Thesis (Ph. D.)--University of Oulu, 1989. / This thesis is based on and accompanied by reprints of 6 original articles by the author of the thesis. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. Includes bibliographical references.

This study identifies the spatial and temporal change of three types of Urban Heat Island (UHI). The Surface Urban Heat Island (SUHI) and Canopy Urban Heat Island (CUHI) are common UHI phenomena; however, the Radiant Urban Heat Island (RUHI) is proposed as a new type of UHI. Surface temperature, air temperature, and mean radiant temperature are used as indicators to measure the SUHI, CUHI, and RUHI respectively. Visual, statistical and microclimate approaches are carried out to increase the spatial and temporal resolution of the UHI modelling. The modelling approaches employ the integration of remote sensing, GIS, and ground measurements to improve the 2D and 3D representation of the UHI. Furthermore, the influencing parameters on the formation of the three types of UHI are investigated. The research aim is to produce an integrated approach that improves the low spatial or temporal coverage of UHI models in the literature. Moreover, it quantifies the causative parameters on the formation of UHI, and proposes mitigation strategies accordingly. London, Baghdad and Birmingham are the study areas of the SUHI, to test the variability of the size, population, Land Use/Cover (LULC), geometry, microclimate, geography, and level of development. Birmingham is chosen to study the CUHI and RUHI, because of the availability of the required data to model these UHIs. The SUHI is carried out between (2000- 2015) by the Land Surface Temperature (LST) of the thermal bands of Landsat, ASTER, MODIS and other auxiliary data. The CUHI, on the hand, is undertaken for two years (June 2012- June 2014) using high density air temperature measurements (HiTemp data), and the RUHI is simulated based on the mean radiant temperature (Tmrt) for four seasonal days that are part of the HiTemp. The integrated approach of the research employs three indictors (LST, air temperature, and Tmrt) to model the UHI which is unprecedented in the literature. Furthermore, within the use of each indicator there is a novel approach. The LST is acquired for three different cities using thermal bands from 1 m to 1000 m spatial resolution by employing diverse satellite and airborne images for about 15 years. The air temperature is hourly measured for two years by over 100 ground stations to produce high spatial and temporal thermal maps, and some of the ground stations are used to simulate the Tmrt. The Tmrt is used for the first time to model the UHI as a new indictor, which upgrades the 2D UHI using LST and air temperature to 3D UHI simulation. The influencing parameters on the formation of three types of UHI derived from the three indicators are identified, and they include many potential factors not investigated together in the literature. The findings of such topic might be useful for decision-makers when building new cities or modifying the existing ones, even the public can know more about their environment. The results show that, London and Birmingham core area usually work as SUHI during the day and night-time. However, Baghdad city exhibits low LST in the daytime except for high density residential area as well as indusial and commercial units. Similarly, Baghdad city becomes a SUHI in the night-time, and the water bodies have high LST during the cold nights for the three cities. Despite the higher diurnal, daytime and night-time LST of Baghdad compared to London and Birmingham, the London SUHI intensities were higher than those of Baghdad. The temporal change of the average LST and SUHI for Birmingham did not show significant change over the study period just like London; however, they both gave high spatial variability. The diurnal averages of SUHI are 9.41, 11.29, and 7.63 ºC for Baghdad, London, and Birmingham (during 2003-2015) respectively. The CUHI appear daytime and night-time in Birmingham urban and suburban areas throughout the different seasons for 56% of the total hours of two years, to reach 13.53 ºC. The simulation of Tmrt show the presence of daytime Radiant Urban Cool Island (RUCI) in the City Centre of Birmingham, while, the night-time induced the development of RUHI. Various influencing parameters contribute to the different types of UHI. The land cover types and anthropogenic heat are the main contributors to the SUHI. Fourteen controllable and uncontrollable predictors control the CUHI development. On the other hand, the radiation fluxes and shadow patterns direct the RUHI formation. Overall, the spatial and temporal behaviour of UHI varies for the different types of UHI. Each type of UHI is controlled by a set of causative parameters, and these might differ based on the type of UHI as well as where and when it occurs.

