Investigation of Heat Wave Characteristics Over Selected Stations in Nigeria

In this study, the excess heat factor (EHF) index was applied in five (5) selected stations in Nigeria to investigate heat wave characteristics. The EHF originally introduced for use in Australian heatwave monitoring and forecasting, has now been incorporated into a newly designed climpact R-based package used in this work. This work had analysed over 30 years of daily precipitation, minimum and maximum temperature data, as the climate base period, for the selected stations: guinea savannah: Lokoja, Minna; sudan savannah: Kano; sahel: Sokoto, Maiduguri. Daily input data were checked for quality and homogeneity by the climpact software, which also computed and plotted the indices.

Sokoto, Kano, and Minna had the highest heat wave number of six (6), nine (9), and seven (7) respectively in 1987, Maiduguri had highest heat wave number of seven (7) in 1983 while Lokoja had highest heat wave number of five (5) and four (4) in 2005 and 1987 respectively. The lengthiest and shortest heat wave duration (HWD) was identified in 1983 and 1997 respectively for Sokoto, in 1991 and 2005 respectively for Maiduguri, while Kano and Lokoja had the same pattern of heat wave duration over the years. Maiduguri had higher heat wave frequencies than other stations.

Sokoto and Maiduguri had close to severe conditions based on their magnitude levels for both the heat wave amplitude and mean magnitude. Whereas, in Kano there was an almost constant heat wave amplitude and mean magnitude condition over the years. In Minna, opposite conditions as against Maiduguri were identified.

Generally, all results indicated moderate conditions, since severe or even extreme cases rarely occurred. This implied that the southern Sahel and the savannah stations investigated in this study have not been highly affected by heat wave conditions but at some moderate levels over the years under investigation.