Studies in ionospheric ray tracing
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
Some properties of magnetospheric electrons observed west of Sanae
- Authors: Greener, James G
- Date: 1973
- Subjects: Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5523 , http://hdl.handle.net/10962/d1012091 , Magnetosphere
- Description: The southern hemisphere has always been the neglected twin in the field ot geophysical research. The reasons for this are certainly not in the realm of science but in the history of man and his development in the northern half of the globe. Geophysically, however, our southern half provides a wealth of interesting problems and anomalies. Roederer (1966) explains the use of this word 'anomaly' by showing what some of the oddities of the southern hemisphere are, and by contrasting them with the corresponding regions of the earth across the equator. The principal feature is of course the geomagnetic surface field strength minimum at a point in the South Atlantic ocean very near the coast of Brazil. Intro., p. 1.
- Full Text:
- Date Issued: 1973
- Authors: Greener, James G
- Date: 1973
- Subjects: Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5523 , http://hdl.handle.net/10962/d1012091 , Magnetosphere
- Description: The southern hemisphere has always been the neglected twin in the field ot geophysical research. The reasons for this are certainly not in the realm of science but in the history of man and his development in the northern half of the globe. Geophysically, however, our southern half provides a wealth of interesting problems and anomalies. Roederer (1966) explains the use of this word 'anomaly' by showing what some of the oddities of the southern hemisphere are, and by contrasting them with the corresponding regions of the earth across the equator. The principal feature is of course the geomagnetic surface field strength minimum at a point in the South Atlantic ocean very near the coast of Brazil. Intro., p. 1.
- Full Text:
- Date Issued: 1973
Some ionospheric effects observed at sunrise
- Authors: Baker, D C
- Date: 1964
- Subjects: Sun -- Rising and setting , Ionosphere -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5513 , http://hdl.handle.net/10962/d1009496 , Sun -- Rising and setting , Ionosphere -- Research
- Description: The study of the ionosphere over the sunrise period is necessary for an understanding of the vtiriations in layer structure with time and has been a topic of research of many workers. On the whole these investigations have been restricted to a study of critical frequency variations with relatively short intervals of a few minutes between successive records, of N-h curves deduced from ionograms with long intervals (15 minutes or so) between successive N-h curves or of continuously monitored single frequency reflections. Not one of the three techniques is entirely satisfactory for a detailed study of ionospheric behaviour over sunrise. The first two do not give a sufficiently clear indication of what happens in the initial stages of layer development, while from the third incomplete data is obtained as to what is happening at a specific electron-density level. For this reason a preliminary investigation of the ionosphere over sunrise was made at Rhodes University during August, 1959. The records were obtained at four-and-a-half minute intervals and scaled by the method of KELSO (1952 ). "Many of t he results were inconclusive but it appeared that records would have to be taken at approximately one minute intervals and reduced to N-h curves by a scaling technique which made full allowance for low-level ionization if useful results were to be obtained. An attempt has been made in this thesis to investigate the behaviour of the ionosphere over sunrise more fully than can be done by the three techniques referred to. A number of observed phenomena are also examined. Part I deals with the theoretical background to ionosphere physics in general and describes the equipment, equipment modifications and experimental procedure. Part II presents the results obtained. The records for a largescale travelling disturbance are analysed. Various observed phenomena are described and discussed. A simple method of obtaining production rates from experimental data is described. The implications of the observed variations of production rates with height and time are discussed. Suggestions for further research and improvement of the methods used arc made in Charter 9.
