Development Of Urban Heat Island Research Articles

Spatiotemporal Influence of Land Use/Land Cover Change Dynamics on Surface Urban Heat Island: A Case Study of Abuja Metropolis, Nigeria

Rapid urbanization in cities and urban centers has recently contributed to notable land use/land cover (LULC) changes, affecting both the climate and environment. Therefore, this study seeks to analyze changes in LULC and its spatiotemporal influence on the surface urban heat islands (UHI) in Abuja metropolis, Nigeria. To achieve this, we employed Multi-temporal Landsat data to monitor the study area’s LULC pattern and land surface temperature (LST) over the last 29 years. The study then analyzed the relationship between LULC, LST, and other vital spectral indices comprising NDVI and NDBI using correlation analysis. The results revealed a significant urban expansion with the transformation of 358.3 sq. km of natural surface into built-up areas. It further showed a considerable increase in the mean LST of Abuja metropolis from 30.65 °C in 1990 to 32.69 °C in 2019, with a notable increase of 2.53 °C between 2009 and 2019. The results also indicated an inverse relationship between LST and NDVI and a positive connection between LST and NDBI. This implies that urban expansion and vegetation decrease influences the development of surface UHI through increased LST. Therefore, the study’s findings will significantly help urban-planners and decision-makers implement sustainable land-use strategies and management for the city.

Influences of wind speed, sky conditions, land use and land cover characteristics on the magnitude of the urban heat island in Seoul: An exploratory analysis

Prevailing weather conditions and urban morphology are among the fundamental drivers of the radiative and turbulent exchange processes that inherently result in an urban heat island (UHI). The influence of such drivers varies with temporal changes and must be estimated using recent and sufficiently large meteorological and land-use datasets. We used the most recent in-situ temperature observations collected from a spatially extensive network of 54 automatic weather stations (AWS) gathered over a period of nine years to quantify the influence of wind speed, cloud coverage and land use characteristics on the magnitude of UHI in Seoul city. Through an analysis of variance and combined clustering techniques, we found increased UHI intensities (UHII) under low wind speeds, clear skies and densely built areas. Changes of 0.5 m/s in wind speeds and 1 octa in cloud coverage corresponded to 0.20 °C and 0.24 °C reductions in UHII, respectively. Also, statistically significant differences in peak diurnal UHII values of 1.2 °C were estimated between densely built and sparsely built areas. The obtained results shed light on the factors likely to influence UHI development in Seoul city, and fuel scientific discourse on the development of sustainable cities and effective policies for the management of the built environment.

Potential benefit of photovoltaic pavement for mitigation of urban heat island effect

Pavements in roadway and parking lots occupy large urban areas and contribute to the development of urban heat island (UHI). Photovoltaic (PV) pavement can use PV panels on conventional asphalt concrete (AC) pavement to harvest solar energy at light traffic conditions. This study aimed to evaluate the potential benefit of PV pavement to mitigate UHI effect. First, the heat transfer models for AC and PV pavements were developed. The pavement surface temperature and heat output from pavement surface to near-surface environment were then calculated that were used as the indicator of pavement contribution to UHI effect. A parametric study was conducted to analyze the influences of front glass and wind speed on thermal performance of PV pavement. Varying the thickness and transmittance of front glass have shown noticeable influences on pavement temperature, while the change of heat output is limited. Although the increase of average wind speed results in lower pavement temperatures, the heat output experiences slightly increase. The comparison of PV pavement and conventional AC pavement shows that PV pavement can decrease surface temperature by 3–5 °C in summer and generate 11–12% less heat output at various climate conditions.

