Cut-off lows in the Southern Hemisphere and their extension to the surface

dc.contributor.authorBarnes, Michael A.
dc.contributor.authorNdarana, Thando
dc.contributor.authorLandman, Willem Adolf
dc.date.accessioned2022-08-25T10:01:03Z
dc.date.available2022-08-25T10:01:03Z
dc.date.issued2021-06
dc.description.abstractMany cut-off low (COL) climatologies have been done throughout the Southern Hemisphere. Few have focused on COL vertical depth and their link to surface cyclones that often accompany these systems. Here we extend these climatologies in order to gain an understanding of the spatial, mobility, temporal, and seasonal variability of COL extensions towards the surface. Deep COLs (dCOLs), with extension all the way to the surface, are most frequent in the autumn months, are longer lasting, are more mobile and found most frequently situated in the high latitudes. They are usually collocated with Rossby wave breaking (RWB) on multiple isentropic surfaces. These RWB events drive high potential vorticity air into the upper troposphere. The depths of these intrusions are also shown to be critical to the development of COL extensions with dCOLs associated with deeper intrusions into the mid-troposphere. Upper-level PV features are collocated with warm surface potential temperature anomalies which can play a critical role in surface cyclogenesis. The warm surface potential temperature features, when out of phase with coupled upper tropospheric processes (surface features lagging behind upper level processes), can inhibit surfaceward extension and result in shallow COL (sCOL) development. Composite analysis shows that dCOLs that drive their own surface low development result in the simultaneous amplification of troughs throughout the troposphere, with the surface cyclone developing within a day of the COL.en_US
dc.description.departmentGeography, Geoinformatics and Meteorologyen_US
dc.description.librarianhj2022en_US
dc.description.urihttp://link.springer.com/journal/382en_US
dc.identifier.citationBarnes, M.A., Ndarana, T. & Landman, W.A. Cut-off lows in the Southern Hemisphere and their extension to the surface. Clim Dyn 56, 3709–3732 (2021). https://doi.org/10.1007/s00382-021-05662-7.en_US
dc.identifier.issn0930-7575 (print)
dc.identifier.issn1432-0894 (online)
dc.identifier.other10.1007/s00382-021-05662-7
dc.identifier.urihttps://repository.up.ac.za/handle/2263/86956
dc.language.isoenen_US
dc.publisherSpringeren_US
dc.rights© The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature 2021. The original publication is available at : http://link.springer.comjournal/382.en_US
dc.subjectCut-off low (COL)en_US
dc.subjectCut-off low extensionsen_US
dc.subjectSurface cyclogenesisen_US
dc.subjectPotential vorticityen_US
dc.subjectRossby wave breaking (RWB)en_US
dc.subjectStratospheric intrusionsen_US
dc.titleCut-off lows in the Southern Hemisphere and their extension to the surfaceen_US
dc.typePostprint Articleen_US

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