Document Type : Research Article
Authors
1
Department of Geography and Urban Planning, Faculty of Humanities, Maragheh University, Maragheh, Iran
2
Department of Remote Sensing and GIS, Faculty of Planning and Environmental Sciences, University of Tabriz, Tabriz, Iran
Abstract
Urban heat islands (UHIs) are an environmental challenge in developing cities such as Mosul, intensified by the reduction of vegetation cover and the increase of impervious surfaces. This study, has employed Landsat 9, MODIS, and Sentinel-2A imagery along with object-based processing, examined the role of land use changes and surface characteristics in the formation of Mosul’s SUHI in 2024. The findings indicated that vegetation cover has the greatest cooling effect, showing a strong negative correlation with surface temperature (r = -0.833), while built-up areas, represented by NDBI and SI indices, exhibit a positive correlation with temperature. Areas with vegetation were up to 5.6°C cooler than densely urbanized areas. The greatest contribution to the intensification of heat islands comes from built-up areas, whereas green spaces and agricultural lands play a significant role in temperature reduction. Cooling effects of green patches are stronger during the day than at night. In summer, SUHI intensity increased, with the highest temperatures reaching up to 43°C in peripheral areas, while the city center retained more heat at night. The GSCEI index confirmed a reduction of up to 2.5°C in the vicinity of green patches. The uneven distribution of green spaces and surface characteristics plays a fundamental role in the intensity and extent of SUHI.
Introduction
Urban expansion and the reduction of green spaces are among the principal drivers of surface urban heat islands (SUHIs) a phenomenon that has become a major challenge in contemporary cities, particularly in arid and semi-arid regions. The intensification of SUHIs not only affects local climate conditions but also influences energy consumption, public health, and overall urban sustainability. Increasing urban temperatures can exacerbate heat stress, elevate air conditioning demands, and contribute to poor air quality. This study aims to examine the influence of green patches and surface biophysical characteristics on UHI patterns in the city of Mosul. By integrating multiple remote sensing datasets with GIS-based spatial analyses, the research provides a comprehensive and detailed assessment of the spatio-temporal patterns of land surface temperature (LST) and its relationships with various biophysical indices. Furthermore, this study seeks to identify critical areas where targeted interventions, such as the expansion of green spaces or modification of surface materials, can effectively mitigate SUHI effects.
Material and Methods
To assess the effects of the spatial distribution of urban green patches and surface biophysical properties on SUHI patterns, we first used meteorological data from the Mosul synoptic station to identify the city’s minimum and maximum temperature periods. This approach allowed us to focus on the most thermally sensitive periods and provided a reliable baseline for LST comparisons. We then acquired time-matched satellite imagery Sentinel-2A, Landsat-9, and MODIS from 2024 covering both daytime and nighttime windows in summer and winter. After rigorous preprocessing, including atmospheric correction, radiometric calibration, and geometric alignment, the images were classified to differentiate between impervious surfaces, vegetation, water bodies, and other land cover types. SUHIs across Mosul were subsequently identified using standard LST extraction methods and validated with ground-based observations where available. LST outputs were overlaid with green-patch layers and additional biophysical variables, including vegetation cover, surface type, soil moisture, buildings, and surface water. Their correlations with LST were computed to elucidate the spatial distribution and intensity of heat islands in various urban contexts. ArcGIS, eCognition Developer, ENVI 5.3 and Microsoft Excel were employed for image processing, classification and statistical analyses, ensuring a rigorous and reproducible workflow.
Results and Discussion
Both the present study and prior international research emphasize the importance of appropriately distributing green spaces and managing impervious surfaces to mitigate thermal impacts and improve residents’ quality of life. Our findings show that the NDVI averages 0.78 in areas with greater vegetation cover and decreases to 0.45 in impervious areas; this inverse relationship between NDVI and temperature is reflected in a strong negative correlation (R = −0.833), clearly indicating the cooling effect of vegetation on surface temperatures. In addition, analysis of LST in four-time windows (daytime and nighttime in summer, and daytime and nighttime in winter) demonstrates a significant influence of land use on the spatial distribution of surface heat in Mosul. In summer, industrial and commercial land uses especially industrial zones with daytime LST of 38.199 °C and nighttime LST of 43.007 °C contribute most to elevated surface temperatures, likely due to the high density of heat-absorbing construction materials, scarcity of vegetation, and heat-generating activities. Dense commercial and residential areas also play a substantial role in increasing LST because of compact urban form, extensive asphalt coverage, and heavy vehicular traffic. The temporal analysis further shows that daytime LST peaks are closely associated with solar radiation exposure, while nighttime temperatures remain elevated in densely built areas due to the thermal retention of construction materials, a phenomenon often referred to as the “urban heat storage effect.” The spatial patterns of LST also reveal that peripheral districts with scattered vegetation exhibit slightly lower temperatures, indicating that strategic placement of green patches can create meaningful thermal refuges even in predominantly urbanized settings.
Conclusion
The results indicate that the uneven distribution of green spaces and the expansion of impervious surfaces are key drivers of SUHI intensification in Mosul. Surface biophysical characteristics, particularly in areas with limited vegetation, exert a marked effect on increasing temperatures and amplifying SUHI formation. The study underscores the critical role of green-patch distribution and biophysical attributes in shaping LST and UHI patterns in Mosul. These findings can inform management strategies aimed at moderating UHI effects and improving urban environmental conditions. Future urban planning should prioritize developing a connected network of green spaces, especially in central districts; employing high-albedo construction materials; and implementing green roofs and green walls in high-density areas. Such measures can reduce urban ambient temperatures, enhance residents’ thermal comfort, and improve overall quality of life. Furthermore, incorporating green infrastructure into urban design can simultaneously provide ecological benefits, such as improved stormwater management, air purification, and biodiversity conservation, thereby creating more resilient and sustainable cities. By combining these approaches with continuous monitoring using remote sensing and GIS, city planners can develop evidence-based strategies to mitigate SUHI impacts and support long-term urban sustainability goals.
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