The Diversified Impacts of Urban Morphology on Land Surface Temperature among Urban Functional Zones.

Sihang Gao,Qingming Zhan,Huimin Liu,Chen Yang

doi:10.3390/ijerph17249578

Abstract

Local warming induced by rapid urbanization has been threatening residents’ health, raising significant concerns among urban planners. Local climate zone (LCZ), a widely accepted approach to reclassify the urban area, which is helpful to propose planning strategies for mitigating local warming, has been well documented in recent years. Based on the LCZ framework, many scholars have carried out diversified extensions in urban zoning research in recent years, in which urban functional zone (UFZ) is a typical perspective because it directly takes into account the impacts of human activities. UFZs, widely used in urban planning and management, were chosen as the basic unit of this study to explore the spatial heterogeneity in the relationship between landscape composition, urban morphology, urban functions, and land surface temperature (LST). Global regression including ordinary least square regression (OLS) and random forest regression (RF) were used to model the landscape-LST correlations to screen indicators to participate in following spatial regression. The spatial regression including semi-parametric geographically weighted regression (SGWR) and multiscale geographically weighted regression (MGWR) were applied to investigate the spatial heterogeneity in landscape-LST among different types of UFZ and within each UFZ. Urban two-dimensional (2D) morphology indicators including building density (BD); three-dimensional (3D) morphology indicators including building height (BH), building volume density (BVD), and sky view factor (SVF); and other indicators including albedo and normalized difference vegetation index (NDVI) and impervious surface fraction (ISF) were used as potential landscape drivers for LST. The results show significant spatial heterogeneity in the Landscape-LST relationship across UFZs, but the spatial heterogeneity is not obvious within specific UFZs. The significant impact of urban morphology on LST was observed in six types of UFZs representing urban built up areas including Residential (R), Urban village (UV), Administration and Public Services (APS), Commercial and Business Facilities (CBF), Industrial and Manufacturing (IM), and Logistics and Warehouse (LW). Specifically, a significant correlation between urban 3D morphology indicators and LST in CBF was discovered. Based on the results, we propose different planning strategies to settle the local warming problems for each UFZ. In general, this research reveals UFZs to be an appropriate operational scale for analyzing LST on an urban scale.

Highlights

Changes in urban function and urban form have collectively modified the urban heat balance, resulting in local warming at the intra-urban scale, which has raised significant concerns among urban researchers [1,2]
According to statistics, the maximum Land surface temperature (LST) is concentrated in Industrial and Manufacturing (IM) (48.88 ◦ C) and Logistics and Warehouse (LW) (48.70 ◦ C) and the minimum LST is concentrated in Green Space (GS) (43.80 ◦ C) and W (41.61 ◦ C)
In Vacant Land (VL) and Road and Transportation (RT), there is a low correlation between the selected indicators and LST in the global regression, so the spatial heterogeneity in the Landscape-LST relationship in these two types of urban functional zone (UFZ) will not be further discussed in subsequent studies

Summary

Introduction

Changes in urban function and urban form have collectively modified the urban heat balance, resulting in local warming at the intra-urban scale, which has raised significant concerns among urban researchers [1,2]. Accompanying alteration in the surface three-dimensional morphology impedes ventilation [7,8]. These combined effects increase the difficulties in heat exchange between urban areas and the surrounding environment [9]. The correlation between LST and urban characteristics such as impervious surface fraction, vegetation indexes, and building indexes has been well documented at the intra-urban scale, facilitating the translation of interaction knowledge between the physical form and the climatic context into practical planning applications [12,13,14,15]. This study aims to convey further knowledge about how LST is impacted by potential landscape drivers [16]

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Conclusion