Land Surface Temperature and Land Cover in Valencia with Landsat 9 ^†

Cities, home to 56% of the world’s population, face increasing challenges due to climate change and rapid urbanization, with a projected urban sprawl of 1.2 million km² by 2030 [1]. These processes intensify environmental impacts, such as the formation of Urban Heat Islands (UHIs), where temperatures are higher than in rural areas due to the loss of vegetation and the use of heat-retaining surface materials [2]. Valencia, the city studied herein, is already experiencing these effects: there has been a 1 °C increase in its average annual temperature relative to that in 1960, and a record 46.8 °C was recorded in 2023 [3,4].

Several studies have shown that the distribution of UHIs is not always concentric; it depends on land use, vegetation cover, urban morphological conditions, and human activity. Cases in cities such as Tabriz, Delhi, and San Salvador show how industrial areas, dense residential areas, and seasonal variations influence surface temperatures [5,6,7].

In this study, we aim to identify and map UHIs in Valencia using satellite imagery, analyzing the influence of urban morphology and land cover on surface temperature to support mitigation strategies.

The methodology was based on an analysis of Landsat 9 satellite imagery (2020–2024) in which Google Earth Engine was used to calculate the average surface temperature during the heatwave alert period (15 May to 30 September). This information was integrated with land cover mapping (COSCV) to assess its influence on the thermal distribution. Statistical tests were applied to analyze the relationships between temperature and land cover. The open-source code developed by [8] was used to generate heat island maps with 30 m resolution.

The results show that surface temperature is closely related to the type and proportion of land cover as well as to its spatial distribution. The observed thermal patterns remain constant over time, with lower temperatures being recorded in areas with vegetation, water bodies, and infrastructure, while densely built-up areas and sports areas show significantly higher temperatures.

These findings indicate that land cover is a determining factor in ICU development. We recommend enlarging green areas, applying nature-based solutions in industrial and sports spaces, and improving land classification for future research by better differentiating between different urban typologies.