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Third-party-funded project

Recent circulation and rainfall variations in southern Africa

Project management at the University of Würzburg:

Participating scientists:

Based on satellite outgoing longwave radiation (OLR) data, anomaly patterns of Namibian summer rainfall (January to March) are identified by means of cluster analysis and characterized by anomalies of the upper horizontal wind field resulting from composite analy-sis of gridded wind components at the 200 hPa level (pentad time scale). The large-scale or-ganization of horizontal mass divergence (convergence) by upper anticyclonic outflow (cyc-lonic inflow) is linked with vertical uplift (subsidence) anomalies being responsible for the different spatial patterns of summer rainfall anomalies. In particular the upper easterly (west-erly) anomalies are linked to regions with wet (dry) conditions at the surface. Furthermore, patterns of sea surface temperature (SST) anomalies for the Atlantic and Indian Oceans have been derived by cluster analysis showing a close correspondence of patterns with prevailingly positive SST anomalies at lower latitudes in one of the oceans with below-average summer rainfall over widespread regions of southern Africa.

Key words:
    outgoing longwave radiation
    summer rainfall anomalies
    large-scale upper wind anomalies
    sea surface temperature anomalies

Projekt period: from 04.1996 to 03.1998

Funding institution:


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