Simulated Changes in Extreme Rainfall Over Southern Africa

Mason, Simon J.; Joubert, A. M.

doi:10.1002/(sici)1097-0088(19970315)17:3<291::aid-joc120>3.0.co;2-1

Cited by 64 publications

(24 citation statements)

References 22 publications

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“…At the same time, a decrease in the frequency of high rainfall totals throughout the region is simulated. Similar conclusions may not apply to the frequency of extreme daily rainfall events (Gordon et al, 1992;Yu and Nell, 1993;Mason and Joubert, 1995). It should be emphasised that these results are highly sensitive to even small differences in the expected changes in rainfall means and, most notably, variability (Katz and Brown, 1992).…”

Section: Implications For Flood and Drought Eventsmentioning

confidence: 82%

“…Despite the poor ability to model present day rainfall climatology within general circulation models, most of the general features of rainfall distribution and seasonality over southern Africa are modelled by the CSIRO 9-level with an acceptable accuracy (Joubert, 1995). Over the eastern half of South Africa, including the Lowveld, simulated annual rainfall totals and number of raindays are too high, but the respective spatial distributions are reproduced reasonably well (Mason and Joubert, 1995). Of concern, however, is a sensitivity of the model to sharp changes in topography that is particularly evident along parts of the east coast of the subcontinent.…”

Section: Rainfall Scenarios For the Lowveld For The Next Few Decades mentioning

confidence: 95%

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Climatic change over the Lowveld of South Africa

Mason

1996

Climatic Change

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There has been a 38% decrease in expected annual rainfall totals over the Lowveld, in the eastern part of South Africa, during the last two decades. The downward trend in mean annual rainfall is not replicated in the rest of the summer rainfall region above the escarpment. Rainfall variability over the Lowveld has been increasing since about the 1950s, although the increase in variability appears to have been slowing down in more recent years. Changes in the frequency and intensity of E1 Nifio/Southern Oscillation extreme events are only partly responsible for the observed desiccation and increase in rainfall variability. The CSIRO 9-level general circulation model simulates, for 2 x CO2 conditions, an insignificant decrease of 10% in the annual mean and a slight increase in the inter-annual variability of rainfall over the Lowveld. Other general circulation models likewise simulate only small changes in annual mean rainfall over the region. However, the simulated increase in rainfall variability by the CSIRO 9-level model is likely to be conservative since the model, being linked to a slab ocean, is unable to represent important features of ocean-atmosphere coupling in the region. Significant changes in the frequencies of extreme drought events and of heavy rains in the Lowveld are likely to occur even with only small changes in the rainfall climatology of the region.

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Section: Implications For Flood and Drought Eventsmentioning

confidence: 82%

Section: Rainfall Scenarios For the Lowveld For The Next Few Decades mentioning

confidence: 95%

Climatic change over the Lowveld of South Africa

Mason

1996

Climatic Change

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“…An increase in rainfall intensity is likely to have led to more highly erosive rainfall events and an increased frequency in the pulses of badland development. This has important implications for other semi-arid regions, where rates of erosion may increase as climate change increases the frequency of extreme rainfall events (Joubert et al, 1996;Mason and Joubert, 1997).…”

Section: Discussionmentioning

confidence: 99%

Evidence from field-based studies of rates of soil erosion on degraded land in the central Karoo, South Africa

Keay-Bright

Boardman

2009

Geomorphology

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The goal of the research is to develop components of the method aimed at output of information on reliefforming processes from archival and current remote sensing (RS) data with the use of the latest dataprocessing technologies, inclu ding photogrammetry and geoinformation systems (GIS). The proposed components of the methods are highly informative and economically effective. The object under study is located at the border of two active tectonic structures, the South Tatar arch and Melekesskian depression in the southeastern part of the East European platform (Fig. 1). Based on the study results, it is confirmed that neotectonic movements in the area under study and its recent geodynamical setting are directly related (Fig. 5). It is demonstrated that the morphometric method can be efficiently applied to predict zones of high geodynamic activity and to determine locations of such zones.

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“…Establishing the mechanisms that cause interannual variability in central southern African rainfall is not without difficulty, even for periods when instrumental precipitation data are available (cf. Mason and Joubert 1997;Nicholson 1997). Long-term patterns of rainfall variability have been attributed to a variety of causes, including oscillations in the luni-solar tide (Currie 1993) and variations in atmospheric standing wave 1 (Hurrell and van Loon 1994).…”

Section: Enso and Rainfall Variability In Central Southern Africamentioning

confidence: 99%

‘Splendid rains have fallen’: links between El Niño and rainfall variability in the Kalahari, 1840–1900

Nash

Endfield

2007

Climatic Change

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This study uses a range of published and unpublished historical documentary sources to explore the nature of rainfall variability in the Kalahari Desert and adjacent hardveld regions of central southern Africa during the seventeen Pacific El Niño-Southern Oscillation (ENSO) episodes that occurred between 1840 and 1900. Documentary data are used in two ways. First, maps of relative annual rainfall levels are presented for each of the 12 single-year and five protracted ENSO episodes during the period, in order to identify the associated inter-annual rainfall variations. These suggest that the relationship between ENSO episodes and rainfall variability identified for the twentieth century, whereby warm events are frequently preceded by wetter conditions during the austral summer prior to the event year and succeeded by drought in the following summer, has broadly held for much of the last 160 years. This is despite the long-term fluctuations in precipitation and temperature which are known to have occurred over this period. Droughts are identified following at least thirteen of the 17 single-year and protracted ENSO episodes. Pre-ENSO wetter periods are less common, with only nine of the ENSO episodes preceded by abovenormal rainfall. Second, the documentary data are analyzed in detail in order to reveal any evidence for high resolution intra-annual variations in the seasonal distribution of rainfall during ENSO events. Seasonal sequences of rainfall/drought appear to have closely followed contemporary patterns, with heavy rainfall commonly occurring late in the pre-ENSO year or early in the ENSO year(s), and drought at the start of the post-ENSO year. This relationship can be seen to hold most strongly for single-year ENSO warm events and for the first year of protracted events, but rainfall conditions were more variable during the later years of protracted events.

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Simulated Changes in Extreme Rainfall Over Southern Africa

Cited by 64 publications

References 22 publications

Climatic change over the Lowveld of South Africa

Climatic change over the Lowveld of South Africa

Evidence from field-based studies of rates of soil erosion on degraded land in the central Karoo, South Africa

‘Splendid rains have fallen’: links between El Niño and rainfall variability in the Kalahari, 1840–1900

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