Surface Urban Heat Islands Dynamics in Response to LULC and Vegetation across South Asia (2000–2019)

Urbanization is an increasing phenomenon around the world, causing many adverse effects in urban areas. Urban heat island is are of the most well-known phenomena. In the present study, surface urban heat islands (SUHI) were studied for seven megacities of the South Asian countries from 2000–2019. The urban thermal environment and relationship between land surface temperature (LST), land use landcover (LULC) and vegetation were examined. The connection was explored with remote-sensing indices such as urban thermal field variance (UTFVI), surface urban heat island intensity (SUHII) and normal difference vegetation index (NDVI). LULC maps are classified using a CART machine learning classifier, and an accuracy table was generated. The LULC change matrix shows that the vegetated areas of all the cities decreased with an increase in the urban areas during the 20 years. The average LST in the rural areas is increasing compared to the urban core, and the difference is in the range of 1–2 (°C). The SUHII linear trend is increasing in Delhi, Karachi, Kathmandu, and Thimphu, while decreasing in Colombo, Dhaka, and Kabul from 2000–2019. UTFVI has shown the poor ecological conditions in all urban buffers due to high LST and urban infrastructures. In addition, a strong negative correlation between LST and NDVI can be seen in a range of −0.1 to −0.6.

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Synergistic Interactions between Urban Heat Islands and Heat Waves: The Impact in Cities Is Larger than the Sum of Its Parts

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-13-02.1 ◽

2013 ◽

Vol 52 (9) ◽

pp. 2051-2064 ◽

Cited By ~ 293

Author(s):

Dan Li ◽

Elie Bou-Zeid

Keyword(s):

Urban Heat Island ◽

Rural Areas ◽

Urban Areas ◽

Heat Waves ◽

Mitigation Strategies ◽

Urban Heat Islands ◽

Heat Island ◽

Heat Islands ◽

Urban Heat ◽

The Impact

AbstractCities are well known to be hotter than the rural areas that surround them; this phenomenon is called the urban heat island. Heat waves are excessively hot periods during which the air temperatures of both urban and rural areas increase significantly. However, whether urban and rural temperatures respond in the same way to heat waves remains a critical unanswered question. In this study, a combination of observational and modeling analyses indicates synergies between urban heat islands and heat waves. That is, not only do heat waves increase the ambient temperatures, but they also intensify the difference between urban and rural temperatures. As a result, the added heat stress in cities will be even higher than the sum of the background urban heat island effect and the heat wave effect. Results presented here also attribute this added impact of heat waves on urban areas to the lack of surface moisture in urban areas and the low wind speed associated with heat waves. Given that heat waves are projected to become more frequent and that urban populations are substantially increasing, these findings underline the serious heat-related health risks facing urban residents in the twenty-first century. Adaptation and mitigation strategies will require joint efforts to reinvent the city, allowing for more green spaces and lesser disruption of the natural water cycle.

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Monitoring the Detailed Dynamics of Regional Thermal Environment in a Developing Urban Agglomeration

Sensors ◽

10.3390/s20041197 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1197 ◽

Cited By ~ 1

Author(s):

Yue Liu ◽

Hui Li ◽

Peng Gao ◽

Cheng Zhong

Keyword(s):

Urban Heat Island ◽

Land Surface ◽

Temporal Dynamics ◽

Thermal Environment ◽

Urban Heat Islands ◽

Heat Island ◽

Heat Islands ◽

Inner Cities ◽

Urban Heat ◽

Moderate Resolution Imaging Spectroradiometer

Many studies have revealed the characteristics and spatial-temporal dynamics of the thermal environment in specific cities or urban agglomerations (UA), as well as the associated determining factors. However, few studies focus on the changing relationships (the difference, distance, interaction, etc.) among inner cities’ heat islands in a UA, which represent not only the detailed dynamics of regional thermal environment (RTE), but also the changing competition and cooperation among cities in a developing UA. In this study, we used Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) products to map and analyze the detailed dynamics of the Beijing-Tianjin-Hebei (BTH) UA thermal environment. From 2001 to 2015, the mean surface urban heat island intensity (SUHII) of the BTH increased significantly, and the surface urban heat islands (SUHIs) in the southern BTH have rapidly increased, expanded and connected, eventually forming a large heat islands agglomeration. According to correlation analysis, urban sprawl probably led to the expansion and enhance of SUHIs in the south plain, while the forest has significantly alleviated urban heat island effect in northern mountains. The results expose the detailed evolution process of BTH thermal environment, and the changing relationships among the inner cities. In a developing UA, mitigation solutions (e.g., ecological corridors or controlling energy consumption) are in demand to stop the formation of a great heat region.

