Simulation of the Rainfall Regime over Ghana from CORDEX

Owusu, Kwadwo; Klutse, Nana Ama Browne

doi:10.4236/ijg.2013.44072

Cited by 17 publications

(12 citation statements)

References 10 publications

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“…For example, [4] concentrated on Accra and Tamale, [5] concentrated on Tamale, [1] focused on Wenchi, and [9] focused on northern Ghana. However, few studies have considered Ghana as a whole: [10] used 16 stations in Ghana to study the trend in the rainfall pattern over the period from 1960 to 2005, while [11] used RCMs models to study the spatial pattern of rainfall over Ghana. The current study focuses on the rainfall variability over the whole of Ghana.…”

Section: Introductionmentioning

confidence: 99%

Rainfall Variability over Ghana: Model versus Rain Gauge Observation

Nkrumah¹,

Klutse²,

Adukpo³

et al. 2014

IJG

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This paper used the International Centre for Theoretical Physics (ICTP) Regional Climate Model, Version 3 (RegCM3) and rain gauge data selected from the Ghana Meteorological Agency (GMet) from 1990 to 2008 to investigate the extent and nature of variability in the annual rainfall and pattern of the raining seasons in Ghana. In the study, six meteorological stations selected from three rainfall distribution zones according to the divisions of the GMet were used to study the pattern of rainfall and its departure from the normal trend. The study also assessed the performance of the RegCM3 simulation with reference to the observed gauge data. Results confirmed the unimodal nature of the rainfall annual cycle over the northern belt and bi-modal rainfall nature over the middle and southern belts of Ghana. Negative departures of rainfall implying consistent downward trend were observed at all the stations. Our analysis showed that RegCM3 captured the average rainfall over Ghana but demonstrated an underestimation as compared to the observed gauge data. The model also had difficulty stimulating the departures accurately in direction and in magnitude in all the stations except for Accra where RegCM3 simulated the right direction of the departures.

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Section: Introductionmentioning

confidence: 99%

Rainfall Variability over Ghana: Model versus Rain Gauge Observation

Nkrumah¹,

Klutse²,

Adukpo³

et al. 2014

IJG

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“…A single wet season is thus experienced in the Savannah and Sahel Zones of West Africa between April to October when the ITD moves to its northernmost position. The southern part of the country on the other hand experiences two wet seasons: the first one which is the major wet season from March to July and the minor wet season from September to November [8,14,16,27].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Long-Term Spatio-Temporal Rainfall Variability over Ghana using Wavelet Analysis

Baidu

Amekudzi

Aryee

et al. 2017

Climate

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Abstract:Rainfall variability has strong impact on food security, livelihood and socio-economic activities as farming in West Africa is mainly rain-fed. The annual, seasonal and decadal rainfall variability over Ghana has been studied and their periodicities analysed using wavelet analysis. A rainfall time series from 1901-2010 from the Global Precipitation Climatology Center (GPCC) was used in this analysis. It was observed that high mean annual rainfall totals ranging from 900-1900 mm are recorded over the entire country. In addition, very high totals between 1500-1900 mm are recorded at the South-Western part of the country whereas low totals (900-1200 mm) are recorded in the Savannah and East coast of the country. In general, a decreasing trend was observed for the annual rainfall over all the agro-ecological zones except for the coastal zone, where a slight increasing trend of 0.1600 mm per year was seen. The seasonal trend analysis revealed a significant decreasing trend at 0.01 significance level in all the agro-ecological zones except for the Savannah during the DJF season indicating an intensification of the Harmattan. The Coastal zone recorded the lowest mean rainfall values for all seasons with the highest of about 150 mm in MAM. The Forest zone on the other hand recorded very high rainfall values for all seasons with the maximum of about 200 mm in JJA. The Transition zone, however, recorded almost quite stable rainfall amount for all seasons except for DJF. On the decadal time scale, below normal rainfall values were observed between the 1901-1920 and 1980-2010 periods for almost all the agro-ecological zones except for the Savannah which showed above normal rainfall values within the 1901-1940 period. Indicating that, the decreasing trend observed in recent years is not solely due to antropogenic factors but have a strong contribution from a natural climate variability. The wavelet analysis also revealed a strong annual periodicity over all the agro-ecological zones except for the Coastal and Forest zones where the annual periodicity was accompanied by 4-8 months signal. The results of both the 5 year moving average and the decadal anomaly confirm a significant decrease in rainfall amount. This will have negative consequences on agricultural practices, water resource management and food security.

