Assessment Of Urban Heat Island Research Articles

Evolution and assessment of urban heat island between the years 1998 and 2016: case study of the cities Bratislava and Trnava in western Slovakia

The paper concerns research on urban heat islands (UHIs) and presents case studies of two Slovak cities of different sizes: the capital, Bratislava, and the regional centre, Trnava. The model MUKLIMO_3 was applied to the UHI modelling and a heat wave that occurred between 15 and 23 August 2018 was chosen. Land cover/land use (LC/LU) classes based on the local climate zone (LCZ) concept were used as input for the modelling. The model was validated by data taken from five stations in Bratislava and two in Trnava, and a good rate of agreement between the modelled and measured data was statistically proven. Manifestations of UHI were studied during the whole of the mentioned period by summing the hours when threshold temperature values exceeded 25 and 30 °C. The results for Bratislava show greater variability related to the size of the city and terrain dissection compared with Trnava, which is smaller and situated in a flat terrain. A single representative day, that is, 20 August 2018, was chosen, for which UHI was modelled with three inputs of LC/LU classes: situation in 1998, 2007, and 2016 in order to assess the effect of change of LC/LU classes on the distribution of temperatures. Spatial manifestation of UHI was assessed in the frame of LC/LU classes for 2016 at 12:00, 18:00, and 24:00 in Central European Summer Time. The greatest heat load was modelled in densely built-up LC/LU classes, while forest areas were coolest. In Bratislava, due to a combination of a dissected terrain and UHI, great variability was modelled, with maximum temperature differences of up to 12 °C and, in the territory with homogeneous elevation, up to 6 °C. The UHI field in Trnava is less variable, with modelled temperature differences of up to 3 °C. A comparison of individual time horizons proved the effect of the urbanization process on the change of air temperature by several tenths of a degree Celsius on average.

Assessment of Urban Heat Island in Bilaspur City, Chhattisgarh

Assessment of Urban Heat Island in Bilaspur City, Chhattisgarh

Geoinformatic assessment of urban heat island and land use/cover processes: a case study from Akure

Akure is one of the cities undergoing rapid growth in Nigeria, which has resulted to remarkable Urban Heat Island (UHI) effect. To examine the impact of this development in the city and its environs, this study derived the brightness temperatures and land use land cover (LULC) types using Landsat images between 1984 and 2016, of 190/55 path and row. Normalized Difference Built up Index (NDBI) and Normalized Difference Vegetation Index (NDVI), were used as LULC indicators for sub-pixel analysis. The results of this study revealed a remarkable change in built-up area at the expense of vegetation (forest) and bare lands. The sub-pixels analysis between land use/cover indicators and temperature revealed a strong correlation between LULC and temperature in the area. Findings revealed a 4.63 °C temperature increase in vegetated areas between 1984 and 2016; and an overall temperature values ranged from about 14 to 36 °C, which have been categorized into six classes (< 20 °C, 20 °C to < 24 °C, 24 °C to < 28 °C, 28 °C to < 32 °C, and ≥ 32 °C). The temperature increase over the years and the strong correlation between temperature and land use land cover suggests, that any small undesirable change in land use land cover in the future would lead to severe environmental condition.

Environmental and spatial assessment of urban heat islands in Qalyubia Governorate, Egypt

Environmental and spatial assessment of urban heat islands in Qalyubia Governorate, Egypt

Prediction of land surface temperatures for surface urban heat island assessment over Chandigarh city using support vector regression model

