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Title: Dispersal in shallow seas inferred from remotely-sensed infra-red imagery
Author: Daniels, John Wyn
ISNI:       0000 0001 3404 1386
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1986
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This work is an attempt to apply remotely-sensed infra-red radiance measurements to the study of dispersal processes in the shallow, tidally-dominated regime of the English Channel and Southern Bight. Various deficiencies inherent in raw imagery from the spaceborne Advanced Very High Resolution Radiometer (AVHRR) are identified and the corresponding corrective strategies reviewed and discussed. In particular, an algorithm to map an arbitrarily orientated image onto a standard geographical grid is developed and included as part of an integrated processing shceme which produces maps of sea-surface temperature from the content of the AVHRR data stream. The sea-surface temperature patterns thus obtained are then applied to a two dimensional finite-difference model of the advective-diffusive processes occurring over the winter of 1983-84, an interval which coincides with a good time series of satellite imagery. By matching the model-predicted thermal fields at various stages during the integration of the corresponding observed fields, the degrees of success of adopting one of a number of parameterisations of horizontal mixing is assessed. The theoretical work of Bowden (1965) and observational results of Talbot and Talbot (1974) suggest that horizontal mixing in this region may be due, in large part, to the interaction of turbulent vertical eddies and vertical shear in the tidal streams. Here, Bowden's method is extended to the case of a two-dimensional tidal current vector which varies in time. This provides one possible mechanism for mixing and it is compared by means of the model results with others which assume (a) no diffusion and (b) diffusion due to horizontal eddies with various typical length-scales. The shortcomings of the model results are assessed in the light of inadequacies in the meteorological data used for calculating the surface heat fluxes; it transpires that these fluxes strongly influence not only the gross temperature of the basin but also the spatial structure of the thermal field. The simulated results of an instantaneous tracer discharge in the Dover Straits under varying dispersal conditions are also prevented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Sea mapping by infra-red image