Document Type : Research Paper

Authors

• Mohammadreza Rafighi ¹
• Mehry Akbary ²
• Mohammad Hassan Fakharnia ³
• Mohammad Hassan Vahidnia ⁴

¹ Kharazmi University

² Associate Professor, Faculty of Geographical Sciences, Khwarazmi University

³ MSc in Remote Sensing and GIS, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran

⁴ Assistant Professor, Department of Remote Sensing and GIS, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran

Abstract

Introduction
Although the air layer adjacent to the earth's surface - the boundary layer - is a small fraction of the entire atmosphere, the processes that take place on a small scale are very important to human life and activites. Among living organisms, plants and especially trees have undeniable effects on surface temperature and especially in urban environments have several balancing effects. This research was carried out using Landsat 8 satellite imagery and with      Arc GIS software to compare the surface temperature of the earth in two areas with vegetation of coniferous trees (Chitgar Park) and broadleaf trees (Shahid Chamran Park).
 
The values ​​of Radiance, Reflectance, Brightness Temperature, Normalized Difference Vegetation Index, Proportion of Vegetation and Emissivity and then Land Surface Temperature were calculated and generated. A total of 1700 points were harvested from Chitgar Park and 800 points from Chamran Park. In SPSS software, Leven test (F) statistics was used to prove the homogeneity of variances of the samples and parametric tests (T with two independent samples) were used to prove the significant difference between the surface temperature of the earth in the mentioned areas. According to Leven test, the value was Sig = 0.409 (P_value), which confirms the homogeneity and equality of variance of the studied samples. Also, in the T test, the value was Sig = 0.000, which is less than 0.05, which means a significant difference. Therefore, the difference between the surface temperature data of the two parks was proved. Also, by comparing the graphs of LST values ​​in the two groups, we found that Chitgar Park has a higher surface temperature than Chamran Park. In the current dilemma of the century, global warming, knowing these local realities and providing logical solutions to reduce surface temperature at the regional and regional scales as a whole can effectively solve the problem of global warming on a global scale.
Data and Method
          The data used in this study is a Landsat 8 satellite imagery with the acronym: 8 (LC08_L1TP_165035_20190706) is LANDSAT.
Retrieved July 6, 2019 from the USGS website.
Production of component images for Shahid Chamran Parks in Karaj and Chitgar in Tehran:
     The surface temperature image was generated step by step using the Landsat 8 satellite image using the Raster Calculator command in the ArcMap software environment. First, relevant and effective indicators in calculating the surface temperature of the earth, Top of atmospheric radiance, reflectance, Brightness Temperature, normalized difference vegetation index, proportion of vegetation, emission coefficient (emissivity), calculation and their images are produced and then the land surface temperature, It was calculated and produced according to the following mathematical formulas.
Step 1: Produce a spectral radius image from above the atmosphere
           To obtain the brightness temperature, the image must first be converted to radius. Therefore, the gray DN values of bands 10 and 11 of the Landsat 8 satellite TIRS sensor should be converted to high atmospheric radius separately with the help of the MTL file, which is an extension of the Landsat image (Tables 1, 2 and 3).
Formula (1) :Calculate the radius of the upper atmosphere
 TOA (Lλ) = ML * Qcal + AL
Lλ = (Watts / (m2 * srad * μm)) The radius of the atmosphere in terms of
ML = Multi-band radius_ 10 band
Step 2: Produce an image of the light temperature above the atmosphere
      After converting the DN values of bands 10 and 11 to high atmospheric radii, we converted these two corrected bands to Brightness Temperature.
BT = (K2 / (ln (K1 / L) + 1)) - 273.15     Formula (2): Calculation of Brightness Temperature BT = Atmospheric Brightness Temperature (° C)
Lλ = (Watts / (m2 * srad * μm)) Radius of the atmosphere in terms of
BT = (1321.0789 / Ln ((774.8853 / “% TOA%”) + 1)) - 273.15