Rapid urbanization is one of the primary reasons for changing the local climate, and there is a high impact on the surrounding areas. Chandigarh is one of the fastest developing cities in India showing rapidly urbanizing agglomeration. Due to the rapid urbanization, natural land surfaces are being replaced by the anthropogenic materials which negatively impacts the ecosystem resulting in urban heat island (UHI) effect. Land surface temperature (LST) is the primary and vital step for the analysis of UHI effect. The present study has been conducted to predict the LSTs for the assessment of UHI effect of the area surrounding Chandigarh city. Remote sensing data from Moderate-Resolution Imaging Spectroradiometer (MODIS) sensor and Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) have been used for the prediction of LST. In the study, support vector regression (SVR) model has been developed from LST values of previous three years along with enhanced vegetation index (EVI), road density (RD) and elevation as input parameters to predict LST. The results of the SVR model have been validated using the data of the year 2014. A comparison of the model estimated LST and measured LST indicates that the range of mean absolute error (MAE) and mean absolute percentage error (MAPE) varies between 0.521 K and 0.525 K and 0.181–0.187%, respectively. Hence, SVR model can be used as a significant tool to predict LST for the assessment of heat island effect at any location. From the sensitivity analysis, it is observed that LST was ultimately the most sensitive to the RD compared to EVI and elevation. The SVR model has been compared with artificial neural networks (ANN) model to estimate the skill score factor of the SVR model (Forecasted) with reference to the ANN (Referred) model. Skill scores calculated for the periods show positive values which clearly depicts the efficacy of SVR model compared to ANN model for better LST prediction.

Application of Low-Cost Sensors for Urban Heat Island Assessment: A Case Study in Taiwan

In the urban environment, the urban heat island effect, the phenomenon of high temperature in the city relative to the suburbs, has become significant due to a large amount of artificial heat dissipation, rare green spaces, high building density, and a large surface material heat capacity. The study of the urban heat island effect has been carried out for many years. Even though many studies have evolved from the measurement and analysis stage to the improvement of the urban heat island effect, the measurement method is still the most important issue of the studies in this field. Basically, the measurement method of the urban heat island effect intensity has three types: remote sensing, mobile transect observation, and fixed station. In order to achieve the dual purpose of reducing research funding requirements and maintaining the accuracy of research results, this study proposes a way to combine mobile transect observation and fixed station. This study exploits the advantages of mobile transect observation and fixed station, and uses low-cost sensors to achieve the basic purpose of urban heat island effect research. First, in this study, low-cost sensors were mounted on mobile vehicles for more than ten mobile transect observations to identify relatively high temperature and low temperature regions in the city; meanwhile, the low-cost sensors were also placed in a simple fixed station to obtain long-term instantaneous urban temperature data. Furthermore, it is possible to analyze the 24-hour full-time variation of the urban heat island effect. Therefore, the results of this study can not only provide a reference for relevant researchers, but can also serve as an important criterion for government departments to establish an “urban heat island effect monitoring system” to achieve the goal of efficient use of the public budget.

Assessment of the urban heat island in the city of Tehran using reliability methods

Climate change affects temperature, magnitude, and also the duration of the Urban Heat Island (UHI), which has severe impacts on the environment, communities, and the people's lives. This study evaluates UHI formation in the city of Tehran (Iran) using a reliability framework, which is able to include related uncertainties into the modeling procedure. First, 2 km air temperature field from Weather and Research Forecasting (WRF) model is downscaled to a 50 m grid spacing using a probabilistic downscaling method, which combines inverse distance weighting (IDW) interpolation and a Bayesian regression model. This downscaling method not only can produce a long record of the fine resolution of the temperature but also improves the WRF temperature outputs' accuracy. The downscaled temperature field is then applied for UHI assessment using the first order reliability methods (MVFOSM and FORM). The results indicate that although the maximum intensity of UHI occurs in the warm months, there is a higher probability for UHI formation in the cold months. Furthermore, it is more probable that UHI forms during the night. UHI formation probabilities indicate that two districts in the central part of the city, mainly composed of old dense buildings, are more exposed to UHI in the warm and the cold months. District 1 that has the lowest probability of UHI formation is located in the most elevated part of the city (close to the Alborz mountain range). Results are invaluable for policy making process and risk management plans to assess severity levels of UHI in different regions based on the probability of event's occurrence.