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Comparasion of NDBI and NDVI as Indicators of Surface Urban Heat Island Effect in Landsat 8 Imagery: A Case Study of Iasi

Present Environment and Sustainable Development ◽

10.1515/pesd-2017-0032 ◽

2017 ◽

Vol 11 (2) ◽

pp. 141-150 ◽

Cited By ~ 7

Author(s):

Paul Macarof ◽

Florian Statescu

Keyword(s):

Urban Heat Island ◽

Rural Areas ◽

Land Surface ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Landsat 8 ◽

Heat Island ◽

Sensing Technology ◽

Urban Heat ◽

Surface Urban Heat Island

Abstract This study compares the normalized difference built-up index (NDBI) and normalized difference vegetation index (NDVI) as indicators of surface urban heat island effects in Landsat-8 OLI imagery by investigating the relationships between the land surface temperature (LST), NDBI and NDVI. The urban heat island (UHI) represents the phenomenon of higher atmospheric and surface temperatures occurring in urban area or metropolitan area than in the surrounding rural areas due to urbanization. With the development of remote sensing technology, it has become an important approach to urban heat island research. Landsat data were used to estimate the LST, NDBI and NDVI from four seasons for Iasi municipality area. This paper indicates than there is a strong linear relationship between LST and NDBI, whereas the relationship between LST and NDVI varies by season. This paper suggests, NDBI is an accurate indicator of surface UHI effects and can be used as a complementary metric to the traditionally applied NDVI.

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Effect of Land Cover Fractions on Changes in Surface Urban Heat Islands Using Landsat Time-Series Images

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16060971 ◽

2019 ◽

Vol 16 (6) ◽

pp. 971 ◽

Cited By ~ 4

Author(s):

Tao Chen ◽

Anchang Sun ◽

Ruiqing Niu

Keyword(s):

Land Cover ◽

Urban Heat Island ◽

Land Surface ◽

Urban Heat Islands ◽

Urban Heat Island Intensity ◽

Heat Island ◽

Impervious Surfaces ◽

Heat Islands ◽

Urban Heat ◽

Surface Urban Heat Island

Man-made materials now cover a dominant proportion of urban areas, and such conditions not only change the absorption of solar radiation, but also the allocation of the solar radiation and cause the surface urban heat island effect, which is considered a serious problem associated with the deterioration of urban environments. Although numerous studies have been performed on surface urban heat islands, only a few have focused on the effect of land cover changes on surface urban heat islands over a long time period. Using six Landsat image scenes of the Metropolitan Development Area of Wuhan, our experiment (1) applied a mapping method for normalized land surface temperatures with three land cover fractions, which were impervious surfaces, non-chlorophyllous vegetation and soil and vegetation fractions, and (2) performed a fitting analysis of fierce change areas in the surface urban heat island intensity based on a time trajectory. Thematic thermal maps were drawn to analyze the distribution of and variations in the surface urban heat island in the study area. A Multiple Endmember Spectral Mixture Analysis was used to extract the land cover fraction information. Then, six ternary triangle contour graphics were drawn based on the land surface temperature and land cover fraction information. A time trajectory was created to summarize the changing characteristics of the surface urban heat island intensity. A fitting analysis was conducted for areas showing fierce changes in the urban heat intensity. Our results revealed that impervious surfaces had the largest impacts on surface urban heat island intensity, followed by the non-chlorophyllous vegetation and soil fraction. Moreover, the results indicated that the vegetation fraction can alleviate the occurrence of surface urban heat islands. These results reveal the impact of the land cover fractions on surface urban heat islands. Urban expansion generates impervious artificial objects that replace pervious natural objects, which causes an increase in land surface temperature and results in a surface urban heat island.

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Emergence of opposite trends in daytime and night-time urban heat island intensities in England

10.5194/egusphere-egu2020-5671 ◽

2020 ◽

Author(s):

Eunice Lo ◽

Dann Mitchell ◽

Sylvia Bohnenstengel ◽

Mat Collins ◽

Ed Hawkins ◽

...

