جستجوی مقالات مرتبط با کلیدواژه « thermal island » در نشریات گروه « جغرافیا »

The purpose of this research is to investigate the relationship between these pollutions in urban areas and heat islands in Ardabil City. In this regard, the land use map of Ardabil City was drawn in the Google Earth Engine system by calling the data of Sentinel 2 and 1 satellites, and its overall accuracy and correctness were checked with the Kappa coefficient. In the next step, to investigate the aerosols of Ardabil City, Sentinel 5 satellite data was used and its daily trend was obtained by regression method. The skewness of aerosols was calculated for 2018-2023 and the pollution density map of Ardabil City was drawn. Then, by calling the MODIS satellite data, the temperature anomaly map and the thermal island of Ardabil City were drawn during 2018-2023, and the night LST trend in the mentioned period and the profile diagram of the night LST thermal island were obtained. By extracting the data of urban aerosol density maps with the thermal islands in ArcGis software, the correlation between temperature and the thermal island of Ardabil City was investigated. The results showed that there is a direct relationship between these two phenomena, such that the amount of daily aerosols in Ardabil City has taken an upward slope since the middle of 2021, and its negative skewness has shown an increase in pollution with high density and occurrence in inner city areas. The pollution density map also showed that the amount of aerosol has increased significantly in the inner city areas and intercity roads of Ardabil City. As a result, the temperature anomaly in urban and residential areas has increased significantly and led to the formation of a thermal island with an average temperature of 8.22 degrees Celsius, which reached its maximum in July.

The role of climate in the study of urban environments is important in terms of its impact on climate change in urban environments. The heat island is one of the hazards that has recently affected the environmental conditions of cities due to urban development.

For this purpose, Landsat ETM satellite images were used during the period 1990-2019. In this regard, LST and NDVI indices, urban coverage and land use were used. Geographical area of research The city of Isfahan has been considered in this study. 

Results and discussion: 

The results showed that the high temperature is mostly in the central core of Isfahan and the surrounding city is covered by the middle temperature class. Most of the low temperature class also includes agricultural use due to high humidity. Parks and green spaces in the city are among the middle temperature classes due to the impact of high and very high temperature areas around them.

In general, it can be said that in the last three periods, the highest area has been related to the average temperature, and this trend will continue in the coming years. Due to the reduction of agricultural land use and the physical expansion of the city, the area of heat islands in the upper range has increased. On the one hand, the reasons for the increase in high temperatures are the increase in population, the increase in industries and the number of cars in the city, the multiplication of traffic volumes, the increase in asphalt levels and urban and interurban roads, and the increase in wasteland due to grazing. He pointed to overcrowding and damage to pastures, as well as clearing of green lands and deforestation.

The surface temperature of the earth is one of the key parameters in the studies of cities.Air pollution is also one of the causes of the creation of heat island in the city, which has been increasing in recent years due to high population density and pollution.The aim was to investigate the temporal changes of urban heat islands and its relationship with air pollution in Kerman in a period of 16 years(2007-2022)And to investigate the trend of temperature changes, the temperature data of Kerman station and the Mann-Kendall test were used, and the data of Kerman air pollution station were used to investigate air pollution.Although the number of polluted days was high, but due to the limited passage of the Badoureh satellite for 16 days from Kerman, the limited number of days with high pollution intensity in Kerman, and the non-compliance of polluted days with the time of satellite passage, finally, seasonal images of five years were selected. The results showed that the temperature of the earth's surface had an upward trend in both seasons, but the heat island occurred only in the summer season.So that in the summer of 2009, the density of very hot temperature was less than 30%, but with the passage of time and in 2022, in the summer season, more than 60% of the urban area has very hot temperature.And parts from the west to the south of the city have formed the center of thermal islands due to the presence of barren lands and also due to the lack of benefit from evaporation and transpiration cooling mechanisms.Also, the correlation between the temperature of the earth's surface and the air pollutants was confirmed at a significant level of 0.01 and 0.05, that in the summer the correlation coefficients are stronger and pollution has also increased.

