Land surface temperature and its relationship with land use/land cover and aerosol optical depth: a case study from Ahmedabad city, India.

Urban expansion and increasing aerosol concentrations significantly alter land surface properties, influencing local climate systems through variations in land surface temperature (LST); however, the combined long-term effect of atmospheric and surface drivers remains unaddressed in semiarid Indian cities. This study examines a long-term spatio-temporal relationship between land use and land cover (LULC) changes, aerosol loading through aerosol optical depth (AOD), and LST trends in Ahmedabad to analyze the influence of changing land cover and aerosol load on land surface temperature-related urban heat island, thermal comfort, and ecological quality. A multisensor remote sensing approach is utilized to retrieve LST and urban thermal field variance index (UTFVI) from Landsat data for the years 1993, 2002, 2014, and 2023, while MODIS AOD and LST products from 2002 to 2023 were used to analyze the diurnal response of LST. The results show substantial urban expansion of 171.15 sq.km from 1993 to 2023, accompanied by a sharp decline in fallow and vegetated land. Seasonal LST and UTFVI analysis indicate a polarized thermal environment, where the declining fallow land experiences the worst thermal comfort, whereas water bodies and vegetation provide excellent thermal comfort. LULC indices, such as NDVI and NDBI, support the cooling and warming nature of vegetation and built-up areas, respectively. Statistical correlations between AOD and LST confirmed the dual influence of AOD on surface thermal behavior. This study demonstrates thermal comfort as a function of surface management and atmospheric loading. These findings can help in refining the Ahmedabad Heat Action Plan, emphasizing the need for fallow land management and urban infrastructure to enhance the night-time urban climate resilience.