1- University of Mohaghegh Ardabili
Abstract: (468 Views)
Extended Abstract
Introduction and Objectives: The phenomenon of climate change and its effects and consequences has become a challenging issue for managers and planners, especially for water resources. Currently, climate change has attracted the attention of scientists due to its effects on human societies. Snow plays an important role in the protection of biodiversity and the changes in the amount of snow cover affect animal and plant life as well as the structure of ecosystems. Snow cover is very important in mountainous areas. Since snow is considered solid water, it is an important source for providing drinking water. Because snow cover contains a lot of air, it is a weak conductor of heat, so the snow cover can protect agricultural products and trees from extreme cold. The current research aims to investigate the changes in snow cover concerning the components of land surface temperature, evapotranspiration, and vegetation cover in the Aras Basin using MODIS sensor data products in annual, seasonal, and monthly periods.
Materials and Methods: The studied area is the Aras Basin, which is considered a part of the sub-basin of the western Caspian Lake and forms the political border between the countries of Azerbaijan, Iran, Turkey, and Armenia. In this research, Terra satellite images were used to calculate snow cover, land surface temperature, vegetation cover, and evapotranspiration. In this way, for each of the mentioned variables, the annual average, monthly average, and seasonal average were calculated based on solar date. Daily products of snow, vegetation, surface temperature, and 8-day evapotranspiration product of Terra satellite were used. Finally, the images were transferred to the ArcMap 10.8 environment for calculation. To calculate the averages of the studied variables in the period of 2011-2018, using coding in Google Earth Engine, 8644, 8642, 8325, and 1058 images were processed for snow cover, land surface temperature, vegetation cover, and evapotranspiration, respectively.
Results: The results showed that in 2000-1401, the hottest and highest temperatures were in 2000, 2001, and 2014, respectively, with the average maximum temperature of 42, 40, and 40 degrees Celsius. 2017 was the coldest year of the studied statistical period with an average maximum temperature of 35 degrees Celsius and minimum temperature of 1 degree Celsius. The highest average amount of greenness was related to the years 2019 and 2021 with a value of 0.44 and the lowest average amount of greenness was related to the years 2007 and 2003 with a value of 0.34. In the studied years, 2019 had the lowest annual average of evapotranspiration, and 2022 had the highest annual average of evapotranspiration. The transpiration evaporation in 2018 was at the highest level, 20.96, and at the lowest level, 3.57 kg/m3. In 2022, evapotranspiration was 37.42 in the highest state and 2.60 kg/m3 in the lowest state. In all the studied years, the southeastern and northern parts of the studied basin have the highest average evapotranspiration. In 2018, the maximum average land surface temperature was equal to 37.12 and the minimum was equal to 0.14 degrees Celsius. In 2022, the maximum temperature of the land surface temperature was 39.80 and its minimum was 5.66 degrees Celsius. As can be seen, there has been a direct relationship between temperature and evapotranspiration in these years. During the years 2000-2022, the average NDSI in 2000 had the lowest value (17.31) and in 2017 the highest value (26.23). In all the studied years, the most snow-bearing areas were the high-altitude areas located in the southern, southeastern, and southwestern parts of the Aras Basin.
Conclusion: The results of the survey of the surface temperature maps showed that the years 2000 and 2001 started with an average maximum temperature of 42.37 and 40.20 degrees Celsius and continued with a decrease in the average maximum temperature. In 2020 and 2021, the maximum temperature reached 39 degrees Celsius, after which evapotranspiration also changed according to the land surface temperature. The trend of changes in the vegetation cover of Aras Basin generally shows an increase in vegetation cover during the 22 years, but the trend of changes in the snow cover has been a slight decrease. Higher temperatures are seen in the low and flat parts of the northeast and northwest of the Aras Basin, and lower temperatures are seen in the high areas of the southeast and west of the basin. Evapotranspiration is often observed in the northern and southeastern parts of the Aras Basin, which has more snow cover. Although these parts have higher altitudes and lower temperatures than other regions, they have more evapotranspiration. Winter and autumn are the snowy seasons of the study area. The highest amount of snow cover was in February with an area of 37234.32 square kilometers and the lowest was in August with 4.71 square meters. The high areas with snow cover (southeast, west, and north of the basin) had snow cover even in the years when the surface average snow cover was at its lowest
Introduction and Objectives: The phenomenon of climate change and its effects and consequences has become a challenging issue for managers and planners, especially for water resources. Currently, climate change has attracted the attention of scientists due to its effects on human societies. Snow plays an important role in the protection of biodiversity and the changes in the amount of snow cover affect animal and plant life as well as the structure of ecosystems. Snow cover is very important in mountainous areas. Since snow is considered solid water, it is an important source for providing drinking water. Because snow cover contains a lot of air, it is a weak conductor of heat, so the snow cover can protect agricultural products and trees from extreme cold. The current research aims to investigate the changes in snow cover concerning the components of land surface temperature, evapotranspiration, and vegetation cover in the Aras Basin using MODIS sensor data products in annual, seasonal, and monthly periods.
