LAND SURFACE TEMPERATURE IN PART OF SOUTH-WEST NIGERIA (1991 - 2015)

Abstract

The study examined the spatial and temporal variation of land surface temperatures over a typical medium-size traditional settlement in southwestern Nigeria. Data were the multi-date satellite Landsat imageries (1991, 2002 and 2015) covering the area, as well as values of ambient air temperatures that were measured at different landuse areas (industrial, commercial, residential and outskirts) and along the major road that traverse the study area using a portable handheld air weather station thermometer. Ambient temperature values were obtained between 0600 and 1900 hours of the Nigerian local standard time. Analysis of the Landsat imageries indicate that thermal reflectance (in terms of normalized difference build-up index, NDBI) has generally increased between 1991 and 2015 by about 92 %. The NDBI shows that temperature has increased over the built up regions by 49 - 52 % between 1991 and 2015. Average land surface temperature (LST) in the area also increased by about 2.2 oC (22.8 oC - 25 oC) in the study period, but with higher than average increase around road junctions, industrial and commercial centres. Analysis of diurnal variation showed that daytime temperature was about 0.5 - 1.4 oC higher in the afternoon than either the morning or evening. The study concluded that increased in anthropogenic activities, including urbanization and commercialization are main causes of temperature increase in the traditional area, and that remote sensing imageries and in situ measurements of temperature are complementary for monitoring of changes in urban climate.

Keywords

• landsat imageries
• land surface temperature (LST)
• traditional urban settlement
• Normalized Difference Building Index