Adaptive investigation of relationship between physical indicators of the residential part and distribution of heat islands in Tabriz city (Case study: districts 2 and 8)

Introduction:Urban heat islands are one of the most common urban phenomena, and some metropolitan areas, especially city centers, are several degrees warmer than their surrounding areas. Heat islands create difficult environmental conditions for city residents and significantly impact air quality, energy consumption, and human comfort. The urban heat island phenomenon is generally studied in two ways: the atmospheric temperature of different locations is compared, and the ground surface temperature is analyzed using satellite images. Previous studies have demonstrated the usefulness of the ground surface temperature concept for measuring and estimating the amount of radiant energy emitted from the earth's surface, including areas under human construction, vegetation, wasteland, and water, which have been used in this study.
Methodology: In this study, an attempt has been made to use Landsat 8 OLI/TIRS bands initially. Using the Single Channel Algorithm (SCA), the land surface temperature was calculated for two urban districts using ENVI software. The impact of these changes on the physical indicators of the study areas, areas 2 and 8 of Tabriz, has been investigated. The indicators have been stratified in the Arc Map software environment to carry out analytical descriptions.
Results: According to the physical indicators studied, the number and shape of heat islands and the average surface temperature are higher in Region 8 than in Region 2.
Discussion: Study area and data used Tabriz metropolis is the largest city in the northwest region and the third largest city in Iran in terms of area. This city is located in East Azerbaijan province, with an area of about 25056 hectares and 38 degrees, 1 minute to 38 degrees, 8 minutes north latitude, 5 minutes to 46 degrees, and 22 minutes east longitude. In the study area, physical indicators including the total area of the residential infrastructure, the building density of the residential sector, the number of floors of the residential sector, the age of the residential sector structures, the quality of the residential sector structure, and the condition of the residential sector structure in terms of the type of building area used were selected as key indicators and examined to determine the relationship between these indicators and the distribution of heat islands in Tabriz city. In this regard, Landsat 8 OLI/TIRS satellite images were used to extract the land surface temperature. After preparing the photos, the data preprocessing stage, including geometric and radiometric corrections, was performed in the ENVI software environment to minimize the errors related to the images. Using Arc Map software, maps related to land surface temperature were examined and analyzed comparatively in regions 2 and 8 of Tabriz Municipality regarding physical indicators.
Conclusion: According to studies, the average ground surface temperature in Region 8 is warmer than in Region 2 on 05/01/2021. As shown in the tables, more buildings are older than 30 years in Region 8 than in Region 2. Since a greater number of structures in Region 8 than in Region 2 lack standard structures. In addition, the number of acceptable structures in terms of construction quality is lower in Region 8 than in Region 2. According to the statistics, structural and energy standards should be more respected in Region 8. Also, Region 8 of Tabriz has more buildings with existing masonry structures. In studies related to floors, the number of buildings up to 4 floors in Region 8 is higher than in Region 2. In addition, in Region 8 of Tabriz, the buildings have less infrastructure and higher density than in Region 2. Finally, in study area 8 of Tabriz city, parameters such as the lower height of structures, higher building density, and long life of existing structures cause an increase in ground surface temperature in the residential sector, unlike in area 2, where the buildings are taller, have a shorter structure and are older.
Therefore, it was observed that these indicators have a significant effect on the structure and formation of heat islands and the average ground surface temperature in the study areas. Based on the cases mentioned above and the fact that most of the thermal energy produced in the residential sector is transferred through convection and considering the distribution of heat islands in both areas 2 and 8, it can be concluded that the waste of thermal energy in area 8 was higher than in area 2 on the mentioned date and the existing studies in this field will contribute significantly to planning for optimizing energy consumption in areas where the necessary standards are less respected. according to all scenarios.