The influence of the lower stratosphere on ridging Atlantic Ocean anticyclones over South Africa

Show simple item record Ndarana, Thando Bopape, Mary-Jane Morongwa Waugh, Darryn Dyson, Liesl L. 2019-04-10T09:22:46Z 2018-08-01
dc.description.abstract The link between Rossby wave breaking and ridging Atlantic Ocean anticyclones in the South African domain is examined using NCEP–DOE AMIP-II reanalysis data. A simple composite analysis, which used the duration of ridging events as a basis of averaging, reveals that ridging anticyclones are coupled with Rossby wave breaking at levels higher than the dynamical tropopause. Lower-stratospheric PV anomalies extend to the surface, thus coupling the ridging highs with the lower stratosphere. The anomaly extending from the 70-hPa level to the surface contributes to a southward extension of the surface negative anomaly over the Namibian coast, which induces a cyclonic flow, causing the ridging anticyclone to take a bean-like shape. The surface positive anomaly induces the internal anticyclonic flow within the large-scale pressure system, causing the ridging end to break off and amalgamate with the Indian Ocean high pressure system. Lower-stratospheric Rossby wave breaking lasts for as long as the ridging process, suggesting that the former is critical to the longevity of the latter by maintaining and keeping the vertical coupling intact. en_ZA
dc.description.department Geography, Geoinformatics and Meteorology en_ZA
dc.description.embargo 2019-08-01
dc.description.librarian am2019 en_ZA
dc.description.sponsorship This research was partially funded by the Water Research Commission of South Africa. en_ZA
dc.description.uri en_ZA
dc.identifier.citation Ndarana, T., Bopape, M.-J., Waugh, D. et al. 2018, 'The influence of the lower stratosphere on ridging Atlantic Ocean anticyclones over South Africa', Journal of Climat, vol. 31, no. 15, pp. 6175-6187. en_ZA
dc.identifier.issn 0894-8755 (print)
dc.identifier.issn 1520-0442 (online)
dc.identifier.other 10.1175/JCLI-D-17-0832.1
dc.language.iso en en_ZA
dc.publisher American Meteorological Society en_ZA
dc.rights © 2018 American Meteorological Society en_ZA
dc.subject Ocean currents en_ZA
dc.subject Wave breaking en_ZA
dc.subject Vertical coupling en_ZA
dc.subject Stratospheric circulations en_ZA
dc.subject Lower stratosphere en_ZA
dc.subject High pressure system en_ZA
dc.subject Composite analysis en_ZA
dc.subject Anticyclonic flow en_ZA
dc.subject Anticyclones en_ZA
dc.subject Liquid waves en_ZA
dc.subject Atmospheric pressure en_ZA
dc.title The influence of the lower stratosphere on ridging Atlantic Ocean anticyclones over South Africa en_ZA
dc.type Article en_ZA

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