Experimental studies on the effects of green space and evapotranspiration on urban heat island in a subtropical megacity in China

Abstract Continuous urban development leads to urban heat island effects. Research suggests that urban green spaces can help effectively reduce urban heat island effects in the summer. Previous studies have mainly focused on the influence of different underlying surfaces on air cooling and humidification. There is a lack of in-depth research on the relationship between park structure and microclimatic effects. Here, we examined the main landscape parameters of green spaces in 15 parks located in Suzhou Industrial Park (SIP) with a subtropical maritime monsoon climate zone during the summer to analyze their influence on the microclimate. The average cooling and humidifying effect of medium-size green spaces was most significant during high-temperature hours in the daytime. When the distance to a water body was the same, the average cooling and humidifying effect ranked as follows: large-size green space > small-size green space > medium-size green space. We explored the mechanisms of the local cooling and humidifying effects of woodland and water areas in parks by numerical simulations. The significance of the cooling and humidifying effects of water areas of different shapes was as follows: annular water > massive water > banded water. This confirmed that the shape and size of water areas within a green space has a significant influence on local cooling and humidification.

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Spatial Analysis of Surface Urban Heat Islands in Four Rapidly Growing African Cities

Remote Sensing ◽

10.3390/rs11141645 ◽

2019 ◽

Vol 11 (14) ◽

pp. 1645 ◽

Cited By ~ 26

Author(s):

Matamyo Simwanda ◽

Manjula Ranagalage ◽

Ronald C. Estoque ◽

Yuji Murayama

Keyword(s):

Urban Heat Island ◽

Green Space ◽

Urban Landscape ◽

Impervious Surface ◽

Green Spaces ◽

Heat Island ◽

Impervious Surfaces ◽

African Cities ◽

Urban Rural ◽

Urban Heat

Africa’s unprecedented, uncontrolled and unplanned urbanization has put many African cities under constant ecological and environmental threat. One of the critical ecological impacts of urbanization likely to adversely affect Africa’s urban dwellers is the urban heat island (UHI) effect. However, UHI studies in African cities remain uncommon. Therefore, this study attempts to examine the relationship between land surface temperature (LST) and the spatial patterns, composition and configuration of impervious surfaces/green spaces in four African cities, Lagos (Nigeria), Nairobi (Kenya), Addis Ababa (Ethiopia) and Lusaka (Zambia). Landsat OLI/TIRS data and various geospatial approaches, including urban–rural gradient, urban heat island intensity, statistics and urban landscape metrics-based techniques, were used to facilitate the analysis. The results show significantly strong correlation between mean LST and the density of impervious surface (positive) and green space (negative) along the urban–rural gradients of the four African cities. The study also found high urban heat island intensities in the urban zones close (0 to 10 km) to the city center for all cities. Generally, cities with a higher percentage of the impervious surface were warmer by 3–4 °C and vice visa. This highlights the crucial mitigating effect of green spaces. We also found significant correlations between the mean LST and urban landscape metrics (patch density, size, shape, complexity and aggregation) of impervious surfaces (positive) and green spaces (negative). The study revealed that, although most African cities have relatively larger green space to impervious surface ratio with most green spaces located beyond the urban footprint, the UHI effect is still evident. We recommend that urban planners and policy makers should consider mitigating the UHI effect by restoring the urban ecosystems in the remaining open spaces in the urban area and further incorporate strategic combinations of impervious surfaces and green spaces in future urban and landscape planning.

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Conversion of Abandoned Property to Green Space as a Strategy to Mitigate the Urban Heat Island Investigated with Numerical Simulations

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0093.1 ◽

2020 ◽

Vol 59 (11) ◽

pp. 1827-1843

Author(s):

Timothy J. Cady ◽

David A. Rahn ◽

Nathaniel A. Brunsell ◽

Ward Lyles

Keyword(s):

Numerical Simulations ◽

Urban Heat Island ◽

Green Space ◽

Green Spaces ◽

Heat Island ◽

Impervious Surfaces ◽

Vacant Lots ◽

Local Cooling ◽

Aggressive Approach ◽

Urban Heat

AbstractImpervious surfaces and buildings in the urban environment alter the radiative balance and surface energy exchange and can lead to warmer temperatures known as the urban heat island (UHI), which can increase heat-related illness and mortality. Continued urbanization and anthropogenic warming will enhance city temperatures worldwide, raising the need for viable mitigation strategies. Increasing green space throughout a city is a viable option to lessen the impacts of the UHI but can be difficult to implement. The potential impact of converting existing vacant lots in Kansas City, Missouri, to green spaces is explored with numerical simulations for three heat-wave events. Using data on vacant property and identifying places with a high fraction of impervious surfaces, the most suitable areas for converting vacant lots to green spaces is determined. Land-use/land-cover datasets are modified to simulate varying degrees of feasible conversion of urban to green spaces in these areas, and the local cooling effect using each strategy is compared with the unmodified simulation. Under more aggressive greening strategies, a mean local cooling impact of 0.5°–1.0°C is present within the focus area itself during the nighttime hours. Some additional cooling via the “park cool island” is possible downwind of the converted green spaces under the more aggressive scenarios. Although moderate and conservative strategies of conversion could still lead to other benefits, those strategies have little impact on cooling. Only an aggressive approach yields significant cooling.