Heat waves are one of the climate hazards. The purpose of this research is to investigate the heat waves of Ardabil city and its effect on urban heating from 2003 to 2018. For this purpose by using Fumiaki index, the days where the temperature was +2 standard deviations or higher than the NTD average and lasted for at least 2 days and was defined as a day with heat wave. In order to investigate the effect of heat waves on heat island in the hot and cold months, the heat island for days with a heat wave and a normal day without heat wave with the lowest and maximum temperature before the occurrence of each heat wave during the day and at night of Modis - Aqua was calculated. According to the results, during the studied period, the highest annual and monthly frequency of heat wave in Ardabil was in 2010 and 2016 and in March, April and July. The results also showed that the maximum duration of heat waves was 4 days and therefore short-term. According to the findings, both in the hot months and in the cold months, in both heat wave and no heat wave condition, a cold island is often formed during the day and a heat island is formed at night in Ardabil center. Heat waves, especially in the hot months of the year, have been more than no heat wave conditions. In the summer nights, in the heat wave conditions, the temperature increase up to 4 ºc has also been experienced in the heat island. In total, the results showed that the influence of the heat island on the occurrence of heat waves was higher in hot months than in cold months.

Urban expansion leads to the creation of urban heat islands, which can create risks for human health and the environment. Knowledge of the state of vegetation, changes in land use and temperature of each region over time is very important and is used in micro and macro planning. Therefore, the purpose of this research is to investigate the relationship between temperature and vegetation in creating a thermal island in Isfahan city. In this regard, the use of Landsat ETM satellite images during the period of 1990-2019, LST and NDVI indices, and land use were studied and investigated. The results of the investigations show an increase in the size of the city and a decrease in the size of garden lands and marginal pastures of the city. Areas without vegetation are located in the urban area and residential areas and in the southern and eastern heights of Isfahan city. The maximum NDVI index is also in the western and southeastern areas of Isfahan city. The intensity of heat islands is more than other land uses according to the minimum and maximum level and average temperature in urban land and with the increase in the area of ​​residential uses and urban development, the intensity of heat islands has increased. On the other hand, the lowest temperature intensity of heat islands is observed in irrigated agricultural lands and gardens. In general, it can be said that in the city of Isfahan, the high temperature is mostly in the central core of the city, and the surroundings of the city are covered by the middle temperature layer. Low temperatures have also been observed in agricultural use. Parks and urban green spaces also have medium temperature classes due to their proximity to urban uses and being influenced by them. During the studied period, the largest area was related to average temperature and this trend will continue in the coming years.

In recent years, with the increase in the population of cities, urban construction has also increased and as a result, a variety of industrial activities have been developed in them. This has led to the formation of phenomena known as climate wisdom in cities, which has become a major issue in science today. Since the shapeof the organization of spaces in urban blocks plays a significant role in shaping this, so the present study examines the impact of the shape and shape of residential buildings as the most important constituent components of urban blocks. The issue concerns the formation of thermal islands. this study aims to achieve thermal comfort and reduce the effects of heat island phenomena in the space created by mid-rise residential complexes in order to Provide the optimum form of residential complexes for Shiraz. In this regard, the research method used in this article is applied research in terms of purpose and in terms of methodology, quantitative research method is used. Therefore, the research is based on two logical reasoning strategiesin one hand for analyzing library resources is used and on the other hand quantitative measurement is done by using basic form of Envi-met 4 Software. This study has analyzed and compared six different organization in the Shiraz. Hence the temperature data of 12 noon 1 July 1397 has been used as the basis for the summer revolution. The results show that the best condition at the average radiant temperature belongs to the single element central plan.

The phenomenon of Thermal Island as one of the urban hazards is the result of the way of activity and physical development of cities as well as extensive changes in the land use pattern around cities. The surface temperature of the earth is not only affected by the amount of energy received by the sun, but also by the environmental conditions of the place, especially the reduction of suburban arable land, vegetation degradation and increasing impermeability levels and potentially prone to heat production and pollution. Heated island is a term used to describe the warmer atmosphere and higher temperatures of cities compared to non-urban areas. Determining the geographical distribution and nature of UHI, as well as the factors influencing its occurrence or severity, is something that is now efficient, fast, and inexpensive using satellite imagery and remote sensing techniques. Ahvaz is one of the metropolises with ethnic diversity and mixed subcultures that has experienced a large and rapid increase in population and area over the last three decades and the city has expanded in different directions from south to southwest and north to northeast Has found. One of the prominent consequences of this issue is the emergence and strengthening of the Heated island in this city.

