The study explores the relationship between urban morphology and land surface temperature (LST) using ECOSTRESS sensor data to understand the factors influencing urban overheating. This research highlights the significant impact urban design has on the thermal comfort and livability of cities, especially as climate change accelerates the occurrence of extreme heat.
Urban overheating, exacerbated by climate change and rapid urbanization, has gained attention due to its adverse effects on public health and energy consumption. According to projections from the United Nations, approximately 70% of the global population will reside in urban areas by 2050, up from 54% just ten years earlier. The transformation of urban landscapes can significantly influence local climates, leading to what is known as the urban heat island effect (UHI), wherein urban areas experience markedly higher temperatures than their surrounding rural areas.
A comprehensive investigation conducted by researchers L. Ding, X. Xiao, and H. Wang, outlines how three-dimensional characteristics of urban morphology influence LST across various seasons and times of day. The study, released recently, utilizes ECOSTRESS satellite data to draw correlations between factors such as building density, mean building height, building volume, and other urban form factors with land surface temperatures.
The research identifies and analyzes six key urban morphology variables: building density (BD), mean building height (MH), building volume (BVD), gross floor area (GFA), floor area ratio (FAR), and sky view factor (SVF). Through four different machine learning models, the study aims to quantify the interaction of these urban characteristics with seasonal and diurnal temperature variations.
One of the most significant findings indicates the stable influence of mean building height, building density, and floor area ratio on LST, showing how higher buildings correlate with lower temperatures—observing reductions of up to approximately 3 °C during spring. Conversely, higher building density was associated with increased land surface temperatures—increases of about 3.5 °C recorded during autumn. This variability highlights the stark differences between seasonal effects on urban thermal dynamics.
Building volume, gross floor area, and sky view factor exhibited variable impacts contingent on the season. For example, building volume tends to correlate with higher surface temperatures, indicating the need for careful urban planning to manage architectural designs and densities. Meanwhile, floor area ratio is linked to lower LSTs, reflecting how different urban layouts can mitigate heat absorption.
The researchers utilized high-quality data from the NASA-built ECOSTRESS system, which provides detailed insights on land surface temperatures at various times. Conducted over the period from July to October of 2018 to 2022, the study carefully selected cloud-free imagery to maximize data accuracy for various city blocks within Shijiazhuang, Hebei Province. This approach allowed for the examination of how urban design elements function within distinct microclimates.
Results pointed out the relevance of three-dimensional urban forms—where building height and density directly influence temperatures experienced at ground level. According to the authors, "the increasing importance of the urban thermal environments to human well-being has become a matter of public concern."
The integrated use of advanced machine learning models facilitated rigorous analyses, delineation of patterns, and the identification of correlation curves necessary for predictive urban heat modeling.
Importantly, seasonally stable factors identified, including building height, underscored the pressing need for urban redevelopment practices to lean toward sustainable planning methods aimed at reducing UHI effects. Strong correlations observed between the spatial dimensions of buildings and LST allow for decisive actions toward enhancing urban livability through improved architectural regulations.
These findings offer valuable insights, helping to inform strategies for urban heat mitigation and sustainable planning. The results propose significant modifications necessary to urban regulations, enhancing our ability to combat rising temperatures linked to extensive urbanization.
To conclude, this research shed light on how urban architectural forms influence land surface temperatures across seasons, laying the groundwork for future urban planning efforts aimed at improving human comfort and environmental sustainability.