Utilising geospatial data to understand urban heat island and its effect on urban thermal comfort in selected Indian cities using Remote Sensing and GIS

Urbanization, together with increasing global population pressure and climate variability, has introduced heat-related challenges across urban areas, severely impacting humans and the Earth. The rapid population growth has placed India at the top of the global population ranking. Demographic surges concentrate stress on existing urban systems, making Indian metropolises-both inland hubs and rapidly transforming coastal centers-critical laboratories for studying UHI dynamics.

The understanding of patterns and possible causes of the UHI effect due to urbanization-induced anthropogenic activities is a vital area in urban climate research. This study presents an overall multi-decadal day/night spatiotemporal seasonal analysis and trends in LST and UHI for six Indian cities: Ahmedabad, Mumbai, Panjim, Mangalore, Kochi, and Thiruvananthapuram, spanning the last three decades.

MODIS LST and AOD data are used to explain the possible reasons for the change in LST and UHI, focusing on the seasonal thermal behavior of cities under prevailing atmospheric, meteorological, and anthropogenic conditions. The Landsat series datasets are used to develop LULC maps and delineate high-resolution UHI zones, to explain shared trajectories and city-specific patterns that expose complex vulnerabilities within urban ecosystems in India. The findings, which integrate multi-decadal 30-year satellite-derived LST, LULC, and AOD data, demonstrate that greater increases in nighttime LST are associated with a decrease in the diurnal temperature range across all cities. Mumbai consistently showed lower mean LST values compared to Ahmedabad, which exhibited substantially higher values and extreme seasonal amplitudes ranging from 17.23 °C to 50.05 °C. Goa and Mangalore depicted a 1-4 °C increase in seasonal mean LST between 1993 and 2023. Corresponding to a rise in built-up area and a decline in vegetation, Kochi too exhibited a rise in LST. Thiruvananthapuram showed a strong warming, with a mean LST increase of about 3°C. AOD patterns also demonstrated similar spatial and temporal gradients across cities, helping to reinforce land-use change, urban expansion, and inland-coastal climatic contrasts as the significant causes of LST trends.

Collectively, these findings reveal how land-use transition, and climatic variability, significantly alters the thermal environment of Indian cities; making such studies important for climate-responsive planning and better urban management to enhance resilience and thermal comfort.