Abstract
ABSTRACTThe present study focuses on determining the relationship of estimated land surface temperature (LST) with normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI) for Florence and Naples cities in Italy using Landsat 8 data. The study also classifies different land use/land cover LU–LC) types using NDVI and NDBI threshold values, iterative self-organizing data analysis technique and maximum likelihood classifier, and analyses the relationship built by LST with the built-up area and bare land. Urban thermal field variance index was applied to determine the thermal and ecological comfort level of the city. Several urban heat islands (UHIs) were extracted as the most heated zones within the city boundaries due to increasing anthropogenic activities. The difference between the mean LST of UHI and non-UHI is 3.15°C and 3.31°C, respectively, for Florence and Naples. LST build a strong correlation with NDVI (negative) and NDBI (positive) for both the cities as a whole, especially for the non-UHIs. But, the strength of correlation becomes much weaker within the UHIs. Moreover, most of the UHIs (85.21% in Naples and 76.62% in Florence) are developed within the built-up area or bare land and are demarcated as an ecologically stressed zone.
Highlights
The urban heat island (UHI) effect indicates the higher air and land surface temperature (LST) in urban areas in comparison to the surrounding rural area, generated by high levels of near-surface energy emission, solar radiation absorption of ground objects and low rates of evapotranspiration (Buyantuyev & Wu, 2010; Kleerekoper, van Esch, & Salcedo, 2012; Oke, 1982, 1997; Rizwan, Dennis, & Liu, 2008)
A large number of studies considered that the built-up area and bare land accelerate the effect of UHI, whereas green space and water reduce the UHI intensity (Amiri, Weng, Alimohammadi, & Alavipanah, 2009; Song, Du, Feng, & Guo, 2014)
To analyse the changes in temperature and land use/ land cover (LU–LC) types in the study region, the normalized difference vegetation index (NDVI) and normalized difference builtup index (NDBI) were applied for determining the correlation with derived LST
Summary
The urban heat island (UHI) effect indicates the higher air and land surface temperature (LST) in urban areas in comparison to the surrounding rural area, generated by high levels of near-surface energy emission, solar radiation absorption of ground objects and low rates of evapotranspiration (Buyantuyev & Wu, 2010; Kleerekoper, van Esch, & Salcedo, 2012; Oke, 1982, 1997; Rizwan, Dennis, & Liu, 2008). The relationship between landscape pattern and UHI becomes globally considerable (Chen, Yao, Sun, & Chen, 2014; Coseo & Larsen, 2014; Du et al, 2016a; Du, Xiong, Wang, & Guo, 2016b; Li, Song, Cao, Meng, & Wu, 2011; Peng, Xie, Liu, & Ma, 2016). Some researchers have found that natural and socio-economic factors simultaneously create certain effects on LST pattern (Buyantuyev & Wu, 2010; Jenerette et al, 2007; Kuang et al, 2015)
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