Change in the association between Indian Ocean sea-surface temperatures and summer rainfall over South Africa and Namibia

Landman, Willem A.; Mason, Simon J.

doi:10.1002/(sici)1097-0088(19991115)19:13<1477::aid-joc432>3.0.co;2-w

Cited by 72 publications

(65 citation statements)

References 43 publications

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“…This indicates that the climate shift has been pivotal in the reversal of the relationships, but this observation is not unique. Landman and Mason (1999) also observed that the warmer SSTs in the western (IO) (positive IODZM ) were associated with drier conditions of southern Africa prior to the late 1970s (climate shift) whereas the warmer SST anomalies during the post-shift period were associated with less intense deficits. Therefore, this finding may suggest that a preseason forecast of a very strong IODZM event does not necessarily translate into a very intense drought since, of late, the two seem to be inversely related.…”

Section: The Contribution Of Co-occurrence Years To the Relationshipmentioning

confidence: 94%

“…Glantz et al (1991); Landman and Mason (1999); Fauchereau et al (2003); Mulenga et al (2003); Reason and Jagadheesha (2005) suggest that ENSO falls short of accounting completely for the sub-regional rainfall variability. ENSO remote forcing of southern African rainfall is now recognized as not always being present and that, for sustained periods in the observed record, regional forcing has been much more important (Landman and Mason, 1999;Fauchereau et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: The Contribution Of Co-occurrence Years To the Relationshipmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Manatsa

Chingombe

Matarira

2008

Intl Journal of Climatology

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“…It should be noted that likelihood ratio tests are known to be more powerful than any other procedure for detecting weak signals (Chandler and Bate, 2007), so the failure to find significant ENSO relationships in this case study is not thought to be due to methodological limitations. Many investigators point to the weakening ENSO-Africa teleconnections in recent years (Landman and Mason, 1999;Sewell and Landman, 2001), and some authors have suggested that they should not be used as rainfall predictors particularly for downscaling purposes (Hewitson and Crane, 2006).…”

Section: Spatial and Temporal Predictorsmentioning

confidence: 99%

Stochastic simulation of rainfall in the semi‐arid Limpopo basin, Botswana

Kenabatho

McIntyre

Chandler

et al. 2011

Intl Journal of Climatology

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ABSTRACT:The application of spatial-temporal stochastic rainfall models to semi-arid or arid areas is expected to be particularly challenging because of the high variability of rainfall, sparse rain gauge networks with significant periods of missing rainfall and potential data quality issues. In this article, a generalized linear model (GLM) has been fitted to daily rainfall data from the period 1975-1999 for 13 gauges in a 7660 km 2 sub-basin of the Limpopo basin in Botswana, with the objective of exploring applicability of the GLM for infilling historic records and for climate change analysis. Several relevant statistics of rainfall space-time variability were used to analyse model performance, including use of an independent validation period and sites that were not used in the fitting. The GLM was considered to simulate rainfall adequately for the purpose of sub-basin-scale water resource studies, although the model uncertainty is high. The main factors affecting rainfall space-time variability were found to be seasonality, autocorrelation of daily rainfall, altitude, latitude and longitude. Addition of large-scale drivers of rainfall (pressure, humidity and temperature) further improved representation of inter-annual variability, and this link to large-scale climate potentially facilitates downscaling of global climate model outputs. Although the model was locally sensitive to data quality issues, there was no evidence that these issues affected sub-basin scale analysis.

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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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Change in the association between Indian Ocean sea-surface temperatures and summer rainfall over South Africa and Namibia

Cited by 72 publications

References 43 publications

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Stochastic simulation of rainfall in the semi‐arid Limpopo basin, Botswana

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

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