Browsing by Author "Mensah, Caleb"

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    Comparison of rainy season onset, cessation and duration for Ghana from RegCM4 and GMet Datasets
    (Atmospheric and Climate Sciences, 2016-04-25) Mensah, Caleb; Amekudzi, Leonard K.; Klutse, Nana Ama B.; Aryee, Jeffrey N. A.; Asare, Kofi
    The socio-economic sector of West African countries is rain-fed agriculture driven. Information regarding the onset, cessation and duration of the rainy season is thus, very essential. In this paper, a comparison of the onset, cessation and duration of the rainy season has been carried out using simulated rainfall data from the fourth generation Regional Climate Model (RegCM4) and rain gauge measurements from Ghana Meteorological Agency (GMet), covering a period of 1998 to 2012. Similar onset and cessation dates were seen in both the simulated and guage rainfall measurements for the various agro-ecological zones, resulting in similar duration of the rainy season. The average duration of the rainy season were less than 200 days for the savannah and coastal zones whereas the duration of the rainy season were beyond 200 days for the forest and transition zones. The bias of these comparisons was less than 30 days and the root mean square error (RMSE) values were less than 15 days for all stations, except Saltpond. The Pearson’s correlation (r) typically ranged between 0.4 and 0.8. However, negative correlations were observed for Tamale in the savannah zone, and the entire coastal zone. These findings are indications that RegCM4 has the potential to clearly simulate the movement of the rain belt, and thus, could fairly determine the onset, cessation and duration of the rainy season. The findings have significant contributions to effective water resource management and food security in Ghana, as the thriving of these sectors depend on the dynamics of the rainfall seasons.
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    Investigation of the Onset, Cessation and Length of the Rainy Season over Ghana
    (2015-04-09) Mensah, Caleb
    This study seeks to investigate the onset, cessation and length of the rainy season using a simulated rainfall data from the fourth generation Regional Climate Model (RegCM4) and measured rainfall data from the Ghana Meteorological Agency (GMet) over Ghana from 1998 to 2012. The results from the RegCM4 was compared with those derived from the measured rainfall data. The results showed that the mean rainfall onset dates for the Forest, Coastal, Transition and Northern zones of the country, from the RegCM4 was calculated to be 31st March, 4th April, 13th April and 2nd May respectively. The GMet measured rainfall values also had the mean rainfall onset dates determined to be 27th March, 27th April, 8th April and 27th April for the Forest, Coastal, Transition and Northern zones. The mean rainfall cessation dates from the RegCM4 was recorded to be 2nd November for the Forest zone, 29th October for the Coastal zone, 15th November for the Transition zone and 20th October for the Northern zone. The mean rainfall cessation dates from the GMet measured rainfall values was also determined to be 16th November for the Forest zone, 3rd November for the Coastal zone, 24th November for the Transitional zone and 9th November for the Northern zone. The average length of the rainy season from the RegCM4 was computed to be about 216 days for the Forest zone, 209 days for the Coastal zone, 216 days for the Transition zone and 171 days for the Northern zone. The GMet rainfall measured data also measured similar average lengths of 234 days for the Forest, 191 days for the Coastal zone, 230 days for the Transition zone and 196 days for the Northern zone. These results may have very useful applications for water resource management and food security in Ghana.