The dynamics of cut-off lows and their vertical extension to the surface

dc.contributor.advisorNdarana, Thando
dc.contributor.coadvisorLandman, Willem Adolf
dc.contributor.emailweathermanbarnes@gmail.comen_ZA
dc.contributor.postgraduateBarnes, Michael A.
dc.date.accessioned2021-07-15T08:24:54Z
dc.date.available2021-07-15T08:24:54Z
dc.date.created2021
dc.date.issued2021
dc.descriptionThesis (PhD (Meteorology))--Universty of Pretoria, 2021.en_ZA
dc.description.abstractCut-off low (COL) pressure systems are critical weather systems which can result in resulting various severe weather events on South Africa. COLs are often associated with surface cyclones which can enhance weather-related impacts on affected communities. This is shown by a case study of Cape Storm, a COL extension associated with explosive cyclogenesis that had dire effects on the Western Cape of South Africa. The stratospheric effects that determine a COLs extension to the surface and eventual impact on South Africa are studied from a potential vorticity (PV) perspective in terms of a case study, a climatology and an idealised framework. Deep COLs (which extend to the surface) are most frequent in the autumn months, are longer lasting, are more mobile and found most frequently in the higher latitudes. Stratospheric, high-PV intrusions that are associated with COLs are studied in detail with respect to a COLs extension. PV intrusions which extend closer to the surface more frequently result in surface cyclogenesis. This is independent on the size (or intensity) of the intrusion as PV intrusions which extend from higher tropopause heights tend to result in shallow COL development. COLs, have in the past, been viewed as upper-level systems that systematically extend to the surface. Composite analysis however shows that deep COLs associated with deep PV intrusions result in the simultaneous amplification of troughs throughout the troposphere, with the surface cyclone developing within a day of the COL.en_ZA
dc.description.availabilityRestricteden_ZA
dc.description.degreePhD (Meteorology)en_ZA
dc.description.departmentGeography, Geoinformatics and Meteorologyen_ZA
dc.identifier.citationBarnes, MA 2021, The dynamics of cut-off lows and their vertical extension to the surface, PhD (Meteorology) Thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/80842>en_ZA
dc.identifier.otherS2021en_ZA
dc.identifier.urihttp://hdl.handle.net/2263/80842
dc.language.isoenen_ZA
dc.publisherUniversity of Pretoria
dc.rights© 2019 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.
dc.subjectUCTDen_ZA
dc.subjectMeteorologyen_ZA
dc.titleThe dynamics of cut-off lows and their vertical extension to the surfaceen_ZA
dc.typeThesisen_ZA

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