A Synthesized Effect of Urban Modification and Net Radiation on the Climate of Lagos Metropolis, Nigeria

IBEABUCHI Uwadiegwu; Oni Feyi; Adeaga Olusegun A.

doi:10.37591/jonet.v10i3.4512

Abstract

Land cover adjustment which includes urban landscaping, agriculture crops or hardscapes forconstructing and parking lots promote variations in the energy and radiation balance. Due tothe above listed modifications, the surface temperatures and near-surface air temperatures overurban patches are generally higher than those over rural areas, thus resulting in an Urban HeatIsland (UHI). In this study, urban landscape and Land Surface Temperature (LST), netradiation, and Normalized Difference Vegetation Index (NDVI) data were extracted usingremote sensing and GIS (Geographic Information System) were used to synthesize effect ofurban modification and net radiation on the climate of Lagos metropolis. The urban landscapewas estimated and a rapid increase was witness in the urban built-up area, 54.05 km2 between1984–2000, 270.02 km2 between 2000–2013 With a reductions in rural built-up area, urbanizedopen land, rural open land and water body between 1984–2000 and 2000–2013 this revealsthat a wide margin is observed to exist between urban built-up and rural built-up area whichimplies that Lagos metropolis is highly urbanized. LST was found to have a mean of 23.05°Cfor 1984, 25.99°C for 2000, and 26.66°C for 2013. Net radiation was found to have a mean of449.43 W/m-2for 1984, 376.80 W/m-2for 2000, and 253.48 W/m-2for 2013. In synthesizing theeffects of factors of urban climate on Lagos metropolis factor analysis used and followingfactors were identified such: urbanized area, NDVI, LST, and net radiation. And a significantcorrelation exists between listed factors in Lagos metropolis. The result reveals that two factorswere selected: (1) the effect of urbanization on LST and urban surface modification (usingNDVI) and (2) the effect of LST on urban climate due to effect of net radiation. Based on theselected components, UHI areas were determined for Lagos metropolis using the urbanizedarea to delineate the urban built-up area from the rural built-up area, with reference to LST.Based on research findings, possible mitigation measures as means of controlling the menaceof the UHI were highlighted for the study area.