The Impact of Land Use/Land Cover (LULC) Changes on Land Surface Temperature in Sivas City Center and Its Surroundings and Assessment of Urban Heat Island

Determination of LULC (land use/land cover) changes in urban planning studies is very important. However, LST (land surface temperature) and UHI (urban heat island) directly associated with LU changes are the parameters that should be considered in similar studies. Therefore, Remote Sensing (RS) and Geographic Information Systems (GIS) are commonly used for obtaining this kind of information. In this study, the relationship between LULC, NDVI (Normalized Difference Vegetation Index) and LST in Sivas city center and its surroundings was studied by using Landsat satellite images from 1989 to 2015 and UHI intensity was also demonstrated. The results clearly show that the urban built-up areas and agricultural lands increased while barren land decreased over the study period. The changes in LST can be monitored depending on the construction materials such as the presence of green areas, the city’s unique geographical location and topography. Urban built-up and bare lands have the highest LST and the urban built-up surface temperature showed a fluctuating trend while the rural area temperature showed a tendency to decrease. The urban built-up areas increased, a positive UHI intensity was observed and also an urban heat island formation was determined.

A Satellite Assessment of the Urban Heat Island in Morocco

Urban ecosystems interact with surroundings via land cover changes and their subsequent impact on surface temperature. In emerging countries, large urban agglomerations often form around cities, and only a few studies have evaluated their impact. This study carries out the first ever large-scale assessment of urban heat island (UHI) and reflects on its mitigation in Morocco. The analysis reveals a well-defined UHI in urban areas built within vegetated lands and an urban heat sink (UHS) in urban areas built within arid regions. Both UHI and UHS amplitudes are higher during day than nighttime, emphasizing vegetation physiological activity. This study shows a monotonic increase in UHI amplitude with urban area size. However, unlike previous studies, this analysis shows that, as urban areas built in desert-like environments grow in size, the UHS gradually decreases to ultimately turn into an UHI. On average, cities built within vegetation are warmer than the rural fringe by 1.51 °C during daytime. This suggests that daytime urban heating may exacerbate the potential climate warming. These results also suggest that adapted trees constitute a natural cooling mechanism and should be part of urban heating mitigation in Morocco.

The urban heat island effect in Dutch city centres

In the Netherlands awareness regarding the Urban Heat Island (UHI) was raised relatively recently. Because of this recent understanding, there is a lack of consistent urban micro-meteorological measurements to allow a conventional UHI assessment of Dutch cities during heat waves. This paper argues that it is possible to retrieve relevant UHI information – including adaptation guidelines – from satellite imagery. The paper comprises three parts. The first part consists of a study of suited indicators to identify urban heat islands from which a method is presented based on ground heat flux mapping. The second part proposes heat mitigation strategies and identifies the areas where these strategies could be applied within the hotspots identified in the cities of The Hague, Delft, Leiden, Gouda, Utrecht and Den Bosch. The third part estimates the reduction of urban heat generated by the increase of roof albedo in the hotspots of the six cities. The six cities hotspots are located within the boundaries of the 17th century city centres. In order to avoid interference with cultural values of these historical environments most likely UHI mitigation measures regard improving the thermal behaviour of the city roofs. For instance, applying white coatings on bitumen flat roofs (or replacing them by white single-ply membranes) and replacing sloped roof clay tiles by coloured tiles with cool pigments can reduce the urban heat hotspots by approximately 1.5°C. Remote sensing provides high level information that provide urban planners and policy makers with overall design guidelines for the reduction of urban heat.

Monitoring and assessment of urban heat islands over the Southern region of Cairo Governorate, Egypt

Differencing in both land uses and covers are basically occurred by urbanization and changes of land covers. It has a notable power on the climate, by incorporating with buildings, roads, and other impenetrable surfaces, urban areas have the higher absorption of solar radiation, and it stored larger thermal capacity and conductivity, so the heat through the day and freed night. Consequently, urban areas be likely to be wormer matched with the around rural areas. This temperature difference, in addition to the heat released by transport and industry, adds to the evolving urban heat island (UHI). Study area covers Cairo and Giza Cities, which have a rapid urban expansion over the past three decades due to a high population density, accelerated economic and industrial development.The primary objectives of this work are to map urban heat islands (UHI) intensity for study area using Landsat TM/ETM+/OLI thermal band for the periods 1984-2000-2015. Moreover, to find the relation between land covers with its change rates, land surface temperature (LST), and urban heat islands (UHI).The results exposed that the neural network method is the superior method to produce land cover maps of the study area. Results obtained illustrate the great urban expansion from 1984 to 2015; in addition to spatial and temporal variability in LST in those urban areas, (especially industrial buildings that released a higher temperature than its surroundings), besides, the sizes of UHI in 2015 are greater than 1984.

