Attributes of cut-off low induced rainfall over the Eastern Cape Province of South Africa

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Authors

Molekwa, Samuel
Engelbrecht, Christina Johanna
Rautenbach, Cornelis Johannes de Wet

Journal Title

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Publisher

Springer

Abstract

Cut-off low (COL) weather systems that are associated with rainfall over the Eastern Cape are considered in this study. COLs are objectively identified and tracked over a 31-year period. Daily rainfall data of 22 evenly distributed stations over the Eastern Cape are utilized. Only COLs with a minimum spatial distribution, defined as more than a third of the rainfall stations that need to report rainfall on at least 1 day of a COL event, are considered for analysis of rainfall attributes. These attributes include the occurrence of COL rain days of different magnitudes, the distribution of the depth and temperature of the COL centres for the rain days of different magnitudes, the associated spatial distribution of rainfall as well as the associated atmospheric circulation. The frequency of COLs over the Eastern Cape has a winter maximum and a summer minimum. COL rain days of small, mediumand large magnitudes occur most frequently during the winter, while small- and medium-magnitude COL rain days experience peaks in autumn and spring, respectively. The low-level flow, and in particular the position of the low/trough, seems to be the determinant factor in the occurrence, magnitude and spatial extent of COL-induced rainfall.

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Keywords

Eastern Cape Province, South Africa, Minimum spatial distribution, Weather systems, Cut-off low (COL), Weather systems

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Citation

Molekwa, S, Engelbrecht, CJ & Rautenbach, CJD 2014, 'Attributes of cut-off low induced rainfall over the Eastern Cape Province of South Africa', Theoretical and Applied Climatology, vol. 118, no.1, pp. 307-318.