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Mountain wave turbulence in the lee of the Hex River Mountains
Thesis (MSc)--Stellenbosch University, 2012.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867614093551075328 |
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| access_status_str | Open Access |
| author | Van der Mescht, Deon |
| author2 | Eloff, P. J. |
| author_browse | Eloff, P. J. Van der Mescht, Deon |
| author_facet | Eloff, P. J. Van der Mescht, Deon |
| author_sort | Van der Mescht, Deon |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2012. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/20240 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:33.531Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/20240 Mountain wave turbulence in the lee of the Hex River Mountains Van der Mescht, Deon Eloff, P. J. Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies. Atmospheric turbulence -- South Africa -- Hex River Mountains Maontain wave -- South Africa -- Hex River Mountains Weather ballloon soundings Y-component horizontal vorticity Dissertations -- Geography and environmental studies Theses -- Geography and environmental studies Geography and Environmental Studies Thesis (MSc)--Stellenbosch University, 2012. ENGLISH ABSTRACT: Despite recorded mountain wave related aircraft accidents in South Africa, very little literature exists on South African mountain waves. This study discusses the results of a mountain wave study in the Hex River Mountains in the Western Cape province of South Africa. The aim of this study was to measure mountain wave turbulence on the lee side of the mountains by conducting weather balloon soundings on the upwind and lee sides of the mountains. These soundings were performed over four days in the winter and spring, with each field day representing different synoptic scale weather conditions. Lee wave rotors were detected from several of the lee wave soundings. Significant values of horizontal vorticity around a north-south axis (y-component horizontal vorticity) were detected. The instrumentation was highly sensitive and able to measure even weak up and downdraft velocities associated with the rotors. Strong downdrafts were measured some mountain waves, but no strong downdrafts were detected near rotors which occurred below the mountain waves. The two dimensional positions of balloons were only available after a considerable amount of reanalysis. If this data can be made available onsite shortly after soundings, it can be used to decide where to move launch sites to, in order to obtain optimal results. AFRIKAANSE OPSOMMING: Ten spyte van gedokumenteerde berggolf-verwante vliegongelukke, bestaan baie min literatuur oor Suid Afrikaanse berggolwe. Hierdie tesis bespreek die resultate van ‘n berggolfstudie in die Hexrivier Berge in the Weskaap Provinsie van Suid- Afrika. Die doel van hierdie studie was om die berggolfturbulensie aan die lykant van die berge te meet deur middel van weerballonopstygings aan beide die winden lykante van die berge. Hierdie opstygings is oor ‘n tydperk van vier winter en lente dae uitgevoer, met elkeen van die dae wat verskillende sinoptiese weersomstandighede verteenwoordig het. Rotors is waargeneem in die data van verskeie ballonopstygings wat aan die lykant uitgevoer is. Beduidende waardes van horisontale vortisiteit rondom ‘n noord-suid as (y-komponent horisontale vortisiteit) is gemeet. Die instrumentasie was hoogs sensitief en kon selfs swak op- en afstrominge meet. Sterk afstrominge is waargeneem in berggolwe, maar nie in die omgewing van rotors wat onmder die berggolwe voorgekom het nie. Die twee-dimensionele posisies van ballonne was slegs na aansienlike heranaliese van die data beskikbaar. Indien hierdie data kort na opstygings beskikbaar is tydens veldwerk, kan dit help met besluite oor alternatiewe posisies waarvandaan ballonopstygings gedoen kan word ten einde optimale resultate te bekom. Masters 2012-03-15T10:56:21Z 2012-03-30T10:55:58Z 2012-03-15T10:56:21Z 2012-03-30T10:55:58Z 2012-03 Thesis http://hdl.handle.net/10019.1/20240 en_ZA Stellenbosch University 150 p. : ill., maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Atmospheric turbulence -- South Africa -- Hex River Mountains Maontain wave -- South Africa -- Hex River Mountains Weather ballloon soundings Y-component horizontal vorticity Dissertations -- Geography and environmental studies Theses -- Geography and environmental studies Geography and Environmental Studies Van der Mescht, Deon Mountain wave turbulence in the lee of the Hex River Mountains |
| title | Mountain wave turbulence in the lee of the Hex River Mountains |
| title_full | Mountain wave turbulence in the lee of the Hex River Mountains |
| title_fullStr | Mountain wave turbulence in the lee of the Hex River Mountains |
| title_full_unstemmed | Mountain wave turbulence in the lee of the Hex River Mountains |
| title_short | Mountain wave turbulence in the lee of the Hex River Mountains |
| title_sort | mountain wave turbulence in the lee of the hex river mountains |
| topic | Atmospheric turbulence -- South Africa -- Hex River Mountains Maontain wave -- South Africa -- Hex River Mountains Weather ballloon soundings Y-component horizontal vorticity Dissertations -- Geography and environmental studies Theses -- Geography and environmental studies Geography and Environmental Studies |
| url | http://hdl.handle.net/10019.1/20240 |
| work_keys_str_mv | AT vandermeschtdeon mountainwaveturbulenceintheleeofthehexrivermountains |