Mixing and stratifying processes in the oceanic surface layer and seasonal thermocline
Mixing and stratifying processes in the oceanic surface layer and seasonal thermocline
A 1-dimensional slab model is developed that describes the deepening of the well-mixed surface layer of the ocean when a wind stress is imposed. Two different mechanisms of mixing, turbulent erosion and shear instability, are modelled and tests are conducted to assess their relative roles by comparison with existing models which parametrise one or other of these mechanisms. Dissipation in the surface layer is related to shear production throughout the layer and the surface velocity is related to the wind velocity. Deepening is shown to be dependent on the product of the parameters generated by these relationships and it is shown that the importance of the shear instability mechanism depends on the value of this product. Data from the JASIN 1972 experiment are used to test the models and show that slab models are more successful at mixed layer depth and temperature prediction then a Reynolds stress closure model.A study is made of the entrainment interface in a two-layer flow. Turbulent and wave parameters we're measured from films of an experiment carried out by Santha (1975) and are analysed to determine relationships between wave and turbulent length and velocity scales and bulk scales. The wavelength was not found to depend on mixed layer depth but was found to be related to a length scale associated with turbulent distortions of the interface. Deepening.due to turbulent erosion could not be distinguished from that due to shear instability.
University of Southampton
1977
Wyatt, Lucy Rhiannon
(1977)
Mixing and stratifying processes in the oceanic surface layer and seasonal thermocline.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A 1-dimensional slab model is developed that describes the deepening of the well-mixed surface layer of the ocean when a wind stress is imposed. Two different mechanisms of mixing, turbulent erosion and shear instability, are modelled and tests are conducted to assess their relative roles by comparison with existing models which parametrise one or other of these mechanisms. Dissipation in the surface layer is related to shear production throughout the layer and the surface velocity is related to the wind velocity. Deepening is shown to be dependent on the product of the parameters generated by these relationships and it is shown that the importance of the shear instability mechanism depends on the value of this product. Data from the JASIN 1972 experiment are used to test the models and show that slab models are more successful at mixed layer depth and temperature prediction then a Reynolds stress closure model.A study is made of the entrainment interface in a two-layer flow. Turbulent and wave parameters we're measured from films of an experiment carried out by Santha (1975) and are analysed to determine relationships between wave and turbulent length and velocity scales and bulk scales. The wavelength was not found to depend on mixed layer depth but was found to be related to a length scale associated with turbulent distortions of the interface. Deepening.due to turbulent erosion could not be distinguished from that due to shear instability.
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Published date: 1977
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Local EPrints ID: 460642
URI: http://eprints.soton.ac.uk/id/eprint/460642
PURE UUID: c9d1386d-5fd9-47c4-8382-c7750e8b92c8
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Date deposited: 04 Jul 2022 18:26
Last modified: 04 Jul 2022 18:26
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Author:
Lucy Rhiannon Wyatt
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