Influence of different land cover types on land surface temperature - case study of the Lucknow city in India

Abstract

With the increase of urbanization, the urban heat island phenomenon is becoming more noticeable and concerning. This effect occurs when the temperatures are higher in urbanized areas than in suburban and rural areas. The aim of this study is to analyze the influence of different land cover types on the land surface temperature (LST) and the surface urban heat island (SUHI) effect. The study was conducted on imagery acquired in September by Landsat 8 OLI TIRS satellite. The selected area was the city of Lucknow (India) and its surroundings. The climate is subtropical, seasons are clearly distinguishable - winters are cold, summers are hot and dry. Land cover types were determined using supervised classification and Normalized Difference Vegetation Index. Land surface temperature was calculated. The influence of different land cover on LST and SUHI phenomenon was analyzed by using visual analysis, comparing average temperatures of land cover classes, creating temperature profile and calculating Urban Thermal Field Variance Index to analyze the intensity of SUHI. The type of land cover affects land surface temperature therefore has an impact on the SUHI phenomenon. Build-up areas show much higher land surface temperature than non-urban, vegetated areas. The spatial distribution of these forms of land cover, i.e. the cumulative built-up area forming the city and the green areas around the city, combined with the with their characteristic surface temperatures, result in an surface urban heat island effect. Average temperatures of non-natural surfaces are around 5°C higher than average temperatures of natural surfaces. UTFVI indicates that the intensity of SUHI phenomenon is the highest in build-up and bare soil land cover classes, and the lowest for vegetation and water areas. The intensity also varies within a single class, in urban areas UTVI is higher in the center and decreases toward the vegetation class. The LST values and temperature profile indicates that the higher temperature of non-natural land cover forms affects not only the increased temperature of the surface on which they are located but also the areas in the close neighborhood. Temperature within the same land cover class of agricultural areas and meadows areas is higher when measured in the vicinity of the urban class.