Assessment of urban heat islands and impact of climate change on socioeconomic over Suez Governorate using remote sensing and GIS techniques

Climate change and its effect on human life and comfort have taken increase attraction. In this paper effect of UHI is analyzed using quantitative thermal, temporal remote sensing and GIS techniques. Series of Landsat TM/ETM, 8 and ASTER images of Suez Governorate acquired in winter season were used to investigate the variation in land surface temperature (LST) from 1988 to 2014 as well as land-use/cover change. NDVI NDBI and LST have been used for classification of the study area. Vulnerable areas for UHI have been assessed over Suez district. The effect of UHI was quantitatively described using urban thermal field variance index (UTFVI). Results indicate that there are increases in the overall temperature between years 1988 and 2014. Suez and Al-Arbin districts which are the most populated, highly density built-up and rarely vegetation zones in Suez governorate experiences a huge problem of UHI. UHI phenomenon represents total weight of 40.84% and 46.3% of their areas respectively. It is found that the mean temperature of UHI areas of Al-Arbin and Al-Suez districts was 7.5 above mean of District temperature. While the value of UHI of suburban zone e.g. Ataqa and AL-Ganayin was 2.5 degree above district mean. The results indicate that changes in UTFVI distribution can be predominantly related to the expansion of urban area during the study time period. The hot spot of UTFVI were found mainly in the built-up areas especially densely populated district and in heavily industrial district. It is the vulnerable areas to UHI.

Assessment of Urban Heat Island through Remote Sensing in Nagpur Urban Area Using Landsat 7 ETM+ Satellite Images

Assessment of Urban Heat Island through Remote Sensing in Nagpur Urban Area Using Landsat 7 ETM+ Satellite Images

Assessment of Urban Heat Islands in Small- and Mid-Sized Cities in Brazil

Urban heat islands (UHIs) in large cities and different climatic regions have been thoroughly studied; however, their effects are becoming a common concern in smaller cities as well. We assessed UHIs in three tropical cities, analyzing how synoptic conditions, urban morphology, and land cover affect the heat island magnitude. Data gathering involved mobile surveys across Paranavaí (Paraná), Rancharia (São Paulo), and Presidente Prudente (São Paulo), Brazil, during summer evenings (December 2013–January 2014). Temperature data collected over five days in each city point to heat islands with magnitudes up to 6 °C, under calm synoptic conditions, whereas summer average UHI magnitudes peak at 3.7 °C. In addition, UHI magnitudes were higher in areas with closely spaced buildings and few or no trees and building materials that are not appropriate for the region’s climate and thermal comfort.

Comparative Vulnerability Assessment of Urban Heat Islands in Two Tropical Cities in Indonesia

Comparative Vulnerability Assessment of Urban Heat Islands in Two Tropical Cities in Indonesia

The urban heat island effect in Dutch city centres

In the Netherlands awareness regarding the Urban Heat Island (UHI) was raised relatively recently. Because of this recent understanding, there is a lack of consistent urban micro-meteorological measurements to allow a conventional UHI assessment of Dutch cities during heat waves. This paper argues that it is possible to retrieve relevant UHI information – including adaptation guidelines – from satellite imagery. The paper comprises three parts. The first part consists of a study of suited indicators to identify urban heat islands from which a method is presented based on ground heat flux mapping. The second part proposes heat mitigation strategies and identifies the areas where these strategies could be applied within the hotspots identified in the cities of The Hague, Delft, Leiden, Gouda, Utrecht and Den Bosch. The third part estimates the reduction of urban heat generated by the increase of roof albedo in the hotspots of the six cities. The six cities hotspots are located within the boundaries of the 17th century city centres. In order to avoid interference with cultural values of these historical environments most likely UHI mitigation measures regard improving the thermal behaviour of the city roofs. For instance, applying white coatings on bitumen flat roofs (or replacing them by white single-ply membranes) and replacing sloped roof clay tiles by coloured tiles with cool pigments can reduce the urban heat hotspots by approximately 1.5°C. Remote sensing provides high level information that provide urban planners and policy makers with overall design guidelines for the reduction of urban heat.