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The influence of small green space type and structure at the street level on urban heat island mitigation

Urban Forestry & Urban Greening ◽

10.1016/j.ufug.2016.12.005 ◽

2017 ◽

Vol 21 ◽

pp. 203-212 ◽

Cited By ~ 50

Author(s):

Jonghoon Park ◽

Jun-Hyun Kim ◽

Dong Kun Lee ◽

Chae Yeon Park ◽

Seung Gyu Jeong

Keyword(s):

Urban Heat Island ◽

Green Space ◽

Heat Island ◽

Street Level ◽

Urban Heat

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Spatial correlation analysis between impervious surface, green space and urban heat island

2011 19th International Conference on Geoinformatics ◽

10.1109/geoinformatics.2011.5980744 ◽

2011 ◽

Cited By ~ 1

Author(s):

Xiaoping Zhang ◽

Mingxi Zhang ◽

Jun Zhang ◽

Yingbao Yang

Keyword(s):

Correlation Analysis ◽

Urban Heat Island ◽

Spatial Correlation ◽

Green Space ◽

Impervious Surface ◽

Heat Island ◽

Urban Heat ◽

Spatial Correlation Analysis

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Modelling urban cooling island impact of green space and water bodies on surface urban heat island in a continuously developing urban area

Modeling Earth Systems and Environment ◽

10.1007/s40808-018-0456-7 ◽

2018 ◽

Vol 4 (2) ◽

pp. 501-515 ◽

Cited By ~ 7

Author(s):

Sasanka Ghosh ◽

Arijit Das

Keyword(s):

Urban Heat Island ◽

Urban Area ◽

Green Space ◽

Water Bodies ◽

Heat Island ◽

Urban Heat ◽

Surface Urban Heat Island ◽

Urban Cooling Island

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Study of the Relationship between Heat Island Effect and Urbanization Expansion Based on Index Method of Xi'an City

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.685.433 ◽

2014 ◽

Vol 685 ◽

pp. 433-438

Author(s):

Ling Han ◽

Yu Zhang ◽

Xi Tao Huang ◽

Wen Tao Ma

Keyword(s):

Urban Heat Island ◽

Green Space ◽

Urban Expansion ◽

Heat Island ◽

Landsat Images ◽

Index Method ◽

The Past ◽

Urban Heat ◽

The Relationship ◽

Xi’An City

In this paper, it extracted and monitored the ground temperature, urban land, green space, water, bare ground in Xi'an used LANDSAT images in different periods of 1995, 2006 and 2013, analyzed the relationship between the changes of urban underlying surface and heat island in the past 20 years in Xi'an city, which is in order to provide basic information for urban rational designation and improve environmental conditions. The study found: it was feasible and accurate to study of the relationship between urban heat island and urbanization expansion based on index method, which had more statistically significant compared to the traditional classification methods and achieved a shift from qualitative to quantitative. The results show that: the urban heat island and Xi'an urbanization expansion is significantly correlated. The urban heat island is negatively correlated with green space and water body, and is positively correlated with buildings and bare land; in the past 20 years, Xi'an city expanded approximately 4.25 times, the heat island area continued to grow, but the strength enhanced first and then weakened; since 2006, the green space and water area have grown within the third ring road, the urban structure has become more rational, the trend of urban heat island has slowed. Keyword:UHI;Urban expansion;NDBI;NDVI;MNDWI;BI

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Urban Green Space Layouts and Urban Heat Island: Case Study on Apartment Complexes in South Korea

Journal of Urban Planning and Development ◽

10.1061/(asce)up.1943-5444.0000414 ◽

2018 ◽

Vol 144 (2) ◽

pp. 04018004 ◽

Cited By ~ 3

Author(s):

Soo-Young Moon ◽

Jonghoon Kim ◽

Wai K. O. Chong ◽

Samuel T. Ariaratnam

Keyword(s):

South Korea ◽

Urban Heat Island ◽

Green Space ◽

Urban Green Space ◽

Heat Island ◽

Urban Green ◽

Urban Heat ◽

Apartment Complexes

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Investigating Spatiotemporal Patterns of Surface Urban Heat Islands in the Hangzhou Metropolitan Area, China, 2000–2015

Remote Sensing ◽

10.3390/rs11131553 ◽

2019 ◽

Vol 11 (13) ◽

pp. 1553 ◽

Cited By ~ 4

Author(s):

Fei Li ◽

Weiwei Sun ◽

Gang Yang ◽

Qihao Weng

Keyword(s):

Spatial Distribution ◽

Population Density ◽

Urban Heat Island ◽

Metropolitan Area ◽

Green Space ◽

Utilization Efficiency ◽

Heat Island ◽

Rapid Urbanization ◽

Urban Heat ◽

Surface Urban Heat Island

Rapid urbanization has resulted in a serious urban heat island effect in the Hangzhou Metropolitan Area of China during the past decades, negatively impacting the area’s sustainable development. Using Landsat images from 2000 to 2015, this paper analysed the spatial-temporal patterns in a surface urban heat island (SUHI) and investigated its relationship with urbanization. The derived land surface temperature (LST) and surface urban heat island intensity (SUHII) were used to quantify the SUHI effect. Spatial analysis was employed to illustrate the spatial distribution and evolution of a SUHI. The geographically weighted regression (GWR) model was implemented to identify statistically significant factors that influenced the change of SUHII. The results show that hot and very hot spot areas increased from 387 km2 in 2000 to 615 km2 in 2015, and the spatial distribution changed from a monocentric to a polycentric pattern. The results also indicate that high-LST clusters moved towards the east, which was consistent with urban expansion throughout the study period. These changes mirrored the intensive development of three satellite towns. The statistical analysis suggests that both population density (e.g., changes in population density, CPOPD) and green space (e.g., changes in green space fraction, CGSF) strongly affected the changes in SUHII at different stages of the urbanization process. Increasing in population density has a lastingly effect on elevating the SUHII, whereas increasing green space has a constantly significant effect in mitigating the SUHII. These findings suggest that urban planners and policymakers should protect the cultivated lands in suburbs and exurbs, and make efforts to improve the utilization efficiency of construction land by encouraging the migrating population to live within the existing built-up regions.

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