University of Sistan and Baluchestan Journal of Natural Environmental Hazards 2676-4377 13 41 2024 09 22 Analysis of the relationship between the atmospheric thickness and the number of snow-covered days in Iran Analysis of the relationship between the atmospheric thickness and the number of snow-covered days in Iran 85 102 8288 10.22111/jneh.2024.47031.1996 FA Mohammad Sadegh Keikhosravi-Kiany Assistant professor, Faculty of Geographical Sciences and Planning, University of Isfahan, Iran Journal Article 2023 11 01 The current research aims to investigate the relationship between changes in the thickness of the atmosphere and the number of snow-covered days in Iran. For this purpose, the data of the geo-potential height values of 850, 700, 600, and 500 hpa levels were received from (ECMWF) daily and in a spatial resolution of 0.25 × 0.25 degrees of longitude and latitude for the period of 1379-1399. The thickness of the atmosphere is a variable that represents the temperature of the air layer, and the lower the thickness of the atmosphere, the lower the temperature of the air layer, and the higher the thickness of the atmosphere, the warmer the temperature of the air layer. The snow cover data of MODIS Terra and MODIS Aqua were taken daily between 1379 and 1399 and at a spatial resolution of 500 × 500 meters from the NASA website. Next, the spatial resolution of the snow cover data was changed to 0.25 × 0.25 degrees of latitude and longitude using the nearest neighbor method. The findings show that the highest values of the correlation coefficient can be seen in the winter season, so in many parts of the highlands in Iran, the values of the correlation coefficient are significant and generally less than -0.7, which indicates that the smaller values of the atmospheric thickness, the more snow-covered days throughout the country. Also, in spring and autumn, the number of cells that have a significant correlation is less than in winter. The increase in the thickness of the atmosphere over the past years in the Northern Hemisphere and Iran, which is a reflection of the increase in temperature in the atmospheric layers, can be a serious threat to the stability of snow cover, especially at high altitudes. The current research aims to investigate the relationship between changes in the thickness of the atmosphere and the number of snow-covered days in Iran. For this purpose, the data of the geo-potential height values of 850, 700, 600, and 500 hpa levels were received from (ECMWF) daily and in a spatial resolution of 0.25 × 0.25 degrees of longitude and latitude for the period of 1379-1399. The thickness of the atmosphere is a variable that represents the temperature of the air layer, and the lower the thickness of the atmosphere, the lower the temperature of the air layer, and the higher the thickness of the atmosphere, the warmer the temperature of the air layer. The snow cover data of MODIS Terra and MODIS Aqua were taken daily between 1379 and 1399 and at a spatial resolution of 500 × 500 meters from the NASA website. Next, the spatial resolution of the snow cover data was changed to 0.25 × 0.25 degrees of latitude and longitude using the nearest neighbor method. The findings show that the highest values of the correlation coefficient can be seen in the winter season, so in many parts of the highlands in Iran, the values of the correlation coefficient are significant and generally less than -0.7, which indicates that the smaller values of the atmospheric thickness, the more snow-covered days throughout the country. Also, in spring and autumn, the number of cells that have a significant correlation is less than in winter. The increase in the thickness of the atmosphere over the past years in the Northern Hemisphere and Iran, which is a reflection of the increase in temperature in the atmospheric layers, can be a serious threat to the stability of snow cover, especially at high altitudes. https://jneh.usb.ac.ir/article_8288_2145dd0cd44fb4f9a9d2e6ccc92da9a8.pdf