To determine the spatial-place changes of the heated islands of Ahvaz and also to determine its relationship with land use changes, first the Landsat satellite TM sensor images in the last 30 days and Envi software were used and the following main steps were performed:Stage 1 - Preparation of thermal map of the city: To calculate the temperature of the single channel algorithm (SCA) in order to extract LST, an extended infrared thermal band was used and to calculate it, Equation 1 was used. Ts = γ {𝜀1- (YLsensor + Ψ2) + Ψ3} + δ Here are five essential steps you can take to begin the process of preparation for mediation. To calculate each of the parameters in the equation below 5 consecutive steps as described in the headings The first step is to calculate the spectral radius The second step is to calculate the light temperature of the sensor The third step is to calculate the radiative power Step 4, calculate the values of γ and δ Step 5, calculate atmospheric parameters Stage 2: Prepare a land use map using the decision tree: The function of the model is a branch that consists of three levels of decision making and finally to determine the six layers of land cover (including agricultural land, rangeland, irrigated land, heights (Topography), land with little vegetation and built-up lands. In the model run, after applying the preprocessors to the Landsat images, the corresponding images were created for classification using NDVI, DEM, NDWI and LST indices. Setting a threshold for the NDNI index (NDVI> 0.26) vegetation is isolated from other data. In the correct branch, the next node was isolated using NDWI index (NDWI≤0.0) and determination of rangeland class threshold, agricultural land and water. In the third decision-making branch, based on the thresholds defined in the image indices (DEM≥40), DEM topography was determined, Were introduced.

Statistical study of the trend of change in land surface temperature and construction index and the ratio of change of other carabis to urban land uses showed that the trend of change is the average construction of the ascending course and the average temperature of the ascending course and the trend of changes with the transformation process With the expansion of the city of Ahvaz, their vegetation and land have been destroyed and turned into urban lands, and now the thermal island has been directed from the inside of the city to the outskirts. The temperature increase ratio of the urban area was higher than the whole study area.

Based on the results, the temperature of Ahvaz city increased from 282.96 degrees to 287.02 degrees Kelvin between 1988, which shows a growth of 2% and an increase of 4 degrees. Spatially, the highest temperature increase in the city is related to the east and southeast of the city, where agricultural lands and lands with little vegetation have been converted to industrial town and industrial uses and become a source of heat production in this metropolis. Has been. Also in the western part of the city, due to the further expansion of the city and the implementation of residential preparation projects - the NDBI index confirms the same - there has been an increase in temperature. Other influential factors in the spatial change of temperature in these parts of Ahvaz city are the existence of main roads such as Ahvaz-Abadan highway (southern part of the city), Ahvaz-Bandar Imam Khomeini highway (eastern part). Due to the asphalt cover of these routes and more vehicle traffic, they have caused an increase in the thermal map of the region. The lowest temperature in 2020 is related to the areas around the Karun River. Among the factors that have caused the low temperature in this place compared to other parts of Ahvaz in 2020, we can see the existence of the government park, Shahid Chamran University with a lot of green space and low-density residential texture and more open and green space than they  mentioned other parts of the city as well as the wetlands of the last two years. Analysis of the trend of UHI changes and increase in construction using Landsat time series images showed an increase in urban temperature compared to the surrounding area in 1988. This shift in 2020 was due to an increase in regional temperature compared to the city due to river flooding. , Increase in construction and industrial activities in and around the city. Due to the environmental dangers of the Heated island, which directly and indirectly affect urban air pollution, greenhouse gas emissions and global warming, disrupt thermal comfort, increase water and electricity consumption, and exacerbate diseases such as asthma They leave, It is necessary to prevent the change of agricultural use to urban areas, and within the city, between dense textures and industrial areas, by creating vegetation in the form of parks and gardens, tried to prevent the rise in surface temperature.

