Abstract
This paper computes heat (cold) waves for four homogeneous temperature regions over West Africa based on excess heat (cold) index and heat (cold) stress. Era Interim daily minimum and maximum temperature data, National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis mean daily sea level pressure, 850 hPa winds and 500 hPa geopotential height are used as the surrogate observed data while simulated data are outputs of three Coordinated Regional Climate Downscaling Experiment models (CNRM-ARPEGE, SMHI-RCA and UQAM-CRCM). Heat (cold) wave is calculated for 2001-2008 with respect to 1989-2000 reference period. Findings show that heat wave fluctuates with Intertropical Convergence Zone (ITCZ) from Guinea-Savannah (GS) region in February-March to the Western Sahel between June and August. Frequency of heat waves is fairly stable except in 2007 and 2008 when it increases. The amplitude of heat wave increases from 2001 to 2008, probably due to global warming. With respect to the reanalysis; CNRM-ARPEGE, SMHI-RCA and UQAM-CRCM all simulate comparable spatial and temporal variations in heat waves. However, SMHI generally overestimates the magnitude of heat waves. The models also simulate cold waves similar to the Era Interim except at GS. [...]
Highlights
June-August (JJA) and September-November (SON) thanThere has been more temperature increase in the other seasons at the Guinea coast and Sahel in Nigeria
This paper aims at studying the variability of heat and cold waves in homogeneous temperature region over West Africa
The Principal Component Analysis (PCA) conducted on the 4383 days starting from 1st of January 1989 to 31st December 2000 over 2310 grids yield nine significant PCs based on the Cartell [1960] Scree criteria and eigenvalue one rule, Kaiser [1960]
Summary
June-August (JJA) and September-November (SON) thanThere has been more temperature increase in the other seasons at the Guinea coast and Sahel in Nigeria. ADENIYI AND OYEKOLA precipitation indices in Kaduna (Northern Nigeria) They found warming trends, increase in number of cool nights, more warm days; strong increase in the number of warm spells, slight increase in annual total rainfall and changes in the maximum number of extremely wet days. In West Africa, Mouhamed et al [2013] investigated the trends in extreme temperature and precipitation over the Sahel from 1960-2010 They found negative trend in frequency of cool nights, increase in frequency of warm days and spells, reduction in annual total rainfall and maximum number of consecutive wet days. All these findings suggest that further studies should be carried out on heat and cold waves variations over West Africa. Regional climate models should be used to carry out this study to determine the applicability of such models to the future projection of heat and cold waves over West Africa because of the possible disastrous impacts of such in any locality [Guirguis et al, 2014; Parmesan et al, 2000]
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