Identifikasi Pertumbuhan Urban Heat Island secara Spasial-Temporal di Kota Palangka Raya Menggunakan Penginderaan Jauh dan Sistem Informasi Geografis

Developments in the city of Palangka Raya y giving different temperature between urban and sub-urban. Phenomenon that cities have warmer temperatures than sub-urban and rural areas called Urban Heat Island (UHI). This study aims to find out about the development of the UHI phenomenon in the city of Palangka Raya from 2000 to 2018 using remote sensing and geographical system. Based on the analysis of the TIR band landsat 7, in Kota Palangka Raya since 2000 has been UHI phenomenon, where high Land Surface Temperature (LST) was found dominantly in urban areas compared to sub-urban areas . In 2018, as Palangka Raya city had developed, based on the result of TIR band Landsat 8, the distribution of high LST not only found in the urban area, but in the sub-urban zone, especially at Menteng Urban Village and Panarung Urban Village. The development of UHI in Palangka Raya city over eighteen years (2000-2018) show in the sub-urban area experienced changes of UHIindex’s area more dynamic than the urban area. Urban development causing to conversion of vegetated land into impervious land, which greatly affects the energy balance. The increase in impervious areas causes more solar radiation that reaches the surfaces of the earth more absorbing and it is converted into sensible thermal energy which increases the surface temperature.

Examining Spatio-Temporal Characteristics of Urban Heat Islands and Factors Driving Them in Hangzhou, China

The urban environment is a complex system featuring interactions between nature and humans. Scant research on urban areas has analyzed and assessed urban heat islands (UHIs) from the perspectives of nature and humans. This study analyzes the spatio-temporal characteristics of UHIs in Hangzhou in China in the context of the relationship between nature and humans based on the standard deviational ellipse, Pearson correlation analysis, and principal component analysis. The results show the following: (1) From 2000 to 2020, the coverage of UHIs in the main urban area of Hangzhou decreased, but areas with sub-high temperatures and high temperatures increased. (2) From 2000 to 2020, the main axis of the spatial development of UHIs persisted along the northwestsoutheast direction. The spatial pattern of UHIs in Hangzhou was closely related to the direction of urban development. (3) The results of principal component analysis show that socio-economic activities, surface coverage and topography were the major factors influencing UHIs in Hangzhou. (4) Natural factors have slowed the development of UHIs while human factors have aggravated their formation, where the former contributed more significantly to them than the latter. For each unit of change in nine factors that were considered, the surface temperature in the study area decreased by 0.166 units.

A Method for Selecting the Typical Days with Full Urban Heat Island Development in Hot and Humid Area, Case Study in Guangzhou, China

The urban heat island (UHI) poses a significant threat to urban ecosystems, human health, and urban energy systems. Hence, days with a relatively higher UHI intensity should be selected for UHI observation and analysis. However, there is still a lack in the method and criteria for selecting the typical meteorological days for UHI survey and simulation. In this study, field measurements were conducted based on Local Climate Zone (LCZ) schemes over a one-year period to assess the UHI behavior in Guangzhou, China. The relationship between the diurnal temperature range (DTR) and UHI intensity was evaluated and analyzed quantitatively under different meteorological conditions classified by precipitation. The average daily maximum UHI intensity (UHIImax) during precipitation days was approximately 1.8 °C lower than that during non-precipitation days, confirming that precipitation has a negative effect on UHI development. The monthly DTR distribution was similar to the daily UHIImax distribution, which was higher in autumn and winter, but lower in spring and summer. DTR has a significant linear correlation with the daily UHIImax, with a Pearson’s correlation coefficient of >0.7 and statistical significance of <0.001. Based on a quantitative evaluation of our results, we determined that 10 °C could be regarded as the appropriate DTR threshold to identify the meteorological conditions conducive to UHI development; the meteorological conditions exhibited a high daily UHIImax in Guangzhou. This study provides a simple method to select typical meteorological days for UHI measurement and simulation, and a method to early-warning of intense UHI events based on weather forecasts.

The Multiple-Scale Nature of Urban Heat Island and Its Footprint on Air Quality in Real Urban Environment