Investigating the micro-climatic conditions of the city based on data from professional meteorological stations reveals more tangible realities from the urban heat island. In this study, urban heat island was analyzed based on hourly and daily temperature data of automated air-polluting stations under the supervision of Isfahan Municipality's Air Monitoring and Control Center. The validity and accuracy of the data of these stations were confirmed by the correlation and graphical test with the data of the Meteorological Organization's ozone meter station at 99% confidence level. Then the thermal island of the city was obtained based on the temperature difference between the urban and suburban surfaces. The results showed that the annual mean of the thermal island was UHIA = -1.27, indicating no thermal island formation at the annual scale. The minimum heat island in summer is UHIS = -1.55 and the maximum in winter is UHIW = 0.96. Thus, only in winter the average temperature in the city is higher than in the suburbs. Investigation of circadian temperature regime at urban and non-urban levels showed that city temperature at night is higher than the peripheral environment due to higher concentration of urban pollutants due to lower night temperature and temperature inversions especially in cold season. However, due to the reflection of more urban surfaces, the surface temperature of the city is lower than the surrounding environment. Thus, the urban island occurs seasonally in the cold season and in terms of day and night changes. Locally, the isotherm of the urban thermal island is denser and more prominent, mainly in the east and northeast of Isfahan, and the center of the thermal island is concentrated in the northeast of Isfahan.

Studying the spatial pattern of thermal islands with satellite imagery is one of the major challenges in the urban development process of developing countries. If this growth is dispersed and unplanned, many problems and problems will arise in the management and urban planning process.  The purpose of this study is to identify the distribution and temperature difference of different regions of Qom city with respect to its suburbs in order to discover thermal islands and to map its temperature. In this study, using remote sensing and Landslide and OLI and TIRS satellite imagery during six consecutive months from January 1979 to June 1398 cold months to hot months, we investigate the LST surface heat distribution in Qom and its lands. Its margin was scattered in relation to the use and NDVI vegetation index factor. During the research, it is suggested that the thermal islands in Qom be prevented by preventing the destruction of agricultural fields and the construction of urban parks in the desert and open urban areas.

