Decadal variability of summer Southern African rainfall

Bastien Dieppois, B. Pohl, M. Rouault, M. New, N. Keenlyside, Damian Lawler

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    Summer Southern African rainfall exhibit three significant timescales of variability over the 20th century: interdecadal (15–28 year), quasi-decadal (8–13 year) and interannual (2–8 year). Teleconnections with global sea-surface temperature and atmospheric circulation anomalies are different for each timescale. Interdecadal fluctuations in summer rainfallI are associated with the Pacific Decadal Oscillation (PDO), while quasi-decadal and interannual fluctuations are related to decadal ENSO-like, often described as the Interdecadal Pacific Oscillation (IPO), and ENSO. Annular geopotential anomalies related the Pacific SST influence strongly interact with those driven by the Southern Annular Mode (SAM). Shifts in the westerlies thus lead to anomalous low-level easterly moisture fluxes from the Mascarene region even though decadal timescales, which are not significantly expressed in the SAM.
    Original languageEnglish
    Title of host publicationSASAS 2015
    Subtitle of host publicationApplying the weather
    PublisherSouth African Society for Atmospheric Sciences
    Publication statusPublished - 2015
    EventSASAS 2015: Applying the Weather - Pretoria, South Africa
    Duration: 21 Sept 201522 Sept 2015
    Conference number: 31


    ConferenceSASAS 2015
    Country/TerritorySouth Africa


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