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“…For example, it has been used within the CORDEX suite of RCMs (e.g. Awange et al 2013, Meque and Abiodun 2015, Owusu and Klutse 2013, Lejeune et al 2015 as well as in multiple weather@home projects as part of climateprediction.net (www.climateprediction.net/weatherathome/) , resulting in multiple publications isolating human and natural influences on observed climate events (see e.g. Sippel and Otto 2014, Anel et al 2014, Rosier et al 2015, Bergaoui et al 2015, Marthews et al 2015, Sippel et al 2015, Schaller et al 2016.…”

Section: Methodsmentioning

confidence: 99%

The Guiana Shield rainforests—overlooked guardians of South American climate

Bovolo

Wagner

Parkin

et al. 2018

Environ. Res. Lett.

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Tropical forests are global climate regulators through their interaction with hydrological and biogeochemical cycles. Despite extensive research on deforestation in South America and its global impact, the role of the largely intact Guiana Shield forests, north of the Amazon, has not yet been considered as part of this climate system. We use a regional climate model with a realistic deforestation scenario to test the impact of deforestation in the Guiana Shield on climate throughout South America. We show that replacing ∼28% of the current Guiana Shield rainforest with savannah leads to multi-scale impacts across South America, through vegetation-land-atmosphere interactions that disrupt the initial phase of two major 'atmospheric rivers': the Caribbean low-level Jet and the South American low-level jet (SALLJ). Our climate simulations suggest that following deforestation, locally, precipitation and runoff would more than double in lowland forests, whilst mean annual temperatures would increase by up to 2.2• C in savannahs. Regionally, significant wetting is simulated in northern South America (April−September) and the western Amazon (October-March), while temperatures increase up to 2• C in central and eastern Amazon, causing more dry months in up to 64% of the Amazon basin. Reduction of moisture transfer by the SALLJ of 2.2% of total annual flow causes noticeable and highly diverse spatial changes in simulated monthly rainfall in la plata basin (LPB). These results highlight the potential consequences of land cover change in a sensitive hot-spot with hydro-climatic impacts 1000 km west and 4000 km south. Such multi-scale perturbations can severely impact biodiversity and ecosystem services across South America, including agriculture in LPB. Recognition of the far field effects of localised deforestation in key areas is urgently needed to improve development plans for a sustainable future. Significance statementThe Guiana Shield, at the northern boundary of Amazonia, is located at the start of two atmospheric rivers which carry moisture across South America. We show that deforesting less than a third of the Guiana Shield, in areas currently under threat from mining, logging and agricultural activities, could result in significant changes in the water cycle across the continent. This includes large variations in temperature and precipitation affecting areas 4000 km away, impacting ecosystems and economies, with consequences for society. The study demonstrates how land-use change, even if small in spatial scale, but occurring in particularly sensitive hot-spots, can alter the flow of atmospheric rivers, with large consequences. This pan-continental cascade must be considered when designing trans-national management plans for a sustainable future.

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Simulation of the Rainfall Regime over Ghana from CORDEX

Cited by 17 publications

References 10 publications

Rainfall Variability over Ghana: Model versus Rain Gauge Observation

Rainfall Variability over Ghana: Model versus Rain Gauge Observation

Assessment of Long-Term Spatio-Temporal Rainfall Variability over Ghana using Wavelet Analysis

The Guiana Shield rainforests—overlooked guardians of South American climate

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