is largely unknown, and yet the heat and freshwater transported by the circulation plays an important role in maintaining the global climate [Rintoul 1988].
Previous inverse studies of the Southern Ocean, and inverse studies in general, suffer from relatively poor average spatial resolution [Martel and Wunsch 1993]. This study presents an inverse model of the Southern Ocean (SOINV) that begins to improve the spatial resolution of inverse investigations. In a move away from the quasi-synoptic approach of previous inverse models, the SOINV utilises all available hydrographic data measured between 190,I and 1990 to estimate a time averaged thermal wind circulation that is added to a mean Ekman circulation on a 1° x 1° grid of the Southern Ocean. By applying conservation equations on each 1° x 1° grid, a mass conserving, weakly vorticity conserving circulation of the Southern Ocean is developed that is dynamically consistent with the observations. The SOINV solves 26,945 equations to determine 28,480 unknowns using weighted damped least squares.
By comparing with in-situ observations, it is found that the SOINV circu-lation: underestimated velocities, developed comparable mass transports across sections in the model domain, and was in high qualitative agreement with the observations. The special features of the SOINV circulation are then highlighted by comparing the circulation to satellite measurements, a forward eddy-resolving numerical model and surface velocity estimates. None of these comparisons are possible with more traditional inverse studies. All of these comparisons show that the circulation developed by the inverse model is internally consistent, and is in close agreement with observations.
Using the mass circulation developed by the inverse model, the heat and fresh-water transports are diagnosed. Comparing the heat and freshwater transports highlight that there are some inconsistencies within the global circulation. Despite these inconsistencies, this investigation demonstrates that a finite difference 1°x 1° grid inverse model is possible. The resultant circulation is statistically consistent with the observations and gives a higher average spatial resolution than previous inverse investigations.

Item Type: Thesis (PhD)
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Presents an inverse model of the Southern Ocean (SOINV) that begins to improve the spatial resolution of inverse investigations. It uses all available hydrographic data from 1904 to 1990 to estimate a time-averaged thermal wind circulation that is added to a mean Ekman circulation. The SOINV circulation Is then compared with satellite measurements, a forward eddy-resolving numerical model and surface velocity estimates. Thesis (Ph.D.)--University of Tasmania, 1997. Includes bibliographical references. Presents an inverse model of the Southern Ocean (SOINV) that begins to improve the spatial resolution of inverse investigations. It uses all available hydrographic data from 1904 to 1990 to estimate a time-averaged thermal wind circulation that is added to a mean Ekman circulation. The SOINV circulation Is then compared with satellite measurements, a forward eddy-resolving numerical model and surface velocity estimates

Date Deposited: 09 Dec 2014 00:02
Last Modified: 23 May 2017 04:07
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