Spatial and Temporal Dynamics of Land Surface Temperature Over Addis Ababa and its Surrounding:GIS and a Remote Sensing-Based Study
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Date
2021-06-01
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Addis Ababa University
Abstract
This study has investigated the spatial, interannual and seasonal variation of land surface temperature
over Addis Ababa and its surrounding in central Ethiopia. The study used remote sensing data
products and different GIS spatial analysis tools. Dry and wet seasons Landsat TM (Thematic Mapper)
of 1986, Landsat ETM+ of 2000 and Landsat 8 OLI (Operational Land Imager) of 2017 were used. To
estimate land surface temperature, different indices such as NDVI, NDBI brightness temperature and
land surface emissivity were retrieved from the Landsat images of all study years and seasons. To
assess changes in land cover and land use from 1986 to 2017, land use and land cover classification
was conducted using the supervised image classification and the maximum likelihood algorithm
method. The result of the study showed rapid expansion of built-up area and cultivated land against
grazing lands and other land use classes and a reduction of vegetation cover from 1986 to 2017. NDVI
has showed a reduction across time particularly in the urban, suburban and other areas of the study. In
contrast to NDVI, NDBI has shown an increase over time, where higher NDBI is detected from urban
areas. Higher land surface emissivity was estimated from areas where there is better vegetation cover,
while lower land surface emissivity was detected in urban and non-vegetated areas. The interannual
analysis (1986-2017) of land surface temperature showed a net change ranging from -3ºC to 7ºC and it
is higher than seasonal variation of land surface temperature which ranges from -2ºC to 4ºC.
Particularly, land surface temperature is characterized by significant increase in urban and
non-vegetated areas. The spatial analysis revealed that land surface temperature has negative
correlation with NDVI and positive correlation with NDBI. This study recommends ground
measurement of land surface temperature to evaluate and calibrate land surface temperature estimated
from remote sensing products. This study generated useful information for designing strategies to
mitigate urban heat island effects.
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Keywords
Dynamics of Land Surface, Addis Ababa and its surrounding, Temperature