Wet and dry spells within particularly wet and dry summers in the South African summer rainfall region

Cook, Celia; Reason, C. J. C.; Hewitson, Bruce

doi:10.3354/cr026017

Cited by 174 publications

(150 citation statements)

References 18 publications

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“…9a, c, e;Cook et al 2004;Vigaud et al 2009). Negative geopotential height anomalies in the lower troposphere cover almost the whole southern African subcontinent.…”

Section: Large-scale Circulation Anomalies Related To the Above/belowmentioning

confidence: 99%

Dynamical seasonal prediction of Southern African summer precipitation

et al. 2013

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Prediction skills for southern African (16˚-33˚E, 22˚-35˚S) summer precipitation in the Scale Interaction Experiment-Frontier coupled model is assessed for the period of 1982-2008. Using three different observation datasets, deterministic forecasts are evaluated by anomaly correlation coefficients, whereas scores of relative operating characteristic and relative operating level are used to evaluate probabilistic forecasts. It is shown that these scores for forecasts of December-February precipitation initialized on October 1 st are significant at 95%confidence level. On a local scale, the prediction skills in the northwestern and central parts of southern Africa are higher than those in northeastern South Africa. El Niño/Southern Oscillation (ENSO) provides the major source of predictability, but the relationship with ENSO is over-confident in the model. Also, the Benguela Niño, the basin mode in the tropical Indian Ocean, the subtropical dipole modes in the South Atlantic and the southern IndianOceans and ENSO Modoki may provide additional sources of predictability. When prediction skills are evaluated for the whole wet season from October to the following April, it is found that precipitation anomalies in December-February are most predictable. The present study presents promising results for seasonal prediction of precipitation anomalies in the extratropics, where seasonal forecast are considered a difficult task.3

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“…9a, c, e;Cook et al 2004;Vigaud et al 2009). Negative geopotential height anomalies in the lower troposphere cover almost the whole southern African subcontinent.…”

Section: Large-scale Circulation Anomalies Related To the Above/belowmentioning

confidence: 99%

Dynamical seasonal prediction of Southern African summer precipitation

et al. 2013

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“…In this study, we consider the rainfall characteristics of the Limpopo region (22-25°S, 27-32°E) of northern South Africa, a region very prone to severe drought and flood events and by significant intraseasonal variability during the core rainy season (December-February) (Levey and Jury, 1996;Tennant and Hewitson, 2002;Cook et al, 2004). This region supports a relatively large and poverty-stricken rural subsistence population and several large national parks, including the Kruger National/Limpopo Transfrontier Park.…”

Section: Introductionmentioning

confidence: 99%

“…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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“…The region's water resources, agriculture, and rural communities are impacted considerably due to high rainfall variability (Cook et al 2004). It is imperative to perform spatial temporal variability analysis of rainfall at monthly or seasonal timescales to determine the likelihood of extreme (drought or flood) events occurrences and or return periods.…”

Section: Introductionmentioning

confidence: 99%

Variability of rainfall over Lake Kariba catchment area in the Zambezi river basin, Zimbabwe

Muchuru

Botai

et al. 2015

Theor Appl Climatol

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In this study, average monthly and annual rainfall totals recorded for the period 1970 to 2010 from a network of 13 stations across the Lake Kariba catchment area of the Zambezi river basin were analyzed in order to characterize the spatial-temporal variability of rainfall across the catchment area. In the analysis, the data were subjected to intervention and homogeneity analysis using the Cumulative Summation (CUSUM) technique and step change analysis using rank-sum test. Furthermore, rainfall variability was characterized by trend analysis using the non-parametric Mann-Kendall statistic. Additionally, the rainfall series were decomposed and the spectral characteristics derived using Cross Wavelet Transform (CWT) and Wavelet Coherence (WC) analysis. The advantage of using the wavelet-based parameters is that they vary in time and can therefore be used to quantitatively detect time-scale-dependent correlations and phase shifts between rainfall time series at various localized time-frequency scales. The annual and seasonal rainfall series were homogeneous and demonstrated no apparent significant shifts. According to the inhomogeneity classification, the rainfall series recorded across the Lake Kariba catchment area belonged to category A (useful) and B (doubtful), i.e., there were zero to one and two absolute tests rejecting the null hypothesis (at 5 % significance level), respectively. Lastly, the long-term variability of the rainfall series across the Lake Kariba catchment area exhibited non-significant positive and negative trends with coherent oscillatory modes that are constantly locked in phase in the Morlet wavelet space.

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Wet and dry spells within particularly wet and dry summers in the South African summer rainfall region

Cited by 174 publications

References 18 publications

Dynamical seasonal prediction of Southern African summer precipitation

Dynamical seasonal prediction of Southern African summer precipitation

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

Variability of rainfall over Lake Kariba catchment area in the Zambezi river basin, Zimbabwe

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