Abstract
The study analysed variation in surface temperature (ST) in Makurdi Urban Area (MUA), Northcentral Nigeria. A total of 12 Landsat TM/ETM+ images were acquired in January, April and June of 1991, 1996, 2001 and 2006. The ST was estimated from the 12 Landsat TM/ETM+ images, grouped into seven classes, and the area of each ST class was determined using remote sensing and Geographic Information System (GIS). The ST magnitudes vary spatially from 27.5oC (water bodies) to 50.7oC (built-up land), representing an intensity of 23.2oC. The mean seasonal ST varies from 32.4oC-34.5oC (cool-dry season), 35.5oC-38.8oC (hot-dry season) and 30.8oC-31.4oC (hot-wet season). The mean annual ST has increased from 32.9oC (1991) to 35.9oC (2006) with ST intensity of 3.0oC. The ST classes of 27oC-29oC and 33oC-37oC recorded the highest loss and gain in area of -126.5km2 and 94.5km2 whereas ST classes of 29oC-33oC and 41oC-45oC recorded the least and highest per centage change in area of 22% and 768%. The result showed decreasing and increasing trends in the areas of cooler and warmer surfaces, which are attributed to increase in anthropogen surface materials, with higher heat storage capacities, due to urbanisation.
Highlights
Surface temperature, refered to as brightness temperature (Chen et al, 2006), is the temperature of radiatively active natural and anthropogenic surface materials that absorb and store radiant energy
The surface temperature (ST) or land surface semperature (LST) forms an important climate variable that related to climate change (Kayet et al, 2016).Surface temperature is important in urban studies because it has considerable impact on urban thermal environment causing urban heat isalnds (UHIs) (Dissanayake et al, 2019) and controls surface heat and water exchange with the atmosphere (Gallo et al, 1993)
The maximum mean seasonal ST occurred in hot-dry seasonl, followed by cool-dry season and least in hot-wet season reflecting the seasonal variation in surface receipt of solar radiation and surface heat storage
Summary
Refered to as brightness temperature (Chen et al, 2006), is the temperature of radiatively active natural and anthropogenic surface materials that absorb and store radiant energy. The ST or LST forms an important climate variable that related to climate change (Kayet et al, 2016).Surface temperature is important in urban studies because it has considerable impact on urban thermal environment causing urban heat isalnds (UHIs) (Dissanayake et al, 2019) and controls surface heat and water exchange with the atmosphere (Gallo et al, 1993). In conjunction with Geographic Information System (GIS), has been widely applied in detecting land use/land cover change, the basis for the inadvertent climatic modification of cities (Weng, 2001), assessing the distribution characteristics of surface temperature and surface urban heat island (SUHI) (Weng, 2001; Weng et al, 2006) and investigating the relationship between surface temperature and land use/land cover (Zhang et al, 2004; Chen et al, 2006; Yuan & Bauer, 2007). The major objectives of the study are to: (1) retrieve and estimate ST (oC) from Landsat EM/ETM+ Images, (2) categorise ST (oC) in seven classes and (3) analyse the variation in the magnitude and intensity of ST, and areas of the ST classes
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