The complex interaction between the Urban Heat Island (UHI), local circulation, and air quality requires new methods of analysis. To this end, this study investigates the multiple scale nature of the UHI and its relationship with flow and pollutant dispersion in urban street canyons with and without the presence of vegetation. Two field experimental campaigns, one in summer and one in winter, were carefully designed in two parallel urban street canyons in the city of Bologna (44°29′ N, 11°20′ E; Italy) characterized by a similar orientation with respect to the impinging background flow but with a different aspect ratio and a different presence of vegetation. In addition to standard meteorological variables, the dataset collected included high-resolution flow data at three levels and concentration data of several pollutants. The UHI has been evaluated by combining surface temperature of building facades and ground surfaces acquired during two intensive thermographic campaigns with air temperature from several stations in order to verify the presence of intra-city neighborhood scale UHIs additional to the more classical urban–rural temperature differences. The presence of trees together with the different morphologies was shown to mitigate the UHI intensity of around 40% by comparing its value in the center of the city free of vegetation and the residential area. To capture the multiple-scale nature of UHI development, a simple relationship for the UHI convergence velocity, used as a surrogate for UHI strength, is proposed and used to establish the relationship with pollutant concentrations. The reliability of the proposed relationship has been verified using a Computational Fluid Dynamics (CFD) approach. The existence of a robust relationship between UHI strength and pollutant concentration may indicate that the positive effect of mitigation solutions in improving urban thermal comfort likely will also positively impact on air pollution. These results may be useful for a quick assessment of the pollutant accumulation potential in urban street canyons.

Impact of spatiotemporal land-use and land-cover changes on surface urban heat islands in a semiarid region using Landsat data

ABSTRACT Many factors are involved in urban heat island development, such as lack of green spaces, improper choice of building materials, densification, and other human activities. The aim of this research was to quantify the effects of land-use/land-cover (LU/LC) changes on urban land surface temperature (LST) during a 25-year period (1993–2018) for the semiarid Shiraz City in southern Iran using Landsat data (TM, ETM+, and OLI/TIRS) and machine learning algorithms. Five main LU/LC classes, such as orchard, vegetation, bare surface, asphalt cover, and built-up areas, were identified using a support vector machine algorithm. Landsat images were used to retrieve normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI). The results showed that the mean LST over the entire study domain increased considerably between 1993 and 2018, due to urbanization, decrease of green areas, and increasing industrial areas. Built-up areas increased considerably by 25.8% from 80 to 100.6 km2 between 1993 and 2018, while vegetation cover decreased dramatically by 69.3%. Mean LST increased from 38.4 to 40.2°C during the 25-year period with a significant increase of 3.9°C between 2013 and 2018. In addition, the Urban heat island Ratio Index (URI) displayed a substantial upward trend during the 25-year period.

Influence of synoptic scale atmospheric circulation on the development of urban heat island in Prague and Bucharest

This study has analysed the development of the urban heat island (UHI) under various synoptic scale atmospheric circulation for two large cities – Prague in central Europe and Bucharest in south-eastern Europe, including seasonal differences and long-term changes. At the best of our knowledge, it is the first comparison between two European cities from this perspective. Analysis was conducted on the base of minimum air temperature data from pairs of urban and peri-urban stations. The average UHI intensity is 2.3 °C for Prague and 1.8 °C for Bucharest, it exceeds 4 °C in 6–10% of cases, and the highest values occur in August in both cities. The annual course of monthly mean values of UHI intensities has higher amplitude in Bucharest (1.2 °C) than Prague (0.6 °C). Synoptic scale circulation is classified according to mean sea level pressure data from ECMWF Era-Interim reanalysis using cost733class software. The results show that UHI is more intense under anticyclonic situations with southern winds in the both cities. Over 1981–2016, we found that the UHI intensity followed statistically significant increasing trend, much larger trend for Bucharest than Prague (3.3 °C vs. 1.3 °C / 100 years).

RS and GIS Supported Urban LULC and UHI Change Simulation and Assessment

Rapid urbanization has become a major urban sustainability concern due to environmental impacts, such as the development of urban heat island (UHI) and the reduction of urban security states. To date, most research on urban sustainability development has focused on dynamic change monitoring or UHI state characterization, while there is little literature on UHI change analysis. In addition, there has been little research on the impact of land use and land cover changes (LULCCs) on UHI, especially simulates future trends of LULCCs, UHI change, and dynamic relationship of LULCCs and UHI. The purpose of this research is to design a remote sensing-based framework that investigates and analyzes how the LULCCs in the process of urbanization affected thermal environment. In order to assess and predict the impact of LULCCs on urban heat environment, multitemporal remotely sensed data from 1986 to 2016 were selected as source data, and Geographic Information System (GIS) methods such as the CA-Markov model were employed to construct the proposed framework. The results showed that (1) there has been a substantial strength of urban expansion during the 40-year study period, (2) the farthest distance urban center of gravity moves from north-northeast (NEE) to west-southwest (WSW) direction, (3) the dominate temperature was middle level, sub-high level, and high level in the research area, (4) there was a higher changing frequency and range from east to west, and (5) there was a significant negative correlation between land surface temperature and vegetation and significant positive correlation between temperature and human settlement.

