Climatic variability and change over southern Africa: a reflection on underlying processes

Mason, Simon J.; Jury, Mark R.

doi:10.1177/030913339702100103

Cited by 217 publications

(212 citation statements)

References 138 publications

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“…It has been observed in regional streamflow (Abbott and Dyer, 1976;Partridge, 1985;Alexander, 1995), as well as in the temperature record (Keen, 1971) and in tree-ring data (Visagie, 1985;Tyson, 1986). Multi-decadal variability in the 16-20-year band has also been observed in ocean temperatures around South Africa (Mason, 1990;Mason and Jury, 1997) and appears to be similar to ∼21-year variability reported in Southern Hemisphere sea surface temperatures (Folland et al, 1984). It is present in historical joint Northern Hemisphere surface air temperature and sea-level pressure (Mann and Park, 1996) and in joint empirical orthogonal function analysis of global historical sea surface temperatures and mean sea-level pressures (Allan, 2000).…”

Section: Variability Over the Period Of Meteorological Recordsupporting

confidence: 59%

Millennial to multi‐decadal variability in the climate of southern Africa

Tyson

Cooper

McCarthy

2002

Intl Journal of Climatology

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Wavelet analysis has been used to determine changes in the variability of southern Africa climate over the last three millennia. The structure of the variability in a 3000-year δ 18 O record has been compared with that in tree ring data for the last 600 years and both to the variability in annual rainfall and runoff during the 20th century. Preferred modes of variability are shown to have occurred in all the data sets. For overlap periods, the variability modes are in phase where the data are for a common seasonal rainfall regime.From the combined proxy and instrumental data it appears that an ∼1500-year oscillation in rainfall variability may have been present during the late Holocene. Considerable variability in South African climate has been shown to reside in the bands 500-800 and 60-120 years. The latter is manifest in stable isotope and tree ring proxy data and in measured rainfall and runoff, and shows a distinctive latitudinal variation over southern Africa. The ∼80-year variability has been present for at least 600 years in the tree ring data and at least 3000 years in the stable isotope data. During the 20th century, the variability in the 60-120-year range was confined south of 20°S in southern Africa.The existence of considerable multi-decadal climate variability in the range 16-20 years has been confirmed south of 15°S. Tree ring data show that the ∼18-year oscillation in climate has been present for at least 600 years. The 500-800-year, ∼80-year and ∼18-year variability has been both frequency-and amplitude-modulated over time, but never to the extent that the variability bands have lost their integrity. Their persistence is a striking feature of southern African climate.The millennial, centennial and multi-decadal variability in climate over southern Africa finds counterparts with temporal variability in similar time ranges reported elsewhere. Spatial teleconnections in variability likewise have been shown to occur. The changes in climate variability over the subcontinent are part of variability changes affecting the Earth system in many other regions.

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Section: Variability Over the Period Of Meteorological Recordsupporting

confidence: 59%

Millennial to multi‐decadal variability in the climate of southern Africa

Tyson

Cooper

McCarthy

2002

Intl Journal of Climatology

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“…Saji and Yamagata (2003) have used partial correlation analysis to show that the positive IODZM events, rather than El Niño, dominate the enhancement of east African rainfall. At the same time, other studies (Mason and Jury, 1997;Jury et al, 2002;Fauchereau et al, 2003) concluded that east Africa shares a maritime rainfall regime with the west IO, while convection over southern Africa is inversely related. This observation links the southern African rainfall regime to the IODZM.…”

Section: Introductionmentioning

confidence: 86%

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Manatsa

Chingombe

Matarira

2008

Intl Journal of Climatology

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A comparative study of the impact of the anomalous positive Indian Ocean SST gradient, referred to as the Indian Ocean Dipole/Zonal Mode (IODZM), and El Niño-Southern Oscillation (ENSO) on Zimbabwe seasonal rainfall variability for the period 1940-1999, is documented. Composite techniques together with simple and partial correlation analyses are employed to segregate the unique association related to IODZM/ENSO with respect to the Zimbabwe seasonal rainfall.The analysis reveals that the IODZM impact on the country's summer rainfall is overwhelming as compared to that of ENSO when the two are in competition. The IODZM influence remains high (significant above 99% confidence level), even after the influence of ENSO has been removed, while that of ENSO collapses to insignificance (even at 90% confidence level) when the IODZM contribution is eliminated. The relationship between ENSO and Zimbabwe seasonal rainfall seems to be sustained through El Niño occurring in the presence of positive IODZM events. However, when the co-occurring positive IODZM and El Niño events are removed from the analysis, it is apparently clear that ENSO has little to do with the country's rainfall variability. On the other hand, positive IODZM is mostly associated with the rainfall deficits, whether or not it co-occurs with El Niño. However, the co-occurrence of the two events does not necessarily suggest that El Niño influences droughts through the positive IODZM events. The El Niño event components during co-occurrence seem to be unrelated (at least linearly) to the droughts, while the positive IODZM events display a relatively strong relationship that is significant above the 95% confidence level. It thus becomes important to extend the study of this nature to cover the whole of southern Africa, so that the extent of the impact of the phenomena can be realized over the whole region.

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“…Tyson et al, 1975;Taljaard, 1986;Walker, 1990;Lindesay and Jury, 1991;Matarira and Jury, 1992;Levey and Jury, 1996;Mason and Jury, 1997;Landman and Mason, 1999;Reason and Mulenga, 1999;Cook et al, 2004). Since many countries in the region have a large rural population and tend to rely on rain-fed agriculture, southern Africa is vulnerable to the impacts of rainfall variability, posing challenges for food security and planning (Vogel and O'Brien, 2003).…”

Section: Introductionmentioning

confidence: 99%

Interannual variability in rainy season characteristics over the Limpopo region of southern Africa

Reason

Hachigonta

Phaladi³

2005

Int. J. Climatol.

110

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This study focuses on the interannual variability of dry spell frequencies, dry and wet spell characteristics and onset dates of the austral summer rainy season over the Limpopo region (22-25°S, 27-32°E) of northern South Africa. These characteristics of the rainy season are of considerable interest to farmers, water resource managers and other user groups. The Limpopo region supports a large rural population dependent on rain-fed agriculture as well as significant biodiversity, particularly in the Kruger National/Limpopo Transfrontier Park. It is also a region prone to devastating floods and droughts. Evidence is presented that summer dry spell frequency and onset date are related to ENSO via changes in regional circulation. Niño 3.4 sea surface temperature (SST) anomalies appear to show a robust relationship with dry spell frequency during the 1979-2002 period analysed. Anomalies in onset date of the rainy season during 1979-2002 appear to be inversely related to Niño 3.4 SST, with the relationship strengthening after 1986. These results suggest that there may be some predictability in these parameters, particularly in dry spell frequency during austral summer, based on existing skill in predicting tropical Pacific SST.

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Climatic variability and change over southern Africa: a reflection on underlying processes

Cited by 217 publications

References 138 publications

Millennial to multi‐decadal variability in the climate of southern Africa

Millennial to multi‐decadal variability in the climate of southern Africa

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Interannual variability in rainy season characteristics over the Limpopo region of southern Africa

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