Urban Heat Island Effect Analysis: Comparing Land Surface Temperatures Between Built-Up and Green Areas Using Satellite Data

Abstract

The Urban Heat Island (UHI) effect is a phenomenon wherein urban areas record significantly higher land surface temperatures (LST) than surrounding rural or vegetated regions, primarily as a result of anthropogenic land use modifications. This study analyzes the UHI effect in the New Town area of Kolkata, West Bengal, India, by comparing LST values between the Eco Park green zone and adjacent built-up concrete areas. Satellite imagery sourced from the United States Geological Survey (USGS) Earth Explorer platform was processed using ArcGIS zonal statistics tools. Results derived from four delineated zones reveal the mean temperatures and the temperatures are 19.47°C,19.73°C,21.32°C and 20.67°C. Disaggregated zone-level data indicate that built-up areas exhibit measurably higher LST values relative to the green zone dominated by Eco Park\'s vegetation and water bodies. These findings affirm the thermal amelioration potential of urban green infrastructure and underscore the importance of integrating vegetation cover in city planning to mitigate the adverse effects of UHI. The study contributes to a growing body of evidence supporting evidence-based urban heat management strategies in rapidly urbanizing Indian cities.

Introduction

This study investigates the Urban Heat Island (UHI) effect in New Town, Kolkata, focusing on the thermal contrast between Eco Park, a large urban green space, and the surrounding built-up urban environment. Rapid urbanization has replaced natural vegetation and wetlands with concrete infrastructure, increasing land surface temperatures (LST) and intensifying urban heat. Eco Park serves as an ecological buffer and provides an opportunity to evaluate the cooling benefits of urban green infrastructure.

Using Landsat 8/9 satellite imagery obtained from the USGS and processed in ArcGIS Pro, the study extracted and mapped Land Surface Temperature (LST) values. The area was divided into four zones: Eco Park, surrounding green areas, and two built-up urban zones. GIS-based zonal statistics were applied to compare average temperatures and quantify UHI intensity.

The literature review highlights that urban heat islands are primarily caused by impervious surfaces, reduced vegetation, decreased evapotranspiration, and increased heat storage in buildings. Previous studies have shown that urban parks act as “cool islands,” reducing surrounding temperatures through shading and evapotranspiration. Remote sensing techniques such as Landsat-derived LST and NDVI analysis are widely used for monitoring these thermal variations.

The methodology involved converting satellite thermal data into surface temperatures through radiometric calibration, brightness temperature estimation, emissivity correction using NDVI, and final LST calculation. UHI intensity was measured by comparing urban temperatures with those of green areas.

Results revealed clear thermal differences among the zones:

The findings show that Eco Park is approximately 1.85°C cooler than the hottest built-up zone, confirming its significant cooling effect. Vegetated areas consistently exhibited lower temperatures than surrounding urban surfaces, demonstrating the role of green spaces in mitigating UHI impacts.

Conclusion

This study successfully demonstrates the presence of the Urban Heat Island effect in the New Town (Rajarhat) area of Kolkata, West Bengal, using USGS satellite-derived Land Surface Temperature data and ArcGIS zonal statistics. The results confirm that built-up areas within the study zone exhibit higher mean LST values compared to the Eco Park green zone, with Zone 3 (densely built-up) recording 21.32°C against Eco Park\'s 19.47°C — a thermally significant difference considering these are spatially averaged zonal means. The findings highlight the invaluable role of Eco Park as an urban thermal refuge in an otherwise rapidly concretizing urban environment. Water bodies, tree cover, and managed vegetation collectively contribute to measurable surface cooling, illustrating the ecosystem service value of urban green spaces in mitigating UHI. From an urban planning perspective, this study advocates for the strategic expansion and preservation of green spaces in Indian metropolitan cities. As Kolkata and similar rapidly urbanizing centres continue togrow, incorporating UHI mitigation strategies — including urban parks, green corridors, rooftop gardens, and tree-lined streets — into master planning frameworks is imperative. Future research should extend this analysis to include multi-temporal satellite data, NDVI-LST regression modelling, atmospheric correction validation, and socio-economic vulnerability mapping to assess which urban populations are most exposed to heat stress. Such integrated approaches will strengthen the scientific foundation for heat-resilient urban planning policies in South Asia.

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