Quantitative methods for identifying meteorological conditions conducive to the development of urban heat islands

Meteorological conditions significantly influence the development of urban heat islands (UHIs); hence, a reliable assessment and understanding of UHIs depends primarily on the days selected for observation and analysis. Numerous studies were conducted on the characteristics and causes of UHIs; however, few studies focused on the methods and criteria for identifying meteorological conditions conducive to UHI development. The objective of this study is to investigate the performances of four quantitative methods for identifying meteorological conditions conducive to UHI development based on three years of observations in Nanjing, China. The methods include the widely used method based on cloud cover and wind speed and three methods that combine the effects of multiple meteorological variables on UHIs into a single indicator. Correlations analysis between the daily maximum urban heat island intensity (UHIImax) and the meteorological variables indicates that it is inadequate to identify meteorological conditions conducive to UHI development using a single variable, such as solar radiation, cloud cover, or wind speed. The correlations between the daily UHIImax and the indicators are significant (r > 0.60, P < 0.001). The observations are split into calibration and validation sets. Then, the performances of the four methods are evaluated, and the appropriate thresholds for identifying meteorological conditions conducive to UHI development in Nanjing are determined. The results demonstrate that all four methods can be used for identifying meteorological conditions conducive to UHI development in Nanjing. The features and limitations of the four methods and the potential applications are discussed.

Transforming Urban Systems

Transforming Urban Systems

Exploring temperature indices by deriving relationship between land surface temperature and urban landscape

Global warming and climate change are two indispensable phenomena that cannot be overlooked. These can be inferred to the unrelenting rise in surface temperature globally. Unplanned and speedy urbanization is one of the foremost causes of surface temperature rise as it alters the landscape. Urbanization defines the socio-economic value of city and management but if inadvertent, it can lead to serious insinuations on environmental parameters. As a result of globalization and industrialization, a sheer increase in population was observed due to migration, improved health facilities, better job opportunities and superior living standards. It is necessary to inculcate the demand of these rising urban dwellers in the form of infrastructure, energy, clean air and water. As a result of this, landscape restructuring befalls that can be understood by conversion of green or open spaces into concrete structures. This alters the surface properties causing changes in latent and sensible heat flux leading to increased surface temperature as well as ambient air temperatures. With clustered urban spaces and decrease in vegetation cover and water that acts as sinks, the temperature of urban region shoots more than nearby rural areas leading to the development of urban heat islands. These parameters are directly and indirectly related to air pollution, increased summer days, energy requirement, heat-related diseases, emission of GHGs (greenhouse gases). The communication focuses on the recent challenges and criticism faced by developing Indian cities with very minimum landscape to house burgeoning population, immediate strategies and action-plan required to tackle increasing temperatures and mitigate negative environmental impacts and effects on human beings. The study is an attempt to establish a relationship between surface temperature and land use pattern for Kolkata Metropolitan Area. Study also deals with the estimation of various temperature indices for defining and understanding the variation in surface temperature precisely. Application of these results will help in developing necessary policy measures and sustainable actions that are required to reduce anthropogenic effects on urban and natural environment.

