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The estimation of precipitable water vapour from GPS measurements in South Africa
Includes bibliographical references (leaves 110-115).
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| Main Author: | |
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Division of Geomatics
2015
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| _version_ | 1867613278724685824 |
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| access_status_str | Open Access |
| author | Wonnacott, R T |
| author2 | Merry, Charles |
| author_browse | Merry, Charles Wonnacott, R T |
| author_facet | Merry, Charles Wonnacott, R T |
| author_sort | Wonnacott, R T |
| collection | Thesis |
| description | Includes bibliographical references (leaves 110-115). |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/14626 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:35.758Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Division of Geomatics |
| publisherStr | Division of Geomatics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/14626 The estimation of precipitable water vapour from GPS measurements in South Africa Wonnacott, R T Merry, Charles Global Positioning System Meteorology Includes bibliographical references (leaves 110-115). The propagation of the Global Positioning System (GPS) signal from the satellite to the receiver is affected by, among other factors, the atmosphere through which it passes and, whereas the affects of the ionosphere can be eliminated by the differencing of two transmitted frequencies, the affects of the troposphere remain one of the major sources of noise in traditional geodetic and positioning applications of GPS. This noise can, however, be turned into a signal for the meteorologist and, by applying suitable constraints and processing strategies, it is possible to estimate the amount of precipitable water vapour (PWV) in the atmosphere. The application of the GPS data for the estimation of PWV in the atmosphere is not a new concept and has been described in numerous publications and reports since the early 1990's (Bevis et al., 1992, Rocken et al., 1993). This project is, however, an attempt to test the technique using the South African network of permanent GPS base stations. This thesis sets out to answer four fundamental questions: i. In theory, can GPS observations be used to estimate the amount of precipitable water vapour (PWV) in the atmosphere? ii. What permanent GPS networks are being used in other countries around the world for similar applications and how successful are these applications? iii. Can data derived from the South African network of permanent GPS base stations, TrigNet, be used to estimate PWV with sufficient accuracy to be able to supplement the radiosonde upper air measurements of the South African Weather Service (SAWS)? iv. Is the estimation of PWV as derived from the GPS observations a true reflection of reality using the radiosonde ascent measurements and numerical weather model (NWM) data as a method of independent verification? The primary data sets used to estimate atmospheric PWV at hourly intervals for March 2004 were; i. GPS data derived from the South African network of permanent GPS base stations provided by the Chief Directorate of Surveys and Mapping (CDSM); and ii. Surface meteorological measurements supplied by the South African Weather Service (SAWS). The two independent data sets used to verify and test the technique were; i. Upper air measurements derived from radiosonde ascents provided by the SAWS. These measurements were used to compute Integrated Water Vapour (IWV) and then converted to PWV; and ii. PWV estimates derived from a Numerical Weather Model provided by the Department of Environmental and Geographical Sciences of UCT. By the comparing the estimates of PWV from the three techniques, viz. GPS, radiosonde and NWM, it was found that GPS will meet the accuracy requirements of the meteorologist and could be used to supplement radiosonde measurements for use in numerical weather models. 2015-11-04T10:28:19Z 2015-11-04T10:28:19Z 2005 Master Thesis Masters MSc http://hdl.handle.net/11427/14626 eng application/pdf Division of Geomatics Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Global Positioning System Meteorology Wonnacott, R T The estimation of precipitable water vapour from GPS measurements in South Africa |
| thesis_degree_str | Master's |
| title | The estimation of precipitable water vapour from GPS measurements in South Africa |
| title_full | The estimation of precipitable water vapour from GPS measurements in South Africa |
| title_fullStr | The estimation of precipitable water vapour from GPS measurements in South Africa |
| title_full_unstemmed | The estimation of precipitable water vapour from GPS measurements in South Africa |
| title_short | The estimation of precipitable water vapour from GPS measurements in South Africa |
| title_sort | estimation of precipitable water vapour from gps measurements in south africa |
| topic | Global Positioning System Meteorology |
| url | http://hdl.handle.net/11427/14626 |
| work_keys_str_mv | AT wonnacottrt theestimationofprecipitablewatervapourfromgpsmeasurementsinsouthafrica AT wonnacottrt estimationofprecipitablewatervapourfromgpsmeasurementsinsouthafrica |