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Communication Dans Un Congrès Année : 2006

The Madden-Julian Oscillation (MJO) impacts on Southern African summer rainfall and Tropical-Temperate Interactions

Résumé

Composite maps of outgoing longwave radiation (OLR) anomalies over the Madden–Julian oscillation (MJO) cycle show marked intraseasonal fluctuations over southern Africa (south of 15°S). Large-scale convective clusters are seen to propagate eastward and then northward over the continent, mainly between 10° and 20°S. The corresponding response of the rainfall field presents the alternation, over the cycle, of dry and humid phases, which are both significant. Moisture flux anomalies indicate an intraseasonal modulation of the midtropospheric easterly flow over the Congo basin at 700 hPa; these fluctuations are coupled to meridional flux anomalies that extend from the tropical to the subtropical austral latitudes, and favor occurrences of wet or dry conditions over the domain. Though statistically significant, the influence of the MJO on southern Africa is however not homogeneous spatially, and only the tropical areas exhibit sharp periodicities in the 30–60-day period range.
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Dates et versions

hal-00269160 , version 1 (07-04-2008)

Identifiants

  • HAL Id : hal-00269160 , version 1

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Benjamin Pohl, Nicolas Fauchereau, Yves Richard, Mathieu Rouault. The Madden-Julian Oscillation (MJO) impacts on Southern African summer rainfall and Tropical-Temperate Interactions. South African Society for Atmospheric Sciences, Oct 2006, Bloemfontein, South Africa. ⟨hal-00269160⟩
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