Keyword(s):

Urban Heat Island ◽

Urban Areas ◽

Urban Land Use ◽

Urban Heat Islands ◽

Urban Heat Island Effect ◽

Heat Island ◽

Night Time ◽

Heat Islands ◽

Island Effect ◽

Urban Heat

<p>Urban environments are known to be warmer than their sub-urban or rural surroundings, particularly at night. In summer, urban heat islands exacerbate the occurrence of extreme heat events, posing health risks to urban residents. In the UK where 90% of the population is projected to live in urban areas by 2050, projecting changes in urban heat islands in a warming climate is essential to adaptation and urban planning.</p><p>With the use of the new UK Climate Projections (UKCP18) in which urban land use is constant, I will show that both summer urban and sub-urban temperatures are projected to increase in the 10 most populous built-up areas in England between 1980 and 2080. However, differential warming rates in urban and sub-urban areas, and during day and at night suggest a trend towards a reduced daytime urban heat island effect but an enhanced night-time urban heat island effect. These changes in urban heat islands have implications on thermal comfort and local atmospheric circulations that impact the dispersion of air pollutants. I will further demonstrate that the opposite trends in daytime and night-time urban heat island effects are projected to emerge from current variability in more than half of the studied cities below a global mean warming of 3&#176;C above pre-industrial levels.</p>

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Climate change over UK cities: the urban influence on extreme temperatures in the UK climate projections

Climate Dynamics ◽

10.1007/s00382-021-05883-w ◽

2021 ◽

Author(s):

William J. Keat ◽

Elizabeth J. Kendon ◽

Sylvia I. Bohnenstengel

Keyword(s):

Urban Heat Island ◽

Rural Areas ◽

Land Surface ◽

Urban Areas ◽

Climate Model ◽

Climate Projections ◽

Heat Island ◽

Night Time ◽

Urban Heat ◽

The Uk

AbstractIncreasing summer temperatures in a warming climate will increase the exposure of the UK population to heat-stress and associated heat-related mortality. Urban inhabitants are particularly at risk, as urban areas are often significantly warmer than rural areas as a result of the urban heat island phenomenon. The latest UK Climate Projections include an ensemble of convection-permitting model (CPM) simulations which provide credible climate information at the city-scale, the first of their kind for national climate scenarios. Using a newly developed urban signal extraction technique, we quantify the urban influence on present-day (1981–2000) and future (2061–2080) temperature extremes in the CPM compared to the coarser resolution regional climate model (RCM) simulations over UK cities. We find that the urban influence in these models is markedly different, with the magnitude of night-time urban heat islands overestimated in the RCM, significantly for the warmest nights (up to $$4~^{\circ }$$ 4 ∘ C), while the CPM agrees much better with observations. This improvement is driven by the improved land-surface representation and more sophisticated urban scheme MORUSES employed by the CPM, which distinguishes street canyons and roofs. In future, there is a strong amplification of the urban influence in the RCM, whilst there is little change in the CPM. We find that future changes in soil moisture play an important role in the magnitude of the urban influence, highlighting the importance of the accurate representation of land-surface and hydrological processes for urban heat island studies. The results indicate that the CPM provides more reliable urban temperature projections, due at least in part to the improved urban scheme.

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Quantification of Urban Heat Island-Induced Contribution to Advance in Spring Phenology: A Case Study in Hangzhou, China

Remote Sensing ◽

10.3390/rs13183684 ◽

2021 ◽

Vol 13 (18) ◽

pp. 3684

Author(s):

Yingying Ji ◽

Jiaxin Jin ◽

Wenfeng Zhan ◽

Fengsheng Guo ◽

Tao Yan

Keyword(s):

Surface Temperature ◽

Urban Heat Island ◽

Land Surface Temperature ◽

Land Surface ◽

Urban Areas ◽

Vegetation Index ◽

Heat Island ◽

Spring Phenology ◽

Urban Heat ◽

The Difference

Plant phenology is one of the key regulators of ecosystem processes, which are sensitive to environmental change. The acceleration of urbanization in recent years has produced substantial impacts on vegetation phenology over urban areas, such as the local warming induced by the urban heat island effect. However, quantitative contributions of the difference of land surface temperature (LST) between urban and rural (ΔLST) and other factors to the difference of spring phenology (i.e., the start of growing season, SOS) between urban and rural (ΔSOS) were rarely reported. Therefore, the objective of this study is to explore impacts of urbanization on SOS and distinguish corresponding contributions. Using Hangzhou, a typical subtropical metropolis, as the study area, vegetation index-based phenology data (MCD12Q2 and MYD13Q1 EVI) and land surface temperature data (MYD11A2 LST) from 2006–2018 were adopted to analyze the urban–rural gradient in phenology characteristics through buffers. Furthermore, we exploratively quantified the contributions of the ΔLST to the ΔSOS based on a temperature contribution separation model. We found that there was a negative coupling between SOS and LST in over 90% of the vegetated areas in Hangzhou. At the sample-point scale, SOS was weakly, but significantly, negatively correlated with LST at the daytime (R2 = 0.2 and p < 0.01 in rural; R2 = 0.14 and p < 0.05 in urban) rather than that at nighttime. Besides, the ΔSOS dominated by the ΔLST contributed more than 70% of the total ΔSOS. We hope this study could help to deepen the understanding of responses of urban ecosystem to intensive human activities.

