Estimation of Land Surface Temperature from Landsat-8 OLI Thermal Infrared Satellite Data. A Comparative Analysis of Two Cities in Ghana
2021
This
study employs Landsat-8 Operational Land Imager (OLI) thermal infrared
satellite data to compare land surface temperature of two cities in Ghana:
Accra and Kumasi. These cities have human populations above 2 million and the
corresponding anthropogenic impact on their environments significantly. Images were
acquired with minimum cloud cover (ere used. The shapefiles of Accra and Kumasi were used to extract from the
full scenes to subset the study area. Thermal band data numbers were converted
to Top of Atmospheric Spectral Radiance using radiance rescaling factors. To
determine the density of green on a patch of land, normalized difference
vegetation index (NDVI) was calculated by using red and near-infrared bands i.e. Band 4
and Band 5. Land surface emissivity (LSE) was also calculated to determine the
efficiency of transmitting thermal energy across the surface into the
atmosphere. Results of the study show variation of temperatures between
different locations in two urban areas. The study found Accra to have
experienced higher and lower dry season and wet season temperatures,
respectively. The temperature ranges corresponding to the dry and wet seasons
were found to be 21.0985oC to 46.1314oC, and, 18.3437oC to
30.9693oC respectively. Results
of Kumasi also show a higher range of temperatures from 32.6986oC to 19.1077oC during the dry season. In the wet season, temperatures ranged from
26.4142oC to -0.898728oC. Among the reasons for the cities of Accra
and Kumasi recorded higher than corresponding rural areas’ values can be
attributed to the urban heat islands’ phenomenon.
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