K1 = K1 Constant Band (No.), K2 = K2 Constant Band (No.)
Step 3: Produce vegetation index image
      formula (3): normalized difference vegetation index image was generated using
NDVI = (Band 5 - Band 4) / (Band 5 + Band 4)
Step 4: Produce a proportion of vegetation image
The proportion of vegetation image was generated using normalized difference vegetation index.
formulas (4):Calculate the proportion of vegetation
PV = (NDVI - NDVImin / NDVImax- NDVImin) 2
PV = Square (("NDVI" - 0.216901) / (0.632267 - 0.216901))
Step 5: Produce the Emissivity image
      Emissivity image was generated using formula (5)
ε = 0.004 * PV + 0.986                Formula (5): Calculate the Emissivity coefficient
Step 6: Produce an image of the earth's surface temperature
      Land surface temperature image was generated using formula (6).
Formula (6) :Calculate ground land surface temperature
LST = (BT / (1 + (0.00115 * BT / 1.4388) * Ln (e)))
Results and Discussion
     Text Comparison of surface temperature phenomena (LST)
          According to Table (6), the highest land surface temperature with 44.42 ° C belongs to Chitgar Park, which is covered with coniferous trees, and the lowest in Shahid Chamran Park, in Karaj with 28.09 ° C with broadleaf trees. Has been. According to Tables (7) and (8), the lowest temperature of Chamran Park is 28.09 ° C and the highest is 36.51 ° C and the lowest temperature of Chitgar Park is 34.74 ° C and the highest is 44.42 ° C. . According to Figure (22), Chitgar Park with an average surface temperature of 38.92 ° C is warmer than Shahid Chamran Park with an average land surface temperature of 31.39 ° C. Figure (23) shows a red graphic showing the surface temperature of the ground in Chitgar Park with coniferous species (pine) and the blue diagram shows the surface temperature of Shahid Chamran Park in Karaj with broadleaf species. It is clear that the temperature is significantly higher in Chitgarh Park. The range of temperature fluctuations in Shahid Chamran Park is between 36.51 - 28.09 ° C and in Chitgar Park is between 42 / 44-74 / 34 which is exactly shown in the diagram. The fact that the red chart is higher than the blue chart explains this correctly. This is due to the lower density of trees in Chitgarh Park as well as the predominant tree species (needle-shaped) due to less shading and more input radiation.
     T test with two independent samples:
          This test, which is a parametric test, was used to prove a significant difference between the earth's surface temperature in areas with coniferous and deciduous trees. Leven test (F) was used to prove the homogeneity of sample variances and t-test with two independent samples was used to examine the homogeneity of the means of the two statistical populations, which resulted in the following results. As can be seen in Table (12), the value = 0.409 Sig, which is the same value as P_value, is greater than 0.05, ie the variance of the communities is homogeneous and equal. 0.05 is less, which means that the difference is significant. Due to religion, the difference between the land surface temperature data of Shahid Chamran and Chitgar parks is proved.
Conclusion
According to all the findings, Chitgar Park has a higher land surface temperature than Chamran Park, which is due to the lower density of trees and also the type of dominant tree species (needle-shaped). Coniferous species that take up less space than broadleaf species and have less shading. They also make it possible for the sun to collide with the ground due to the fact that the leaves of the adjacent trees do not meet, and this is an important factor in raising the surface temperature in the mentioned park. Species compatible with the climate of the study areas are broadleaf species because they have more leaves shading and care than coniferous species and ultimately cause more climate adjustment. The difference in temperature between the two parks confirms this fact. In the current dilemma of the century, global warming, knowing these local realities and providing logical solutions to reduce surface temperature at the regional and regional scales as a whole can effectively solve the problem of global warming on a global scale.            

Keywords

• broadleaf"
• coniferous"
• land surface temperature"
• "
• Shahid Chamran Park "
• . "
• Chitgar Park"

Main Subjects

• Climatology