East African Rainfall Anomaly Patterns in Association with El Niño/Southern Oscillation

Ntale, Henry K.; Gan, Thian Yew

doi:10.1061/(asce)1084-0699(2004)9:4(257)

Cited by 42 publications

(25 citation statements)

References 18 publications

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“…Similar methods have been employed with Table 1. success in several previous teleconnection studies (e.g., Fleming et al, 2007;Gershunov, 1998;Gobena & Gan, 2006;Ntale & Gan, 2004;Piechota & Dracup, 1996). Statistical significance of the conditional composites was determined by a two-sided bootstrap test whereby 10,000 synthetic composites were generated by resampling with replacement from the original data.…”

Section: Methodsmentioning

confidence: 99%

The Role of Large-Scale Climate Modes in Regional Streamflow Variability and Implications for Water Supply Forecasting: A Case Study of the Canadian Columbia River Basin

2013

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The impacts of large-scale modes of climate variability on the annual cycle of terrestrial hydrometeorology in the Canadian Columbia River basin were assessed with the aim of updating our current understanding and identifying opportunities for climate-informed, early-season water supply forecasting. Composite analyses of streamflow from seven Water Survey of Canada gauging stations conditional on El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Pacific/North American pattern (PNA), Arctic Oscillation (AO), and North Pacific Gyre Oscillation (NPGO) states revealed that hydrological impacts of a climate mode could be manifested through changes in the annual runoff volume and/or changes in seasonal runoff patterns. Responses were generally non-linear. Considering ENSO and the PDO, for instance, streamflow anomalies associated with their warm phases contrast with those associated with their cool phases; however, the warm phases tend to produce more consistent streamflow responses than the cool phases. More profoundly, the PNA and AO streamflow responses appear to be highly asymmetrical-only one phase (positive PNA and negative AO) is shown to significantly affect streamflow. Some North Pacific climate indices and ENSO show reasonably consistent and strong correlations with streamflow, which suggests that further refinement of climate-informed early season water supply forecasting is possible. It is shown that further improvement of forecast skills can be attained if North Pacific climate information is included in addition to ENSO in the current generation of operational statistical water supply forecast models.

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Section: Methodsmentioning

confidence: 99%

The Role of Large-Scale Climate Modes in Regional Streamflow Variability and Implications for Water Supply Forecasting: A Case Study of the Canadian Columbia River Basin

2013

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“…Inter-annual variations in Uganda's rainfall are thought to be connected to sea-surface temperature (SST) gradient fluctuations, especially the El Niño Southern Oscillation (ENSO) (Mutai et al, 1998;Indeje et al, 2000;Mutai & Ward, 2000;Ntale & Gan, 2004). ENSO teleconnections affect the northern and southern regions of Uganda differently.…”

Section: Climate In Ugandamentioning

confidence: 99%

Multi-site stochastic modelling of daily rainfall in Uganda

Kigobe

McIntyre

Wheater

et al. 2011

Hydrological Sciences Journal

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The availability of precipitation records in Uganda has significantly decreased since the 1970s, severely limiting the data available for hydrological modelling. This problem has been addressed in this study by using the generalized linear modelling (GLM) framework to develop stochastic daily rainfall models that have the capability for extending and infilling historic data sets. We have used a relatively sparse raingauge network in the Kyoga basin (in the Upper Nile) to reproduce spatial and temporal patterns of precipitation by fitting occurrence (logistic) and amounts (gamma) models as functions of dominant seasonal, climate and geographical controls. The GLMs were able to reproduce rainfall properties when predefined climatic zones are modelled independently. We were not able to represent the spatial variability of the equatorial climate with one integrated basin scale model, however this is not thought to preclude application to basin scale hydrological modelling.Key words generalized linear models; rainfall; stochastic models; climate change; Uganda; Kyoga; ENSO Modélisation stochastique multi-sites de la pluie journalière en Ouganda Résumé La disponibilité des données de précipitations en Ouganda a considérablement diminué depuis les années 1970, limitant fortement les données disponibles pour la modélisation hydrologique. Ce problème a été abordé dans cette étude dans le cadre de la modélisation linéaire généralisée (MLG), afin de développer des modèles stochastiques de pluie journalière qui puissent étendre et compléter les données historiques. Nous avons utilisé un réseau de pluviomètres de relativement faible densité dans le bassin du Kyoga (dans le Nil Supérieur), afin de reproduire les patrons spatiaux et temporels des précipitations en modélisant l'occurence (logistique) et les volumes (gamma) comme fonctions des forçages dominants saisonniers, climatiques et géographiques. Les MLG sont en mesure de reproduire les propriétés des pluies lorsque des zones climatiques pré-définies sont modélisées de façon indépendante. Nous n'avons pas pu représenter la variabilité spatiale du climat équatorial avec un modèle à l'échelle intégrée du bassin, cependant ceci ne semble pas devoir empêcher la mise en oeuvre d'une modélisation hydrologique à l'échelle du bassin.

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“…Nevertheless, rainfall variability over the East Africa with relation to regional and remote atmospheric and oceanographic parameters has been studied by many researchers (e.g. [3][4][5][6][7][8][9][10][11]). …”

Section: Introductionmentioning

confidence: 99%

Climate Characteristics over Southern Highlands Tanzania

Mbululo¹,

Nyihirani²

2012

ACS

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This study was conducted to examine the climate characteristic of southern highland Tanzania (Latitude 6˚S -12˚S and Longitude 29˚E -38˚E). The study findings reveal that rainfall over the region is linked with SST over the Indian Ocean, where warmer (cooler) western Indian Ocean is accompanied by high (low) amount of rainfall over Tanzania. During wet (dry) years, weaker (stronger) equatorial westerlies and anticyclone (cyclonic) anomaly over the southern tropics act to reduce (enhance) the export of equatorial moisture away from East Africa. The wettest (driest) season was found to be 1978/79 (1999/00) which can be classified as the severely wet (moderate drought). Two different modes of rainfall have been identified at time scale of 1.5 and 6 years which have been associated with the quasi biennial oscillation (QBO) and El Nino Southern Oscillation (ENSO), respectively.

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East African Rainfall Anomaly Patterns in Association with El Niño/Southern Oscillation

Cited by 42 publications

References 18 publications

The Role of Large-Scale Climate Modes in Regional Streamflow Variability and Implications for Water Supply Forecasting: A Case Study of the Canadian Columbia River Basin

The Role of Large-Scale Climate Modes in Regional Streamflow Variability and Implications for Water Supply Forecasting: A Case Study of the Canadian Columbia River Basin

Multi-site stochastic modelling of daily rainfall in Uganda

Climate Characteristics over Southern Highlands Tanzania

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