Urban heat island refers to an area where the temperature is higher than of the surrounding environment. It is referred to as an island since the temperature of a point or an area of the earth's surface (the city) is more than of the surrounding environment, which mostly has, a homogenous and uniform temperature. Therefore, this island, which can be separated and distinguished from the surrounding environment of the city, is named the city of heat island. Urban heat island can be due to growing population and its concentration in the urban centers, and consequently the increase in air pollution. Changes in land use can be regarded as one of the underlying causes of the occurrence of urban heat island. For example, using satellite images to study the heat island in the city of Mashhad, by Mousavi Bayeghi et al. (2012) showed that along with the land use change from the garden level to the city one, there has been a rise in the temperature. Frequent pollution in the city of Isfahan in recent years has led to the development of some hypotheses assuming some relationship between urban heat island and pollution. In this regard, the growing population density and the vertical expansion of the city, as well as urban development, have resulted in the development of the idea that the study of urban heat island in relation to air pollution can be very important as it can help cope with and decrease the degree of urban heat island. With this objective in mind, this study is designed to address this important concern.
The growing intensity of the thermal island due to air pollution in addition to the undesirable effects on human health can seriously damage the valuable historical works in the popular tourist city of Isfahan. It is hoped that the results of this research could help reduce the effects of the thermal island, leading to the development a better living environment in the city of Isfahan accordingly. Methods based on Satellite images can be regarded as one of the best ones for studying the thermal island; in fact, such methods have been used in many studies inside and outside the country. In this research, the thermal island in the city of Isfahan has also been analyzed using satellite imagery. In order to study urban heat island in the city of Isfahan, a series of landsat 8 satellite images with good resolution were used. This satellite conducts imaging through 11 spectral bands. The bands 1 to 9, which are known as OLI, carry out imaging in color and NIR spectra. The bands 10 and 11 are well-known as TIRS thermal bands. They do imaging within long infrared waves. In this study, the bands 4, representing red, and 5, representing the near-infrared, and the thermal bands 10 and 11 were used to study the urban island in the city of Isfahan. The data related to AQI air quality index was used to check days with air pollution. Due to the restrictions over the passage of satellite within a period of 16 days over the city of Isfahan, the limited number of days with extremely high pollution in the city, and the non-conformity between polluted days and the time of satellite passage, images of three days representing the very unhealthy (the red condition), unhealthy (the orange condition), and healthy (yellow condition) air were thus used. In this study, Subrino Split-Window algorithm was used as the technique to calculate the Earth's surface temperature. This method is based on the calculation of brightness temperature of the bands 10 and 11 as well as the vegetation index of the bands 4 and 5. For this purpose, Arc_GIS10.3 software was used to compute the Earth's surface temperature and the air temperature of the city. ENVI software was also used for the atmospheric correction. Isfahan, due to climatic conditions and a flat topography, has a relatively quiet atmosphere throughout the year. Although Mount Soffeh is located in the south-west of the city, this mountain can only help reduce the speed of westward winds over the city as it is a single peak with a low height. In addition, the vertical expansion of buildings in all parts of the city causes the wind speed to be slow due to the increased friction. High buildings with greater height than the other points, especially in the western part of Isfahan, have led to the considerable reduction of wind speed, which is an important parameter. On the other hand, population growth and its concentration in the central part of the city have increased the intensity of urban heat island. To address the possible relationship between air pollution and urban heat island, the date of January 22nd, 2014 was chosen for investigation. On this day, the temperature calculated from satellite images of the city was within the range of 3 and 17 degrees Celsius. In general, the temperature fluctuated between 5 and 9 ° C in most parts of the city, and the 7° C isotherm bypassed most parts of the city.
The correlation coefficient between vegetation index (NDVI) and land surface temperature, LST, was equal to the 0/37064, which was significant at the confidence level of 99%. Given that the urban heat island is based on urban atmospheric temperature, not the temperature of emitting or reflecting surfaces, some empirical relationships were used to convert surface temperature to air temperature. Accordingly, it was found that the air temperature in the city fluctuated between +5.5 and -1.8 ° C on January 22nd, 2014.
The comparison of the city thermal island map with the map of pollution distribution confirmed the increase in the city temperature as a result of urban air pollution.
That is, the highest concentration of pollution in the East and North East of related to the areas with the higher air temperature. The observed maximum temperature shown by the color red in the map was 13.8 degrees and this was 10.6 degrees in the suburbs. Temperature difference between the city heat-island and suburban areas on this days reached to 3.2 degrees Celsius.
The highest rates of pollution were observed in the stations located in the Eastern Isfahan, including the Ahmadabad SQ and Kharazi Highway. Correlation analysis between the earth's surface temperature map and the map of the distribution of air quality index in the city of Isfahan showed a correlation coefficient of 0.242 at 99% confidence level on January 22nd, 2014. On this day, air pollution AQI index was between 117 to 169, and the temperature ranged from 8.5 to 13.7 degrees Celsius. The city of Isfahan, due to stable climatic conditions at most times of the year and the spread of pollution, is one of the most polluted cities in Iran. The increased intensity of thermal island is one consequence of this phenomenon. In this study, Landsat 8 satellite images with a high resolution were used to estimate the surface temperature of the Earth. The temperature calculated by the model was compared with the soil temperature at the meteorological stations. A slight difference between the temperature in soil at the depth of 5 centimeters and the LST obtained through satellite images, which ranged from a maximum of 6 to a minimum of 1.8, showed that the Subrino's Split Window method could be suitable for estimating the surface temperature of the earth. Finally, the urban heat island in the city of Isfahan was obtained based on the statistical relationships between the land surface temperature (LST) and the air temperature. The analysis of topographic profile related to thermal island temperature showed the promotion of the thermal island in the city as compared with the surrounding area. That is, the temperature inside the city was 7.3 degrees and 9.5 degrees Celsius warmer than the surrounding area respectively, which could show the city's urban heat island clearly. The difference between the temperature of the city's thermal island and the city's surrounding temperature was higher at the time of the maximum pollution. The comparison of the temperature maps of Isfahan with the pollution distribution maps revealed the maximum correlation between temperature and the pollutant areas. The correlation coefficient between the pollution distribution map and the urban temperature map was positive and significant. In more polluted days, the linear relationship between the pollution increase and urban air temperature increase was stronger. As a result of the increased air pollution, the intensity of the thermal island of the city was aggravated. The study of air pollution distribution in the city of Isfahan showed that the eastern regions had more contamination. This was influenced by the urban topography. This is because the southern and western parts of Isfahan are at a higher elevation due to the presence of Mount Soffeh, and the pollution due to mass weight tends to subside in the lower northern and eastern regions of Isfahan. On the other hand, pollution is more concentrated in the eastern regions of the city due to the slow prevailing western winds. The comparison of the thermal map of the thermal Island in the city of Isfahan to the pollution distribution map confirmed the effect of pollution on the increase of urban air temperature. Therefore, the most pollution was concentrated in the eastern and northeastern Isfahan, which were the areas with the higher air temperature. The observed maximum temperature reached to 13.8 degrees, whereas it was 10.6 degrees in the suburbs of Isfahan.