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Evolutionary Consequences of the Urban Heat Island

Urban Evolutionary Biology ◽

10.1093/oso/9780198836841.003.0007 ◽

2020 ◽

pp. 91-110 ◽

Cited By ~ 3

Author(s):

Sarah E. Diamond ◽

Ryan A. Martin

Keyword(s):

Urban Heat Island ◽

Urban Areas ◽

Climatic Conditions ◽

Urban Heat Islands ◽

Heat Island ◽

Heat Islands ◽

Physiological Tolerance ◽

Downstream Effects ◽

Urban Heat ◽

Evolutionary Consequences

As humans continue to modify the climatic conditions organisms encounter, downstream effects on the phenotypes of organisms are likely to arise. In particular, the worldwide proliferation of human settlements rapidly generates pockets of localized warming across the landscape. These urban heat island effects are frequently intense, especially for moderate to larger sized cities, where urban centres can be several degrees Celsius warmer compared with nearby non-urban areas. Although organisms likely ameliorate the effects of warming through phenotypic plasticity, the evolution of thermally sensitive traits may be an important yet underappreciated means of survival. Recent work suggests the potential for contemporary evolutionary change in association with urban heat islands across a diverse suite of traits from morphology to physiological tolerance, growth rate, and metabolism. This chapter reviews and synthesizes this work. It first develops a comprehensive set of predictions for adaptive evolutionary changes in morphology, physiology, and life-history traits driven by urban heat islands. It then evaluates these predictions with regard to the burgeoning literature on urban evolution of thermally sensitive traits.

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Urban Thermal Environment and Heat Island in Ho Chi Minh City, Vietnam from Remote Sensing Data

10.20944/preprints201701.0129.v1 ◽

2017 ◽

Author(s):

Van Tran Thi ◽

Bao Ha Duong Xuan ◽

Mai Nguyen Thi Tuyet

Keyword(s):

Surface Temperature ◽

Urban Heat Island ◽

Rural Areas ◽

Land Surface ◽

Urban Areas ◽

Ho Chi Minh City ◽

Heat Island ◽

Urban Heat ◽

Surface Urban Heat Island ◽

The Impact

In urban area, one of the great problem is the rise of temperature, which leads to form the urban heat island effect. This paper refers to the trend of the urban surface temperature extracted from the Landsat images from which to consider changes in the formation of surface urban heat island for the north of Ho Chi Minh city in period 1995-2015. Research has identified land surface temperature from thermal infrared band, according to the ability of the surface emission based on characteristics of normalized difference vegetation index NDVI. The results showed that temperature fluctuated over the city with a growing trend and the gradual expansion of the area of the high-temperature zone towards the suburbs. Within 20 years, the trend of the formation of surface urban heat island with two typical locations showed a clear difference between the surface temperature of urban areas and rural areas with space expansion of heat island in 4 times in 2015 compared to 1995. An extreme heat island located in the inner city has an area of approximately 18% compared to the total area of the region. Since then, the solution to reduce the impact of urban heat island has been proposed, in order to protect the urban environment and the lives of residents in Ho Chi Minh City becoming better

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Surface Urban Heat Island Assessment of a Cold Desert City: A Case Study over the Isfahan Metropolitan Area of Iran

Atmosphere ◽

10.3390/atmos12101368 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1368

Author(s):

Alireza Karimi ◽

Pir Mohammad ◽

Sadaf Gachkar ◽

Darya Gachkar ◽

Antonio García-Martínez ◽

...

Keyword(s):

Urban Heat Island ◽

Metropolitan Area ◽

Negative Correlation ◽

Land Surface ◽

Vegetation Index ◽

Urban Heat Islands ◽

Heat Island ◽

Cold Desert ◽

Urban Heat ◽

Surface Urban Heat Island

This study investigates the diurnal, seasonal, monthly and temporal variation of land surface temperature (LST) and surface urban heat island intensity (SUHII) over the Isfahan metropolitan area, Iran, during 2003–2019 using MODIS data. It also examines the driving factors of SUHII like cropland, built-up areas (BI), the urban–rural difference in enhanced vegetation index (ΔEVI), evapotranspiration (ΔET), and white sky albedo (ΔWSA). The results reveal the presence of urban cool islands during the daytime and urban heat islands at night. The maximum SUHII was observed at 22:30 pm, while the minimum was at 10:30 am. The summer months (June to September) show higher SUHII compared to the winter months (February to May). The daytime SUHII demonstrates a robust positive correlation with cropland and ΔWSA, and a negative correlation with ΔET, ΔEVI, and BI. The nighttime SUHII displays a negative correlation with ΔET and ΔEVI.

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