Assessing the Impact of Builtup Areas on Development of Urban Heat Island in Lahore, Pakistan

The aim of present study is to evaluate and assess the impact of built-up areas on development of the urbanheat island (UHI).The study mainly focused on Lahore, which is one of the mega cities of Pakistan. In terms ofpopulation size, Lahore is the second largest city of Pakistan with 11.13 million inhabitants. The geospatial techniques(Remote Sensing and Geographical Information System) along with statistical applications were applied to find out theLand Cover Land Uses changes and consequent development of builtup areas over the period of 2000 and 2015. Tostudy the UHI, the meteorological data of each 30 minutes for 36 days starting from 30th June 2015 to 4th August 2015were collected through direct on site observation by using digital weather station. The results of UHI were crosschecked by obtaining land surface temperature by using thermal infrared (TIR) band 6 of the Landsat-7 TM. The resultsshow that the LCLU and built environment have direct impact on development of UHI. The areas where there wasmore vegetation cover had less temperature while in urban areas, the temperature was measured higher. Over the periodof 36 days, the average UHI remained 5.5°C and the highest intensity of UHI was observed as 8.3°C thus augmentedresearch rationale. The study suggests establishment of a thick network of automatic weather stations in Lahore togauge the urban heat island intensity and to plant indigenous trees on vacant swaths and develop urban forest tomitigate city’s rising temperature.

Assessing the Impact of Builtup Areas on Development of Urban Heat Island in Lahore, Pakistan

The aim of present study is to evaluate and assess the impact of built-up areas on development of the urbanheat island (UHI).The study mainly focused on Lahore, which is one of the mega cities of Pakistan. In terms ofpopulation size, Lahore is the second largest city of Pakistan with 11.13 million inhabitants. The geospatial techniques(Remote Sensing and Geographical Information System) along with statistical applications were applied to find out theLand Cover Land Uses changes and consequent development of builtup areas over the period of 2000 and 2015. Tostudy the UHI, the meteorological data of each 30 minutes for 36 days starting from 30th June 2015 to 4th August 2015were collected through direct on site observation by using digital weather station. The results of UHI were crosschecked by obtaining land surface temperature by using thermal infrared (TIR) band 6 of the Landsat-7 TM. The resultsshow that the LCLU and built environment have direct impact on development of UHI. The areas where there wasmore vegetation cover had less temperature while in urban areas, the temperature was measured higher. Over the periodof 36 days, the average UHI remained 5.5°C and the highest intensity of UHI was observed as 8.3°C thus augmentedresearch rationale. The study suggests establishment of a thick network of automatic weather stations in Lahore togauge the urban heat island intensity and to plant indigenous trees on vacant swaths and develop urban forest tomitigate city’s rising temperature.

NOCTURNAL AND DIURNAL TRENDS OF SURFACE URBAN HEAT ISLAND INTENSITY: A SEASONAL VARIABILITY ANALYSIS FOR SMART URBAN PLANNING

Abstract. Land management in the limited environment of city regions with immense population pressure is a challenging task. To achieve the goal of sustainable smart cities, reliable spatial information needs to be incorporated in land governance policies. In this study, Landsat 8 satellite bands were processed to derive the land use characteristics which are causing the development of urban heat islands at certain locations. To assess the prolonged effects of heat-trapping in cities, night time temperature data was obtained through in-situ data collection with error within 1 °C. Much higher intensity of urban heat island was observed during the night. The maximum increase of 1.67 °C was noted from day to night temperature for the same heat island. Seasonal analysis between winter and summer months was also carried out. The results suggested that for both day and night summer months produced more critical heat islands with maximum intensity up to 3.48 °C; while in winter the heat island intensity did not exceed 2.18 °C. Through comparative analysis between two cities with varying extent, urbanization and population pressure, it was observed that the maximum intensity of day time temperature was greater in a bigger city and heat islands were less fragmented. Heat islands covered an area of 10.39 km2 over Prayagraj and 28.29 km2 area of Kolkata. The temperature patterns obtained during day and night were statistically validated with the index of impervious surface area, at the significance level of α0.05.