Materials and Methods: The studied area is the Aras Basin, which is considered a part of the sub-basin of the western Caspian Lake and forms the political border between the countries of Azerbaijan, Iran, Turkey, and Armenia. In this research, Terra satellite images were used to calculate snow cover, land surface temperature, vegetation cover, and evapotranspiration. In this way, for each of the mentioned variables, the annual average, monthly average, and seasonal average were calculated based on solar date. Daily products of snow, vegetation, surface temperature, and 8-day evapotranspiration product of Terra satellite were used. Finally, the images were transferred to the ArcMap 10.8 environment for calculation. To calculate the averages of the studied variables in the period of 2011-2018, using coding in Google Earth Engine, 8644, 8642, 8325, and 1058 images were processed for snow cover, land surface temperature, vegetation cover, and evapotranspiration, respectively.
Results: The results showed that in 2000-1401, the hottest and highest temperatures were in 2000, 2001, and 2014, respectively, with the average maximum temperature of 42, 40, and 40 degrees Celsius. 2017 was the coldest year of the studied statistical period with an average maximum temperature of 35 degrees Celsius and minimum temperature of 1 degree Celsius. The highest average amount of greenness was related to the years 2019 and 2021 with a value of 0.44 and the lowest average amount of greenness was related to the years 2007 and 2003 with a value of 0.34. In the studied years, 2019 had the lowest annual average of evapotranspiration, and 2022 had the highest annual average of evapotranspiration. The transpiration evaporation in 2018 was at the highest level, 20.96, and at the lowest level, 3.57 kg/m3. In 2022, evapotranspiration was 37.42 in the highest state and 2.60 kg/m3 in the lowest state. In all the studied years, the southeastern and northern parts of the studied basin have the highest average evapotranspiration. In 2018, the maximum average land surface temperature was equal to 37.12 and the minimum was equal to 0.14 degrees Celsius. In 2022, the maximum temperature of the land surface temperature was 39.80 and its minimum was 5.66 degrees Celsius. As can be seen, there has been a direct relationship between temperature and evapotranspiration in these years. During the years 2000-2022, the average NDSI in 2000 had the lowest value (17.31) and in 2017 the highest value (26.23). In all the studied years, the most snow-bearing areas were the high-altitude areas located in the southern, southeastern, and southwestern parts of the Aras Basin.
Conclusion: The results of the survey of the surface temperature maps showed that the years 2000 and 2001 started with an average maximum temperature of 42.37 and 40.20 degrees Celsius and continued with a decrease in the average maximum temperature. In 2020 and 2021, the maximum temperature reached 39 degrees Celsius, after which evapotranspiration also changed according to the land surface temperature. The trend of changes in the vegetation cover of Aras Basin generally shows an increase in vegetation cover during the 22 years, but the trend of changes in the snow cover has been a slight decrease. Higher temperatures are seen in the low and flat parts of the northeast and northwest of the Aras Basin, and lower temperatures are seen in the high areas of the southeast and west of the basin. Evapotranspiration is often observed in the northern and southeastern parts of the Aras Basin, which has more snow cover. Although these parts have higher altitudes and lower temperatures than other regions, they have more evapotranspiration. Winter and autumn are the snowy seasons of the study area. The highest amount of snow cover was in February with an area of 37234.32 square kilometers and the lowest was in August with 4.71 square meters. The high areas with snow cover (southeast, west, and north of the basin) had snow cover even in the years when the surface average snow cover was at its lowest
Type of Study: Applicable |
Subject:
سنجش از دور و سامانه های اطلاعات جغرافيايی
Received: 2024/02/8 | Accepted: 2024/07/22
Received: 2024/02/8 | Accepted: 2024/07/22
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