Simulation of the sensitivity of Lake Victoria basin climate to lake surface temperatures

Anyah, Richard; Semazzi, Fredrick H. M.

doi:10.1007/s00704-004-0057-4

Cited by 63 publications

(65 citation statements)

References 16 publications

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“…This is reasonably reproduced in the model climatology. The only notable exception is persistent wet conditions simulated over Lake Victoria, apparently contributed by the lake-induced localized convection (Anyah and Semazzi, 2004). The model simulates relatively higher rainfall amounts over Lake Victoria (Basin), but unfortunately CRU and CMAP datasets may not be used to satisfactorily validate the model output.…”

Section: Comparisons Between Simulated and Observed Monthly Rainfall mentioning

confidence: 99%

Variability of East African rainfall based on multiyear Regcm3 simulations

Anyah

Semazzi

2006

Intl Journal of Climatology

105

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Abstract:The International Center for Theoretical Physics (ICTP) regional climate model version 3 (ICTP-RegCM3) multiyear simulations of East Africa rainfall during the October-December, short rains season are evaluated. Two parallel runs; based on NCEP reanalysis and NASA FvGCM lateral boundary conditions are performed. The simulated monthly and seasonal rainfall climatology as well as the interannual variability are found to be fairly consistent with the observations. The model climatology over specific homogeneous climate subregions, except central Kenya (CKE) highlands, also reasonably agrees with the observed. The latitude-time evolution (intraseasonal variability) of the simulated seasonal rainfall exhibits two distinct modes of behavior. The first is a quasistationary mode associated with high rainfall throughout the season within the equatorial belt between 1°S and 2°N. The second mode is associated with the intertropical convergence zone (ITCZ)-driven southward migration of regions of rainfall maxima as the season progresses, which is also consistent with the observed. Furthermore, observed rainfall variability over distinct homogeneous climate subregions is also fairly reproduced by the model, except over central Kenya highlands and northeastern parts of Kenya. The spatial correlation between the simulated seasonal rainfall and some of the global teleconnections (DMI and Nino3.4 indices) shows that the regional model conserves some of the observed regional 'hot spots' where rainfall-ENSO/DMI associations are strong. At the same time, unlike observations, the model reveals that along the East Africa Rift Valley and over western parts of the Lake Victoria Basin, the association is weak, perhaps an indication that nonlinear interactions between local forcing (captured by the model) and large-scale systems either suppress or obscur the dominant influence of the teleconnections on rainfall over certain parts.

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Section: Comparisons Between Simulated and Observed Monthly Rainfall mentioning

confidence: 99%

Variability of East African rainfall based on multiyear Regcm3 simulations

Anyah

Semazzi

2006

Intl Journal of Climatology

105

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“…Large-scale climate oscillations can produce significant inter-annual variability in rainfall distributions in Equatorial Africa as elsewhere Anyah & Semazzi, 2004Yang et al, 2005). Hence, many stochastic rainfall models relate parameter values to large-scale climate indices.…”

Section: Stochastic Rainfall Modelsmentioning

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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“…The available observational records and historical information show that variations in the level of east African lakes are closely related to previous trends in rainfall patterns (see e.g Anyah and Semazzi 2004). The DSI values, presented in Table 4 illustrate the drought years in both Kyoga and Victoria drainage sub-basins in Uganda.…”

Section: Satellite Derived Changesmentioning

confidence: 79%

Detecting changes in surface water area of Lake Kyoga sub-basin using remotely sensed imagery in a changing climate

Nsubuga

Botai

Olwoch

et al. 2015

Theor Appl Climatol

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Detection of changes in Earth surface features, for example lakes, is important for understanding the relationships between human and natural phenomena in order to manage better the increasingly scarce natural resources. This work presents a procedure of using Modified Normalised Difference Water Index (MNDWI) to detect fluctuations of Lake surface-water area and relate it to a changing climate. The study used radiometrically and geometrically rectified Landsat images for 1986, 1995 and 2010 encompassing the Kyoga Basin lakes of Uganda, in order to investigate the changes in surface-water area between the respective years. The Standard Precipitation Index (SPI) and Drought Severity Index (DSI) are applied to show the relationship between variability of surface-water area and climate parameters. The present analysis reveals that surface-water area fluctuation is linked to rainfall variability. In particular, Lake Kyoga sub-basin lakes experienced an increase in surface-water area in 2010 compared to 1986. This work has important implications to water resources management for Lake Kyoga and could be vital to water resource managers across Ugandan lakes.

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Simulation of the sensitivity of Lake Victoria basin climate to lake surface temperatures

Cited by 63 publications

References 16 publications

Variability of East African rainfall based on multiyear Regcm3 simulations

Variability of East African rainfall based on multiyear Regcm3 simulations

Multi-site stochastic modelling of daily rainfall in Uganda

Detecting changes in surface water area of Lake Kyoga sub-basin using remotely sensed imagery in a changing climate

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