Trend Analysis of Urban Heat Island Intensity According to Urban Area Change in Asian Mega Cities

Abstract

Urban heat island (UHI) is a phenomenon that occurs in cities worldwide. Therefore, there is an increasing need for studies on the changes in UHI intensity and long-term trends based on macroscopic characteristics related to urbanization. In this study, changes in seasonal UHI intensity based on urban area were analyzed for eight Asian mega cities from 1992-2012. The results indicate that the change in pattern of UHI intensity varies for different cities and seasons. UHI intensity increased as the urban area size increased. Furthermore, the dependency of UHI intensity on the economic situation was also demonstrated. With respect to the seasons, significantly increasing trends appeared during the summer. Moreover, depending on urban characteristics such as geography and climate, increasing trends appeared during other seasons. Population was also found to affect UHI intensity by generating anthropogenic heat; however, its effect as an individual factor appeared to be insignificant. This is a macroscale study that analyzes the effect of urban area size on UHI intensity. Future studies on urbanization factors and levels influencing the UHI intensity using higher resolution materials are required Sustainability 2020, 12, 112 2 of 11 characteristics or fundamental differences among them. The number of systematic empirical studies of the latter type has increased because of the accessibility of remote sensing with global coverage [9], and our study falls into this category. Several studies have indicated that continuing urbanization progressively increases the UHI intensity, and several others have demonstrated that the urban impact could have an effect on recent warming trends [10][11][12]. Hence, comparative studies on UHI changes for cities with different climatic and socio-economic situations, and on urban characteristics, are essential for researchers and decision-makers [6,[13][14][15][16].Several existing studies that focus on UHI at a macroscopic level were examined. Karl et al.[17] classified urbanization in cities of the United States based on population, and performed a time-series analysis for each season. The UHI intensity was defined as the temperature differences between urban and suburban areas with regard to the degree of urbanization. This was done by using the monthly temperature data from 1901-1984 obtained from 1219 observation stations of the historical climatology network. Although differences in urbanization and seasonality were confirmed in their study, there were limitations in the variability based on the location. Moreover, there was a difference in the degree of data construction between the eastern and western regions.Jones et al. [13] attempted to identify the effect of temperature increase due to urbanization by using the rural-station temperature data for three regions, namely the western Soviet Union, eastern Australia, and eastern China. However, there was a limitation in the study due to the varying numbers of observation stations and analysis periods; furthermore, significant trends...

Analysis of Urban Morphological Effect on the Microclimate of the Urban Residential Area of Kampung Baru in Kuala Lumpur Using a Geospatial Approach

“…This is contrary to the observation in Figure 14d-f in which the UHI peak occurred in the evening as a result of clear sky for the rest of the days. Figure 15 shows the hourly average of UHI intensity over six (6) days. Overall, the hourly average of UHII ranged between 1.0 °C and 4.0 °C, which was equal between the urban and rural areas.…”

“…All calculated values of UHII are positive values, indicating that the high temperature recorded at Kampung Baru contributed to the UHI phenomenon. Figure 15 shows the hourly average of UHI intensity over six (6) days. Overall, the hourly average of UHII ranged between 1.0 • C and 4.0 • C, which was equal between the urban and rural areas.…”

“…Albedo is the amount of solar energy that is reflected by the surface to the surrounding area. Other factors that contribute to UHI effects are building thermal properties, urban form, and anthropogenic heat release [5,6]. Magee [7] described UHI as the average temperature change between the urban and rural areas in Fairbanks, Alaska.…”

Meteorological and Ancillary Data Resources for Climate Research in Urban Areas

“…CHELSA has a global coverage, and it contains monthly mean temperature and precipitation for the time period 1979-2013 at a 30-arc sec-spatial resolution. Recently, [58] employed the CHELSA dataset, validated with independent station data provided by the Global Historical Climatology Network (https://www.ncdc.noaa.gov/dataaccess/land-based-station-data/land-based-datasets/ global-historical-climatology-network-ghcn), to analyze the trend in urban heat island intensity from 1992 to 2012 for eight megacities in Asia. The study revealed the ability of the dataset to capture the characteristics of the urban heat island and a good match between the increase in air temperature and urban sprawl.…”

Monitoring for Changes in Spring Phenology at Both Temporal and Spatial Scales Based on MODIS LST Data in South Korea

“…The change in the local climate as a result of a distinguishing land-use pattern in an urban area is often referred as the urban heat island (UHI) effect. The UHI effect is recognized as being caused by a reduction in the latent heat flux and an increase in sensible heat in urban areas as vegetated and evaporating soil surfaces are replaced by pavement and building materials with relatively impervious and low albedo [37][38][39][40]. Consequently, cities are exposed to climate change from greenhouse gas-induced radiative forcing, and localized effects from urbanization such as the urban heat island.…”