Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data

Urban Heat Islands (UHI) represent an increasing challenge in cities worldwide, including smaller urban centres such as Varaždin, Croatia. This study analyses UHI dynamics over a Varaždin city during a ten-year period (2014–2024) using exclusively Free and Open-Source Software (FOSS) and p...

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Main Authors: S. Šamanović, O. Bjelotomić Oršulić, T. Krajina, D. Markovinović
Format: Article
Language:English
Published: Copernicus Publications 2025-07-01
Series:The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Online Access:https://isprs-archives.copernicus.org/articles/XLVIII-4-W13-2025/217/2025/isprs-archives-XLVIII-4-W13-2025-217-2025.pdf
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author S. Šamanović
O. Bjelotomić Oršulić
T. Krajina
D. Markovinović
author_facet S. Šamanović
O. Bjelotomić Oršulić
T. Krajina
D. Markovinović
author_sort S. Šamanović
collection DOAJ
description Urban Heat Islands (UHI) represent an increasing challenge in cities worldwide, including smaller urban centres such as Varaždin, Croatia. This study analyses UHI dynamics over a Varaždin city during a ten-year period (2014–2024) using exclusively Free and Open-Source Software (FOSS) and publicly available Earth Observation (EO) data. Landsat 8 thermal imagery was used to calculate Land Surface Temperature (LST), and to analyse its relationship with vegetation cover through the Normalized Difference Vegetation Index (NDVI) and the Proportion of Vegetation (PV). Urban expansion was examined using the Normalized Difference Built-up Index (NDBI). All indices were derived from multispectral and thermal bands using QGIS 3.24 and Python 3.12 libraries including GDAL, rasterio, NumPy, and Matplotlib. The results show a measurable increase in surface temperature, with the average LST rising by +4.41 °C, accompanied by a loss of 3,230 pixels in the dense vegetation class (NDVI > 0.4). Simultaneously, NDBI values indicate expansion of built-up areas across the southern and eastern parts of the city. These changes confirm the spatial transformation towards the urbanization and reduced vegetation cover as main cause of local thermal intensification. This study gives a standardized, open-sourced, transparent and reproducible analysis applicable to other medium-sized cities. The study also explores the potential integration of additional EO sources (Sentinel-3, MODIS, VIIRS) and supporting geospatial data (OpenStreetMap) for enhanced spatiotemporal resolution. The findings highlight the value of FOSS tools and open data in supporting evidence-based urban climate planning and advocate for scalable, cost-effective approaches to UHI mitigation through green infrastructure and adaptive design.
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spelling doaj-art-9f9951568a964d4380fa40258aa44a792025-08-20T03:28:26ZengCopernicus PublicationsThe International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences1682-17502194-90342025-07-01XLVIII-4-W13-202521722410.5194/isprs-archives-XLVIII-4-W13-2025-217-2025Tracking Urban Heat Island Dynamics Using Open Source Tools and Free DataS. Šamanović0O. Bjelotomić Oršulić1T. Krajina2D. Markovinović3Department of Geodesy and Geomatics, University North, 42000 Varaždin, CroatiaDepartment of Geodesy and Geomatics, University North, 42000 Varaždin, CroatiaDepartment of Geodesy and Geomatics, University North, 42000 Varaždin, CroatiaDepartment of Geodesy and Geomatics, University North, 42000 Varaždin, CroatiaUrban Heat Islands (UHI) represent an increasing challenge in cities worldwide, including smaller urban centres such as Varaždin, Croatia. This study analyses UHI dynamics over a Varaždin city during a ten-year period (2014–2024) using exclusively Free and Open-Source Software (FOSS) and publicly available Earth Observation (EO) data. Landsat 8 thermal imagery was used to calculate Land Surface Temperature (LST), and to analyse its relationship with vegetation cover through the Normalized Difference Vegetation Index (NDVI) and the Proportion of Vegetation (PV). Urban expansion was examined using the Normalized Difference Built-up Index (NDBI). All indices were derived from multispectral and thermal bands using QGIS 3.24 and Python 3.12 libraries including GDAL, rasterio, NumPy, and Matplotlib. The results show a measurable increase in surface temperature, with the average LST rising by +4.41 °C, accompanied by a loss of 3,230 pixels in the dense vegetation class (NDVI > 0.4). Simultaneously, NDBI values indicate expansion of built-up areas across the southern and eastern parts of the city. These changes confirm the spatial transformation towards the urbanization and reduced vegetation cover as main cause of local thermal intensification. This study gives a standardized, open-sourced, transparent and reproducible analysis applicable to other medium-sized cities. The study also explores the potential integration of additional EO sources (Sentinel-3, MODIS, VIIRS) and supporting geospatial data (OpenStreetMap) for enhanced spatiotemporal resolution. The findings highlight the value of FOSS tools and open data in supporting evidence-based urban climate planning and advocate for scalable, cost-effective approaches to UHI mitigation through green infrastructure and adaptive design.https://isprs-archives.copernicus.org/articles/XLVIII-4-W13-2025/217/2025/isprs-archives-XLVIII-4-W13-2025-217-2025.pdf
spellingShingle S. Šamanović
O. Bjelotomić Oršulić
T. Krajina
D. Markovinović
Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
title Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
title_full Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
title_fullStr Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
title_full_unstemmed Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
title_short Tracking Urban Heat Island Dynamics Using Open Source Tools and Free Data
title_sort tracking urban heat island dynamics using open source tools and free data
url https://isprs-archives.copernicus.org/articles/XLVIII-4-W13-2025/217/2025/isprs-archives-XLVIII-4-W13-2025-217-2025.pdf
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