Influence of the Mega-Urban Heat Island on Spatial Transfer of Summer Thermal Comfort: Evidence from Tianjin, China

Abstract

Human thermal comfort in urban spaces deteriorates as rapid urbanization proceeds. However, effective tests and discoveries of spatial statistic patterns are currently absent. This study collected remote sensing images and measured meteorological data of the summers of 1992-2017, Tianjin of China and aims to clarify patterns of spatial transfer and thermal comfort changes caused by a mega-UHI (Urban Heat Island). An analytic transfer matrix and the spatial autocorrelation were developed to study spatial pattern changes and features of the spatial transfer of thermal comfort caused by UHI. Results show these patterns in the affected areas can be divided into different levels: patterns of low-level affected areas transferred by circular expansion into block-mass jumping, while the position of high-level affected areas remains stable. The spatial transfer of thermal comfort in the affected areas shows two apparent stages: the transfer from areas of high-density and low-storied buildings and into areas of multiple storied buildings, and transfer from areas of low and multiple storied buildings into those of high storied buildings. This implies changes in urban planning can guide spatial, structural, and functional evolution. The study identifies features of spatial change and spatial patterns related to the influence of Mega-UHI on thermal comfort.

Spatial Evolution of the Effects of Urban Heat Island on Residents' Health

“…In extreme cases, heat exposure causes death and various diseases of the respiratory, urinary, circulatory, and nervous systems [23]. The characteristics of the spatial pattern of UHI on human physiology and comfort [8] and the mechanism of the UHI on respiratory diseases [9] on the basis of the human body's physiological response to high temperatures were explored by Huang. However, these studies focused only on single factors, such as physiological comfort or respiratory diseases, and rarely involved a comprehensive study of the physical and mental health hazards caused by UHI and the risk characteristics of their spatial patterns.…”

“…However, most studies focused on the evolution of UHI in different urban spaces rather than on the spatiotemporal response mechanism of UHI on urban residents' health. Only a few studies examined the effects of UHI in megacities on the typical spatial and temporal patterns of human comfort [8] and respiratory diseases [9]. Given that these studies focused on single factors, such as physiological comfort or respiratory diseases, they lack representative space research on diseases or the comprehensive health hazards of UHI on physical and psychological aspects and cannot assess the health risks of different spatial locations in cities.…”