This article was conducted in order to gain more knowledge about thermal differences (Thermal Island) between Tehran and Karaj based on a five-year statistical period (1993-1997). The element of temperature as the most important climatic element has been obtained as daily minimum and maximum from the Meteorological Organization of Iran. In the study of thermal island, stations of Dushan Tappeh in the east, Aqdasieh in the north and Mehrabad in west of Tehran, as the most important study area and Karaj station in west of Tehran as complementary area, have been selected. Based on the investigations carried out on the average temperatures of three stations in Tehran and Karaj station, it was observed that Dushan Tappeh as the most important thermal region in Tehran has the highest temperature values ​​for both minimum and maximum annual temperatures with temperatures 13.33 and 22.49 ° C, respectively. Next, Mehrabad station has been determined as the second thermal zone in Tehran with the minimum annual temperature of 12.88 ° C and 12.29 ° C at maximum temperatures. Third, Aqdasieh station, with a mountainous character and higher elevation than the rest, acts as a relatively weak thermal zone, the average annual minimum temperature at this station being 10.33 and the maximum temperature 19.9 ° C. Generally, the mean annual temperatures of all three stations in Tehran have higher temperature values ​​at both minimum and maximum temperatures than Karaj station, so that Tehran has a temperature difference of more than 0.75 ° C in the mean annual maximum temperature and a temperature difference of 3.37 ° C at the average annual minimum temperature with Karaj, and so has been recognized as the warmer region.

The centers in which most human activities and fumes from pollutants, cars, and … are accumulated and appear as nodes in urban environments, form thermal islands. The heat generated by these islands, in addition to increasing energy consumption due to cooling, causes pollution in the atmosphere, including production of ozone gas and increase of other harmful compounds of carbon and sulfur. Considering the mentioned issues, the present study attempts to introduce and recognize the pollutants in the Ahwaz city environment, examine their effect on the creation of thermal islands and also explain and propose strategies for their prevention, such as specialization of urban planning, prevention of mass construction, etc.

In this paper, the concept of Thermal Island has been discussed in general. First of all, the definition of the city’s thermal island and its history have been presented using illustrations and diagrams. Next, the climate variables affecting thermal islands have been considered. The purpose of the research is to introduce the city’s thermal island or the point of maximum of heat in the city, which mostly includes the city center. The term “thermal island” refers to the fact that city is warmer than its suburbs and surrounding area, which in some cases can show in a difference in temperature of 5-8 ° C. The research method in the paper is documentary, secondary and with the help of utilization of electronic sources and various websites. In addition, the hypothetical factors that create the cap layer covering the city’s thermal island are mentioned, and the radiation level in the urban area, its comparison with the suburbs and the effects it has on human health and the environment have been studied. Finally, strategies for dealing with Thermal Island through improving public behavior in relation to protecting the environment, developing green space, etc. have been examined and proposed.