The Urban Heat Island at a Regional University in Kentucky, USA

Constructing buildings, sidewalks, parking lots, and roads inadvertently affects local climate. The best studied example of this, the urban heat island (UHI), manifests as elevated temperatures in developed areas compared to less developed areas nearby. This phenomenon affects many things including plants, wildlife, energy consumption, and human health. We assess the UHI at Eastern Kentucky University (EKU) using simultaneous air temperature observations from two stations. The “urban” station is located on EKU's Richmond campus; the “rural” station is in a non-irrigated pasture 12.9 km away. EKU's heat island follows a typical diurnal pattern, developing during the hours surrounding sunset and dissipating soon after sunrise. Dry air masses with little to no cloud cover and calm winds are favorable for UHI development. Analyzing only nocturnal observations when wind speed was less than 1 m/s, revealed an average urban-rural temperature difference of 3.35°C, though concurrent differences sometimes exceed 10°C. At EKU, the smallest average monthly UHI occurs in February and the largest average monthly UHI occurs in August and September. Strategic tree planting offers an attractive means of mitigating negative impacts on warm season cooling costs and human comfort, while also contributing to campus sustainability goals.

Vertical Structure and Seasonal Features of the Heat Island and Humidity Distribution over Moscow Derived from Satellite Data

The vertical structure and annual variations in the urban heat island (UHI) and dry/wet islands over Moscow are investigated using MetOp satellite data for 2015–2017. It is shown that Moscow is characterized by the dominance of the evening maximum of UHI intensity; however, the UHI intensification during the cold season mainly occurs in the daytime. According to satellite data, the maximum development of UHI over Moscow is observed in the forenoon in January. The urban effect propagates to the height of ~2000 m during the warm season and to the height of 1250 m in the forenoon and to 800 m in the evening during the cold season. During the warm season, UHI is accompanied by the dry island in the forenoon and by the wet island at the upper levels in the evening. The existence of the wet island in the lower air layers was not corroborated. Due to the current accuracy of temperature and humidity retrieval (0.5–1 K and 10%, respectively) as well as due to the low vertical resolution of satellite data, the present research is mainly methodological, and the results are preliminary and open to discussion.

Thermal and optical characterization of asphalt field cores for microscale urban heat island analysis

Pavements contribute significantly to the development of Urban Heat Islands (UHIs). The impact of pavements on UHI depends on multiple material factors, including its thermal and optical properties. Field cores from asphalt concrete (AC) pavements from four locations in Illinois and one in Indiana, USA, were used to evaluate the optical and thermal properties of the corresponding pavements. Thermal conductivity ranged from 1.0 to 3.0 W/mK (average of 2.2 W/mK), diffusivity 0.6–2.0 mm2/s (average of 1.5 mm2/s), and heat capacity 0.7–3.0 MJ/m3K (average of 1.5 MJ/m3K), which differ significantly from values typically recommended in pavement design. The same cores were used to calibrate a simplified bilinear aging albedo model, with the asymptotic albedo and at-construction albedo being largely within the expected range of 0.10–0.20 and 0.05–0.10, respectively. The emissivity was found to be between 0.70 and 0.90, which agrees with values reported in the literature. These properties were used to evaluate the local pavement Radiative Forcing (RFp) and Global Warming Potential (GWP) as well as the diurnal net surface heat flux and surface temperature of the pavements. The RFp varied depending on aging albedo and emissivity, while surface temperature and net surface heat flux also depended on thermal properties.

Moist curing increases the solar reflectance of concrete

Abstract Most people are dwelling in cities, which contain a high density of buildings constructed of concrete or similar materials. Conventional grey-colored concrete is absorptive to solar radiation and discharges the absorbed heat to the air as sensible heat, contributing to the development of urban heat island. While existing studies have attempted to find high-reflective concrete by varying the components of the concrete mix, the influence of cured conditions on the albedo of concrete samples is still unknown and has not been reported. Here we first prepared 120 cement pastes with different water-to-cement ratios and different cementitious materials, and then cured the pastes in an indoor environment and a moist chamber, respectively. After cured in a moist chamber for 28 days and then cured in the air for 365 days, the spectral reflectance of all the pastes was tested. Experimental results indicated that the pastes cured in a moist chamber have an albedo that is 0.01–0.10 greater than those of the pastes cured in an indoor environment, with a greater albedo difference at relatively higher water-to-cement ratios. The results also revealed that when concrete productions, such as concrete roof tiles and concrete paver blocks, are prepared, it is practical to cure such productions in a moist environment to get a high albedo.