Assessment of Urban Heat Island based on the relationship between land surface temperature and Land Use/ Land Cover in Tehran

In this study, the relationship between land surface temperature (LST) and Land Use/Land Cover (LULC) in Tehran Metropolitan City was studied using Landsat TM satellite image. For this, LST was calculated in accordance with the algorithm (Jiménez-Muñoz & Sobrino, 2003) and the LULC map was prepared based on supervised classification method. According to the LST map obtained by processing the thermal band of the satellite image, areas affected by Urban Heat Island (UHI) were detected to examine their status in relation to the existing LULC classes and the population density. The results showed that UHI created in Tehran are different in terms of the causative agent. This difference is primarily due to the status of LULC in the region and reflects the close relationship between land cover and land surface temperature. Also, the distribution of vegetation and green spaces in different areas of Tehran City was studied by normalized vegetation index (NDVI) using remotely-sensed data. Correlation study between the land cover and land surface temperature showed a negative correlation between these two parameters. Study of the average surface temperature in six LULC classes indicated full compliance of heat islands with LULC classes.

Assessment of urban heat islands (UHI) of Noida City, India using multi-temporal satellite data

In the present research work an integrated use of Landsat thermal data sets of year 2000 and 2013, field data and meteorological observation were used to assess the temporal changes in rising trends of urban heat island (UHI) in Noida city, India. The temperature estimation was performed on the basis of grid level analysis and compared with the land cover pattern for validation of temperature with reference to urban land use/land cover. During 2000, the total built up area was 28.17km2 which it further increased to 88.35km2 during 2013. Over the period of thirteen years from 2000 to 2013 it was observed that the built up area has increased by 26.94% of the total area (203km2). In order to study the relationship between UHI and land cover, statistical analysis was performed between temperature and Normalized Difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI), Albedo and Emissivity. The correlation between NDVI, Emissivity and temperature was negative but NDBI, Albedo and temperature showed a positive correlation. Results showed that the change in temperature was mainly due to increase in impervious areas. The results of this study will be useful to the urban planners and environmentalists in formulating local policies.

Assessing urban heat island impact on long-term trends of air temperatures in Ljubljana

The paper presents an assessment of urban heat island (UHI) impact on air temperature trends inLjubljana. The assessments are based on the comparison between the long-term air temperature trends inLjubljanaandZagreb. Meteorological station Zagreb-Gric operated on the hill in the city centre since its establishment in 1862, while theLjubljanastation changed its location several times. The analysed UHI effect on the measurements of air temperature inLjubljanagradually increased, especially after 1950.

Ocena vpliva mestnega toplotnega otoka na dolgoročne trende segrevanja ozračja v Ljubljani

The paper presents an assessment of urban heat island (UHI) impact on air temperature trends inLjubljana. The assessments are based on the comparison between thV prispevku je ocenjen vpliv mestnega toplotnega otoka (MTO) na trende segrevanja ozračja v Ljubljani. Ocene temeljijo na primerjavi dolgoročnih trendov temperature zraka v Ljubljani in Zagrebu. Meteorološka postaja Zagreb-Grič deluje od ustanovitve leta 1862 ves čas na griču v središču mesta, medtem ko se je ljubljanska postaja večkrat selila. Analizirani učinek MTO na trende temperature zraka v Ljubljani se je postopoma povečeval, zlasti po letu 1950e long-term air temperature trends inLjubljanaandZagreb. Meteorological station Zagreb-Grič operated on the hill in the city centre since its establishment in 1862, while theLjubljanastation changed its location several times. The analysed UHI effect on the measurements of air temperature inLjubljanagradually increased, especially after 1950.