Growth, Structure and Prediction of the Thermal Internal Boundary Layer

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dc.contributor.advisorKeen, Cecilen_ZA
dc.contributor.authorComrie, Andrew Charlesen_ZA
dc.date.accessioned2014-09-05T12:37:40Z
dc.date.available2014-09-05T12:37:40Z
dc.date.issued1988en_ZA
dc.description.abstractThe Thermal internal Boundary Layer (TIBL) is a dynamic and turbulent mesoscale feature of the coastal atmosphere that forms over the land during conditions of onshore flow. The TIBL develops as an adjustment of the atmospheric boundary layer to the discontinuities of temperature and roughness that occur at the interface between the underlying marine and terrestrial surfaces. The resulting formation of a characteristically convex mixed layer below relatively stable air aloft has serious implications for the dispersion of pollutants in shoreline environments. Although a wide range of research relating to various features of the TIBL may be found in the literature, relatively few broadly-based studies have been performed. This study has employed both airborne and surface measurements to obtain a comprehensive spatial and temporal data set, in order to elucidate aspects of the characteristic structure and behaviour of the TIBL. TIBL growth was found to follow a diurnal pattern, the initially irregular boundary becoming more uniform during the day as a steady balance between various factors was achieved. The TIBL was associated with a layer of uniform wind speed anti direction flowing perpendicular to the coastline, within which warmer temperatures and changes in relative humidity and moisture content were observed. The temperature structure of the onshore flow strongly influenced the intensity of turbulence encountered in the TIBL and the degree of entrainment aloft. Patterns of turbulent properties displayed significant increases in the TIBL, which were relatively abrupt near the surface and more gradual towards the top of the TIBL. Measurements of sensible heat flux revealed strong undulations in TIBL structure due to transitory eddies and thermal upcurrents. Certain theoretically based predictive equations of TIBL height displayed the best overall performance out of eight selected models, and some promise was shown by an empirical formulation. TIBL development was generally complex and irregular within the first few kilometres of the shore, while further inland more regular TIBL formation enabled the relatively accurate observation and prediction of TIBL height.en_ZA
dc.identifier.apacitationComrie, A. C. (1988). <i>Growth, Structure and Prediction of the Thermal Internal Boundary Layer</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science. Retrieved from http://hdl.handle.net/11427/6920en_ZA
dc.identifier.chicagocitationComrie, Andrew Charles. <i>"Growth, Structure and Prediction of the Thermal Internal Boundary Layer."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1988. http://hdl.handle.net/11427/6920en_ZA
dc.identifier.citationComrie, A. 1988. Growth, Structure and Prediction of the Thermal Internal Boundary Layer. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Comrie, Andrew Charles AB - The Thermal internal Boundary Layer (TIBL) is a dynamic and turbulent mesoscale feature of the coastal atmosphere that forms over the land during conditions of onshore flow. The TIBL develops as an adjustment of the atmospheric boundary layer to the discontinuities of temperature and roughness that occur at the interface between the underlying marine and terrestrial surfaces. The resulting formation of a characteristically convex mixed layer below relatively stable air aloft has serious implications for the dispersion of pollutants in shoreline environments. Although a wide range of research relating to various features of the TIBL may be found in the literature, relatively few broadly-based studies have been performed. This study has employed both airborne and surface measurements to obtain a comprehensive spatial and temporal data set, in order to elucidate aspects of the characteristic structure and behaviour of the TIBL. TIBL growth was found to follow a diurnal pattern, the initially irregular boundary becoming more uniform during the day as a steady balance between various factors was achieved. The TIBL was associated with a layer of uniform wind speed anti direction flowing perpendicular to the coastline, within which warmer temperatures and changes in relative humidity and moisture content were observed. The temperature structure of the onshore flow strongly influenced the intensity of turbulence encountered in the TIBL and the degree of entrainment aloft. Patterns of turbulent properties displayed significant increases in the TIBL, which were relatively abrupt near the surface and more gradual towards the top of the TIBL. Measurements of sensible heat flux revealed strong undulations in TIBL structure due to transitory eddies and thermal upcurrents. Certain theoretically based predictive equations of TIBL height displayed the best overall performance out of eight selected models, and some promise was shown by an empirical formulation. TIBL development was generally complex and irregular within the first few kilometres of the shore, while further inland more regular TIBL formation enabled the relatively accurate observation and prediction of TIBL height. DA - 1988 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1988 T1 - Growth, Structure and Prediction of the Thermal Internal Boundary Layer TI - Growth, Structure and Prediction of the Thermal Internal Boundary Layer UR - http://hdl.handle.net/11427/6920 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6920
dc.identifier.vancouvercitationComrie AC. Growth, Structure and Prediction of the Thermal Internal Boundary Layer. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1988 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6920en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Environmental and Geographical Scienceen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherEnvironmental and Geographical Scienceen_ZA
dc.titleGrowth, Structure and Prediction of the Thermal Internal Boundary Layeren_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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