Browsing by Author "Tadross, M"

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    A model investigation of interannual winter rainfall variability over southwestern South Africa and associated ocean-atmosphere interaction
    (2003) Reason, C J C; Jagadheesha, D; Tadross, M
    We have investigated the variability of inter-annual winter rainfall over the southwestern Cape region of South Africa and associated large-scale atmosphere-ocean interaction upstream over the South Atlantic using the HadAM3 atmospheric general circulation model. This model was run for the period from 1990 to 1999 using mean monthly global sea-surface temperature (SST) as surface boundary condition over the global ocean. Diagnostics of winter (May to September) model output averaged over 1990-99 suggest that the HadAM3 model represents the general circulation in the South Atlantic / African sector reasonably well for this season at least. In addition, model years with wet and dry winters over the study area tended also to be those that were observed to be anomalously wet or dry. Wet minus dry season composite fields were used to investigate the model's inter-annual variability. The composite difference fields for low- and mid-level winds, sea-level pressure, and moisture flux all indicated wet winters being associated with increased inflow from tropical South America (originating in the equatorial western Atlantic at low levels) contributing relatively moist air to the westerly flow heading towards the southwestern Cape. A stronger jet over the South Atlantic promoted the passage of storms towards the Cape. Large areas of cyclonic vorticity anomalies, enhanced eddy activity, increased thickness in the lower atmosphere and low-level convergence near and upstream of the southwestern Cape in the model composite differences all favoured increased storm systems as well as their local intensification, implying enhanced rainfall. The results presented here suggest that the model can represent the interannual variability of winter rainfall over the study region and shed light on the mechanisms potentially associated with anomalously wet winters there.
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    Impacts, vulnerability and adaptation in key South African sectors: an input into the Long Term Mitigation Scenarios process.
    (Energy Research Centre, University of Cape Town, 2007) Midgley, G; Chapman, R; Mukheibir, P; Tadross, M; Hewitson, B; Wand, S; Schulze, R; Lumsden, T; Horan, M; Warburton, M; Kgope, B; Mantlana, B; Knowles, A; Abayomi, A; Ziervogel, G; Cullis, R; Theron, A
    Ten free-standing chapters make up this report, and this Executive Summary and supporting Synthesis Report serve to draw together the main findings in both an abbreviated and an extended and illustrated format that focuses on main findings, but also adds a level of detail for the purpose of communicating the key results, and the uncertainties associated with them, for the benefit of a policy maker. The chapters that make up this report are compiled as separate documents as follows. These are generally reviews of the literature available, but in some cases comprise new work that has been carried out to provide information in an area that is lacking an assessment.
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    A status quo, vulnerability and adaptation assessment of the physical and socio-economic effects of climate change in the Western Cape
    (2005) Midgley, G F; Chapman, R A; Hewitson, B; Johnston, P; de Wit, M; Ziervogel, G; Mukheibir, P; van Niekerk, L; Tadross, M; van Wilgen, B W; Kgope, B; Morant, P D; Theron, A; Scholes, R J; Forsyth, G G
    The South African Country Study on Climate Change, carried out in the late 1990’s, identified the Northern and Western Cape Provinces as being most at risk from projected climate change-induced warming and rainfall change (results of this study are summarized in South Africa’s initial National Communication, prepared in accordance with Article 12 of the United Nations Framework Convention on Climate Change: www.environment.gov.za/Documents/Documents/2005Feb22/NatCom_Nov%202003%20(b). doc ). However, this study was based on a limited set of model projections of climate change that have now been superseded by projections using more advanced techniques. In this study we have carried out a broad reassessment of the vulnerability of the Western Cape to climate change impacts, using a wider range of climate scenarios from more sophisticated climate models, and for a range of sectors (with the exception of agriculture and fisheries, according to our brief). We also identify some key adaptive strategies that might alleviate or avoid the worst impacts of climate change in some sectors. We conclude that further detailed study of some of the implications of these findings will be necessary to explore these and further strategies in order to guide policy development.