Spatiotemporal Patterns and Drivers of the Surface Urban Heat Island in 36 Major Cities in China: A Comparison of Two Different Methods for Delineating Rural Areas

Lu Niu,Ronglin Tang,Yazhen Jiang,Xiaoming Zhou

doi:10.3390/su12020478

Abstract

Urban heat islands (UHIs) are an important issue in urban sustainability, and the standardized calculation of surface urban heat island (SUHI) intensity has been a common concern of researchers in the past. In this study, we used the administrative borders (AB) method and an optimized simplified urban-extent (OSUE) algorithm to calculate the surface urban heat island intensity from 2001 to 2017 for 36 major cities in mainland China by using Moderate Resolution Imaging Spectroradiometer (MODIS) images. The spatiotemporal differences between these two methods were analyzed from the perspectives of the regional and national patterns and the daily, monthly, and annual trends. Regardless of the spatial or temporal scale, the calculation results of these two methods showed extremely similar patterns, especially for the daytime. However, when the calculated SUHI intensities were investigated through a regression analysis with multiple driving factors, we found that, although natural conditions were the main drivers for both methods, the anthropogenic factors obtained from statistical data (population and gross domestic product) were more correlated with the SUHI intensity from the AB method. This trend was probably caused by the spatial extent of the statistical data, which aligned more closely with the rural extent in the AB method. This study not only explores the standardization of the calculation of urban heat intensity but also provides insights into the relationship between urban development and the SUHI.

Highlights

In 2014, over 54% of people in the world lived in densely populated urban areas, and it is expected that the global urban population will increase to 66% of the total population by 2050 [1]
In this study, we described the daytime and nighttime surface urban heat island (SUHI) in 36 major cities in China (Figures 3 and 4), from 2001 to 2017, for these three conditions to understand the national distribution pattern of SUHI. (As Guangdong and Shenzhen have a high urbanization level and the distribution is centralized, they have been defined as one city in the optimized simplified urban-extent (OSUE) method; there are 35 cities in Figure 4.) The daytime and nighttime intensities were consolidated values from the Terra and
The administrative borders (AB) and OSUE methods identified the proportions of SUHI intensity with positive values at 86% and 94%, respectively

Summary

Introduction

In 2014, over 54% of people in the world lived in densely populated urban areas, and it is expected that the global urban population will increase to 66% of the total population by 2050 [1]. Rapid urbanization is one of the most important human influences on the atmosphere and causes obvious disruptions of atmospheric energy [2,3]. The most widely known consequence of these influences is the generation of the urban heat island effect. There is ample evidence that when these effects interact with global changes, the intensity of the impact is further increased [9]

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Results

Discussion

Conclusion