Modification of the southern African rainfall variability/ENSO relationship since the late 1960s

Richard, Yves; Trzaska, S.; Roucou, Pascal; Rouault, Mathieu

doi:10.1007/s003820000086

Cited by 131 publications

(118 citation statements)

References 40 publications

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“…Neither temperature nor pressure was significant in the amounts model. Although the ENSO indices were expected to be important based on the literature (Richard et al, 2000;Mulenga et al, 2003;Reason et al, 2005;Manatsa et al, 2008), none of these indices were within the eight most statistically significant external predictors.…”

Section: Spatial and Temporal Predictorsmentioning

confidence: 94%

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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Section: Spatial and Temporal Predictorsmentioning

confidence: 94%

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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“…Several studies concluded that this interdecadal variability is modulated by ENSO-like decadal variability, which influences southern Indian Ocean SST and wind fields on multidecadal time scales (Allan et al 1995;Reason et al 1996;Reason and Rouault 2002). Richard et al (2000) proved that after the late 1960s, the influence of ENSO variability on South Africa rainfall increased, which is associated with a decrease in rainfall over certain areas. Reason and Rouault (2002) postulate that the remote influence of large-scale SST and sea level pressure (SLP) fields in the Indo-Pacific mainly influences the mean position of the tropical temperature troughs, the main rain-producing systems, and therefore, the amount of rainfall received in particular areas across southern Africa.…”

Section: Climate Of the Western Indian Ocean And Adjacent Continentsmentioning

confidence: 99%

“…India, East Africa, South Africa and Austral-Asia (Jury et al 2002). Several studies revealed that the atmospheric response to Indian Ocean SST changes is essential for simulating observed rainfall variability over large parts of Africa (Goddard and Graham 1999;Latif et al 1999;Clark et al 2000;Richard et al 2000;Reason and Mulenga 1999;Reason 2001;Reason and Rouault 2002;Jury et al 2004;Vecchi and Harrison 2004). Whatever the dominant forcing of decadal variability, it is clear that certain Indian Ocean SST patterns are related to drought or rain excess in certain regions of Africa and India.…”

Section: Introductionmentioning

confidence: 99%

Western Indian Ocean marine and terrestrial records of climate variability: a review and new concepts on land–ocean interactions since AD 1660

Zinke

Pfeiffer

Timm

et al. 2008

Int J Earth Sci (Geol Rundsch)

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We examine the relationship between three tropical and two subtropical western Indian Ocean coral oxygen isotope time series to surface air temperatures (SAT) and rainfall over India, tropical East Africa and southeast Africa. We review established relationships, provide new concepts with regard to distinct rainfall seasons, and mean annual temperatures. Tropical corals are coherent with SAT over western India and East Africa at interannual and multidecadal periodicities. The subtropical corals correlate with Southeast African SAT at periodicities of 16-30 years. The relationship between the coral records and land rainfall is more complex. Running correlations suggest varying strength of interannual teleconnections between the tropical coral oxygen isotope records and rainfall over equatorial East Africa. The relationship with rainfall over India changed in the 1970s. The subtropical oxygen isotope records are coherent with South African rainfall at interdecadal periodicities. Paleoclimatological reconstructions of land rainfall and SAT reveal that the inferred relationships generally hold during the last 350 years. Thus, the Indian Ocean corals prove invaluable for investigating land-ocean interactions during past centuries.

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“…Figure 1 presents the correlation field between a regional rainfall index over southern Africa (SARI; Richard et al, 2000) and SST over the Atlantic and Indian Oceans for the late austral summer season (January-March). It shows a core of positive SST anomalies in the central-southwestern part of the Atlantic Ocean in addition to the strong positive correlation with southwestern areas of the Indian Ocean.…”

Section: Introductionmentioning

confidence: 99%

Sea‐surface temperature co‐variability in the Southern Atlantic and Indian Oceans and its connections with the atmospheric circulation in the Southern Hemisphere

Fauchereau

Trzaska

Richard

et al. 2003

Intl Journal of Climatology

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132

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The relationship between sea-surface temperature (SST) inter-annual variability at the subtropical and midlatitudes of the southern Atlantic and Indian Oceans and its links with the atmospheric circulation in the Southern Hemisphere are investigated over the 1950-1999 period. Exploratory analysis using singular value decomposition and further investigations based on simple indices show that a large part of regional SST variability is common between the southwestern parts of both basins at subtropical and midlatitudes during the austral summer. Interestingly, these areas are also significantly associated with the far southwestern Pacific (Tasman Sea area). The patterns and time series of covariability between the southern Atlantic and Indian Oceans are shown to correspond to SST modes previously described in the literature as 'subtropical dipoles', independently for the Atlantic and Indian Oceans. Composite analyses show that austral summers characterized by simultaneous warm (and to a lesser extent cold) SST anomalies in the southwestern (northern) part of both southern oceans are related to atmospheric anomalies mainly involving a southward shift and a strengthening of the subtropical high-pressure systems over both basins. These anomalies are embedded in a hemispheric signal associating two cores of positive pressure anomalies within the South Pacific anticyclone. The global picture appears to have a wave number 4 spatial structure. The associated low-level wind and latent heat-flux anomalies and the lags between atmospheric variables and SST anomalies are consistent with an atmospheric forcing on the ocean. Potential links of these patterns with large-scale modes of climate variability in the Southern Hemisphere are discussed.

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Modification of the southern African rainfall variability/ENSO relationship since the late 1960s

Cited by 131 publications

References 40 publications

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

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

Western Indian Ocean marine and terrestrial records of climate variability: a review and new concepts on land–ocean interactions since AD 1660

Sea‐surface temperature co‐variability in the Southern Atlantic and Indian Oceans and its connections with the atmospheric circulation in the Southern Hemisphere

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