TITLE:
Comparison of Rainy Season Onset, Cessation and Duration for Ghana from RegCM4 and GMet Datasets
AUTHORS:
Caleb Mensah, Leonard K. Amekudzi, Nana Ama B. Klutse, Jeffrey N. A. Aryee, Kofi Asare
KEYWORDS:
Onset, Cessation, Duration of Rainy Season, GMet, Ghana, RegCM4
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.6 No.2,
April
25,
2016
ABSTRACT: 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.