An investigation into urban heat mitigation by adopting local climate zones and land surface temperatures in the Tokyo prefecture

Abstract

This study aimed to investigate urban forms susceptible to heightened heat intensities in the Tokyo Prefecture in Japan. Adopting Landsat 8 data at a pixel resolution of 100 m, local climate zones (LCZ) were identified. LCZs contain urban forms which are primarily defined by building compactness and height. Daytime spatial distribution of land surface temperatures (LST) was provided by MODIS 100 m resolution data from 2013 to 2021. Median LSTs for compact and super high‐rise, high‐rise, mid‐rise, and low‐rise LCZs were 34.4, 35.5, 37.3, and 38.1°C, respectively. Additionally, LSTs for open and super high‐rise, high‐rise, and mid‐rise LCZs were 37.4, 37.5, and 37.1°C, respectively. Therefore, this suggests lower‐rise and open LCZs are prone to increased urban heat intensities and higher‐rise and compact LCZs are an urban heat mitigation strategy. Open mid‐rise also offers heat reduction capabilities. Compact low‐rise and open mid‐rise spatial analysis also confirmed this trend with vegetation indices validating urban configuration as significantly influencing LSTs. Furthermore, due to LSTs constituting heat health risks, 11 municipalities comprised of predominantly compact low‐rise LCZs were identified as a priority for urban heat mitigation. Among these, Nakano, Nerima, and Suginami posed the greatest heat risks.

Effective Factors for Reducing Land Surface Temperature in Each Local Climate Zone Built Type in Tokyo and Shanghai

“…Heavy industry type had some overlapped ranges with open mid-rise type and open low-rise type. Through GEP, it was found that the heavy industry type exists only in the areas neighboring Tokyo, such as Kawasaki, Yokohama, and Chiba, but not in Tokyo itself, which is consistent with previous studies [86,98]; hence, heavy industry type was not defined in Tokyo in this study.…”

“…LCZ land cover types were defined through the description of each LCZ land cover type (Figure A1) and satellite images in GEP. Bush & scrub type (LCZ C) and bare soil or sand type (LCZ F) were not found in Tokyo, consistent with the previous study [86,98], so they were not defined in Tokyo. Dense trees type (LCZ A) and shrubs & bushes type (LCZ C) were located outside the administrative boundaries of Shanghai [99], so they were not defined in Shanghai.…”

“…As megacities with high urbanization, Tokyo and Shanghai suffer from severe UHIs [78,85,86] and extreme heat events [87] during summer. Tokyo experienced a series of heatwaves in 2010, and the number of heat stroke patients soared to about six times that of previous years; since 2010, the number of heat stroke patients has continued to rise [16].…”