- Full Text:
- Date Issued: 1964
- Authors: Baker, D C
- Date: 1964
- Subjects: Sun -- Rising and setting , Ionosphere -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5513 , http://hdl.handle.net/10962/d1009496 , Sun -- Rising and setting , Ionosphere -- Research
- Description: The study of the ionosphere over the sunrise period is necessary for an understanding of the vtiriations in layer structure with time and has been a topic of research of many workers. On the whole these investigations have been restricted to a study of critical frequency variations with relatively short intervals of a few minutes between successive records, of N-h curves deduced from ionograms with long intervals (15 minutes or so) between successive N-h curves or of continuously monitored single frequency reflections. Not one of the three techniques is entirely satisfactory for a detailed study of ionospheric behaviour over sunrise. The first two do not give a sufficiently clear indication of what happens in the initial stages of layer development, while from the third incomplete data is obtained as to what is happening at a specific electron-density level. For this reason a preliminary investigation of the ionosphere over sunrise was made at Rhodes University during August, 1959. The records were obtained at four-and-a-half minute intervals and scaled by the method of KELSO (1952 ). "Many of t he results were inconclusive but it appeared that records would have to be taken at approximately one minute intervals and reduced to N-h curves by a scaling technique which made full allowance for low-level ionization if useful results were to be obtained. An attempt has been made in this thesis to investigate the behaviour of the ionosphere over sunrise more fully than can be done by the three techniques referred to. A number of observed phenomena are also examined. Part I deals with the theoretical background to ionosphere physics in general and describes the equipment, equipment modifications and experimental procedure. Part II presents the results obtained. The records for a largescale travelling disturbance are analysed. Various observed phenomena are described and discussed. A simple method of obtaining production rates from experimental data is described. The implications of the observed variations of production rates with height and time are discussed. Suggestions for further research and improvement of the methods used arc made in Charter 9.
- Full Text:
- Date Issued: 1964
A study of the fluorescence excitation spectrum of crystalline anthracene
- Authors: Driver, Adrian Stanford
- Date: 1960
- Subjects: Fluorimetry , Anthracene crystals -- Spectra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5518 , http://hdl.handle.net/10962/d1011463 , Fluorimetry , Anthracene crystals -- Spectra
- Description: The work described in this thesis was performed at the Physics Department, Rhodes University during 1958 and 1959 under the supervision of Professor J.A. Gledhill. Use was made of a vacuum ultra-violet spectrograph which had been constructed in the Physics Department (1.1) and modifications to be described were made to this instrument. The instrument was used for studying the effects of oxygen on the fluorescence excitation spectrum of Anthracene.
- Full Text:
- Date Issued: 1960
- Authors: Driver, Adrian Stanford
- Date: 1960
- Subjects: Fluorimetry , Anthracene crystals -- Spectra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5518 , http://hdl.handle.net/10962/d1011463 , Fluorimetry , Anthracene crystals -- Spectra
- Description: The work described in this thesis was performed at the Physics Department, Rhodes University during 1958 and 1959 under the supervision of Professor J.A. Gledhill. Use was made of a vacuum ultra-violet spectrograph which had been constructed in the Physics Department (1.1) and modifications to be described were made to this instrument. The instrument was used for studying the effects of oxygen on the fluorescence excitation spectrum of Anthracene.
- Full Text:
- Date Issued: 1960
The photo-fluorescence properties of some organic materials
- Authors: Cameron, Antony John Wesley
- Date: 1959
- Subjects: Hydrocarbons -- Spectra -- Fluorescence , Organic compounds , Energy transfer
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5514 , http://hdl.handle.net/10962/d1010041 , Hydrocarbons -- Spectra -- Fluorescence , Organic compounds , Energy transfer
- Description: In this thesis I have given an account of the experimental work carried out by me at Rhodes University from the beginning of 1954 to the end of 1955, and the analysis of the results which was completed during the following two years, 1956 and 1957. The dissertation is divided into two sections; Part I deals with the photo fluorescence spectra of a large group of organic compounds, and Part 2 describes an investigation of the photo-fluorescence properties of and energy transfer in liquid organic solutions.
- Full Text:
- Date Issued: 1959
- Authors: Cameron, Antony John Wesley
- Date: 1959
- Subjects: Hydrocarbons -- Spectra -- Fluorescence , Organic compounds , Energy transfer
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5514 , http://hdl.handle.net/10962/d1010041 , Hydrocarbons -- Spectra -- Fluorescence , Organic compounds , Energy transfer
- Description: In this thesis I have given an account of the experimental work carried out by me at Rhodes University from the beginning of 1954 to the end of 1955, and the analysis of the results which was completed during the following two years, 1956 and 1957. The dissertation is divided into two sections; Part I deals with the photo fluorescence spectra of a large group of organic compounds, and Part 2 describes an investigation of the photo-fluorescence properties of and energy transfer in liquid organic solutions.
- Full Text:
- Date Issued: 1959