Heat island is known as the increases in air temperature through large and industrial cities compared to surrounding rural areas. In this study, remote sensing technology is used to monitor and track thermal variations within the city center of Baghdad through Landsat satellite images and for the period from 2000 to 2015. Several processors and treatments were applied on these images using GIS 10.6 and ERDAS 2014, such as image correction and extraction, supervised classification, and selection of training samples. Urban areas detection was resulted from the supervised classification linked to the temperature readings of the surface taken from the thermal bands of satellite images. The results showed that the surface temperature of the city of Baghdad increased by 8 degrees Celsius in 15 years. This is due to the increase in the expansion of the urban areas type of land use, where the human activity, especially after 2003, caused increased buildup area to about 198.41 km2. All these changes occurred at the expense of many green regions which were reduced, with the transformation of open and agricultural areas to residential, commercial, and industrial uses. Increases in surface temperature resulted increases in air temperature, where the minimum temperature showed larger increases relative to maximum temperature (about 1.44 and 0.76 ºC, respectively).

The research deals with the thermal island in Baghdad city and the effect of urban expansion on it. Cities are suffering from a marked rise in temperature, compared with the surrounding rural areas, this problem occurs in most cities of the world. The reason for their formation is the increasing of human activity in the form of city components, such as buildings and roads that replace green spaces and open spaces. This means that most of these materials have the ability to absorb solar radiation and convert it into heat energy that increases the heat of their environment. Remote sensing technique is used to determine the thermal island through using Landsat satellite images as well as the use of GIS technology in mapping and analysis of spatial variation for thermal island. Normalized Difference Vegetation Index (NDVI) is calculated to extract vegetation cover from 2003 to 2018. The land surface temperature is estimated from the thermal band of satellite images for the same period. The change in vegetation cover is linked to the change in land surface temperature to determine the effect of vegetation cover degradation on surface temperature, also to determine the relationship between thermal island and land uses. The values of NDVI was high in 2003 and it ranged from (-0.714 - 0.693); this indicates a high vegetal cover, while its value is decreased to (-0.22 - 0.509) in 2018, pointing out to the significant deterioration of vegetation cover in 15 years. The land surface temperature is increased from (10.93-36.26) in 2003 to (22.62-50.29) in 2018; all this at the expense of converting the green, open and agricultural areas to residential, commercial and industrial uses as well as the large number of random settlements that appeared in Baghdad after 2003.

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