Complexity of the relationship between 2D/3D urban morphology and the land surface temperature: a multiscale perspective.

Yu Liu,Zhipeng Wang,Xuan Liu,Baolei Zhang

doi:10.1007/s11356-021-15177-7

Abstract

Urban morphology is a crucial contributor to urban heat island (UHI) effects. However, few studies have explored the complex effect of 2D/3D urban morphology on UHIs from a multiscale perspective. In this study, we chose the central area of Jinan city, which is commonly known as the "furnace," as the case study area. The 2D/3D urban morphology indexes-building coverage ratio (BCR) (for assessing the 2D building density), building volume density (BVD) (for assessing the 3D building density), and frontal area index (FAI) (for assessing 3D ventilation conditions) were calculated and derived to investigate the complexity of the relationship between 2D/3D urban morphology and the land surface temperature (LST) at different scales using the maximum information coefficient (MIC) and geographically weighted regression (GWR). The results indicated that (1) these 2D/3D urban morphology indexes are essential factors that are responsible for LST variation, and BCR is the most important urban morphology index affecting LST, followed by BVD and FAI. Importantly, the relationship between the BCR, BVD, FAI, and LST was an inverse U-shaped curve. (2) The relationship between 2D/3D urban morphology and LST variation showed a significant scale effect. With increased grid size, the correlation between the BCR, BVD, and FAI and the LST strengthened, "inflection point" of inverse U-shaped curve significantly declined, and their explanation rate of the LST first increased and then decreased, with a maximum value at the 700 m scale. Additionally, the FAI exerted a stronger negative effect, while the BCR and BVD generally had stronger positive effects on the LST as the grid size increased. This study extends our scientific understanding of the complex effect of urban morphology on the LST and is of great practical significance for multiscale urban thermal environment regulation.

Highlights

In recent decades, the world has experienced explosive population growth and urban sprawl (Seto et al 2012)
To enhance our understanding of the effects of 2D/3D urban morphology on land surface temperature (LST), this study established a multiscale analysis of the effects of 2D/3D urban morphology on LST in the central urban districts of Jinan city using the maximum information coefficient (MIC) and geographically weighted regression (GWR) methods
The building coverage ratio (BCR) had a stronger association with LST variation than did building volume density (BVD) and frontal area index (FAI), and the relationship between the BCR, BVD, and FAI and the LST was an inverse U-shaped curve, implying that the BCR, BVD and FAI positively impacted LST at a certain level

Summary

Introduction

The world has experienced explosive population growth and urban sprawl (Seto et al 2012). The topic of the urban thermal environment has raised significant concerns among many related research fields (Wang et al 2020, Yu et al 2019). The UHI effect can be assessed by either air temperature or land surface temperature (LST), in which LST is considered to correspond closely with the canopy layer UHI and has been widely used in studying the surface UHI (SUHI) effect (Weng 2009). It is largely recognized that satellite-based remote sensing techniques are able to provide spatially continuous coverage of LST in a time- and cost-efficient manner (Huang &Wang 2019a), and these techniques can provide urban morphology information (e.g., urban structure types, landscape patterns, settlement density). LST has been widely used to investigate the relations between the SUHI effect and urban morphology indicators (e.g., land-cover/use types, landscape patterns) (Carmona et al 2017, Zhou et al 2017)

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