Combined Effects of Artificial Surface and Urban Blue-Green Space on Land Surface Temperature in 28 Major Cities in China

Liang Chen,Xiaorong Lu,Xiaobin Cai,Xuelei Wang,Chao Yang

doi:10.3390/rs14030448

Liang Chen, Xiaorong Lu + Show 3 more

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https://doi.org/10.3390/rs14030448

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Abstract

The two most common land cover types in urban areas, artificial surface (AS) and urban blue-green space (UBGS), interact with land surface temperature (LST) and exhibit competitive effects, namely, heating and cooling effects. Understanding the variation of these effects along the AS ratio gradient is highly important for the healthy development of cities. In this study, we aimed to find the critical point of the joint competitive effects of UBGS and AS on LST, and to explore the variability in different climate zones and cities at different development levels. An urban land cover map and LST distribution map were produced using Sentinel-2 images and Landsat-8 LST data, respectively, covering 28 major cities in China. On this basis, the characteristics of water, vegetation, and LST in these cities were analyzed. Moreover, the UBGS (water or vegetation)–AS–LST relationship of each city was quantitatively explored. The results showed that UBGS and AS have a competitive relationship and jointly affect LST; this competition has a critical point (threshold). When the proportion of UBGS exceeds this value, UBGS replaces AS as the dominant variable for LST, bringing about a cooling effect. In contrast, when AS dominates LST, it causes a warming effect. The critical points between AS and water and between AS and vegetation in 28 major cities in China were 80% and 70%, respectively. The critical point showed an obvious zonal difference. Compared with cities in subtropical and temperate climate regions, the critical point of arid cities is higher, and UBGS exhibited better performance at alleviating the urban thermal environment. The critical point of cities with higher development levels is lower than that of cities with lower development levels. Even areas with relatively low AS coverage are prone to high temperatures, and more attention should be paid to improving the coverage of UBGS. Our research results provide a reference for the more reasonable handling of the relationship between urban construction, landscape layout, and temperature control.

Highlights

Introduction published maps and institutional affilOngoing rapid urbanization has led to the evolution of urban landscape patterns and processes [1,2,3,4,5], resulting in changes in the types of urban surface cover, which in turn has led to changes in the thermodynamic properties of urban surfaces, and given rise to the urban heat island (UHI) effect and other ecological consequences [6,7,8,9]
Characteristics of the artificial surface (AS), urban blue-green space (UBGS), and land surface temperature (LST) within the 28 Major Urban Areas in China values of 28 major cities in China were calculated on the urban scale, and the results were further counted according to the climate zone and development level (Figure 4)
The overall proportion of AS, water, and vegetation in these urban areas ranged from 44.99% (Harfurther counted according to the climate zone and development level (Figure 4)

Summary

Introduction

Ongoing rapid urbanization has led to the evolution of urban landscape patterns and processes [1,2,3,4,5], resulting in changes in the types of urban surface cover, which in turn has led to changes in the thermodynamic properties of urban surfaces, and given rise to the urban heat island (UHI) effect and other ecological consequences [6,7,8,9]. The UHI effect introduces a series of hazards to the urban climate and to residents’. Finding a method to alleviate the high temperatures of urban summer has become a current research hotspot in multi-disciplinary fields, such as urban thermal environmental effects, climate change, and urban natural disasters [21,22,23,24]. Finding a method to alleviate the high temperatures of urban summer has become a current research hotspot in multi-disciplinary fields, such as urban thermal environmental effects, climate change, and urban natural disasters [21,22,23,24]. iations.

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