A finite difference algorithm for solving the forward modelling problem of geo-electromagnetic induction in three-dimensional structures has been developed in this thesis. Novel features of the method include the incorporation of a thin sheet of anomalous conductance at the surface of an otherwise quite general three-dimensional structure in which the anomalous region is allowed to approach two-dimensional configurations at infinity; the use of magnetic rather than the electric field components for obtaining the solution; the use of integral boundary conditions at the top and bottom of the model; and the application of new cell-integral finite difference equations to the main body of the model. The algorithm has been tested for synthetic models against results delivered by existing two and three dimensional modelling programs which are already well established. The results are found to be very satisfactory. Applications of the algorithm have been shown for two cases. First, the dependence of the induction vectors on the period ranging from 10 to 10000 s has been studied for a model with two perpendicular lateral conductivity contrasts; the directions of induction vectors vary from site to site reflecting the combined effect of the two perpendicular contrasts. In the second case, the distortion effect due to small surface inhomogeneities over a buried 2D anomaly was studied using induction vectors and difference vectors. There is evidence of mutual coupling in a certain region which invalidates a simple subtraction of the vectors to reveal the form of the buried anomaly, but elsewhere the procedure appears to be quite valid. Since surface anomalies can be simulated by an anomalous thin sheet over the general 3D structure, it is suggested that this algorithm could be very useful for testing the validity of existing schemes for impedance tensor decompositions used in MT studies when surface anomalies are thought to be distorting the real data. / Graduate

Maps in pocket.

This thesis deals with both mathematical and analogue models for studying electromagnetic variations at the earth's surface. The field components are studied for frequencies in the range 10ˉ⁴ to 10³ cycles/sec and for earth conductivities in the range 10ˉ¹⁶ to 10ˉ¹º emu. Expressions are developed for the electric and magnetic field components at the surface and within the upper layer of a horizontally stratified flat conducting earth in the field of incident plane waves. Extensive results of amplitudes and phase angles are obtained for various frequencies, angles of incidence, layer thicknesses, depths, and conductivities. As an extension of this problem, expressions for a multilayer earth (n layers) are developed and evaluated. Each of several thick layers is divided into a sufficient number of sublayers, with changing conductivity, to represent to a good approximation a continuous change in conductivity. The conductivity distributions used are of interest in geophysics. The results for the plane wave model indicate that the amplitudes and phase angles are strongly affected by the conductivity structure. The electric and magnetic fields at the surface of a flat homogeneous conducting earth in the near field of an oscillating line current are studied. The equations for the amplitudes and phase angles developed by Law and Fannin (1961) are used for the calculations. Extensive results of amplitudes and phase angles are obtained for various frequencies, conductivities, source heights, and locations with respect to the overhead current. The results indicate that the vertical to horizontal magnetic field ratios are in the range of experimentally observed values. An analogue model suitable for studying the behavior of the natural geomagnetic and telluric field variations for various geological structures was constructed. The two types of field sources used were an oscillating sheet current and an oscillating line current. Extensive measurements of amplitudes and phase angles for the horizontal electric, the horizontal magnetic, and the vertical magnetic field components are obtained and discussed for various geological structures including a flat layered earth, cylindrical bodies embedded in the surface layer, vertical faults and dykes, sea mounts and conducting domes, coastline structures (sea-land interface and an upwelling in a high-conductivity zone within the mantle), and islands in an ocean channel. The results obtained for the coastline structures and islands in an ocean channel tend to support the proposed structures suggested by various workers (Schmucker 1964, Lambert and Caner 1965, Lokken and Maclure 1966) in describing the experimentally observed coastal magnetic field anomalies. The analogue model constructed and used for this work readily lends itself to studying a wide range of geological structures for a variety of source fields in addition to the ones used here. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Dynamic spectra processed from data recorded on magnetic tape at the mid-latitude Ralston station (Alberta) in 1967 have been studied in detail. The Pc3,4 pulsations appear to behave in a much more complicated manner than reported by other observers at low-latitude stations. The variation of the Pc3,4 frequency at Ralston assumes different forms from one day to another, the pattern depending largely upon the general level of magnetic disturbance represented by the K(p)-index. It appears, however, that most of the Pc3,4 spectra analysed may be classified into one of, or a combination of, four well-defined diurnal patterns under steady magnetospheric conditions. An interpretation is offered to explain the existence as well as the fine structure of these four diurnal patterns. The crux of the present interpretation is that Ralston, under moderate magnetospheric agitation, may pick up micropulsation activities originating from the plasmasphere and/or the plasmatrough depending upon its position relative to the plasmapause. Eigen oscillations of modified Alfven mode (poloidal oscillation) in these two magnetospheric regions are considered to be the prime sources of the ground observed Pc3,4 magnetic pulsations. Such suggestion is reinforced by observations made simultaneously at other mid- and high-latitude stations. Other morphological properties of Pc3 and Pc4 are discussed in the light of the new interpretation. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A brief summary of observational data is presented, covering the disturbances recorded within seconds of high-altitude nuclear detonations, with particular emphasis on the "phase B" signal recorded at H+2 seconds following the "Starfish" test of July 9, 1962. The salient characteristics of this signal are specified, and a number of suggested models are analysed in detail. Although no conclusive decision can be reached on the basis of presently available data, the most likely mechanism appears to be hydromagnetic waves along the field line through the detonation point, with energy conversion into electromagnetic modes at the mirror points. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Call number: LD2668 .T4 1964 D74 / Master of Science

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