Study and Investigating the Effect of Meteorological Quantities on the Pollution Potential of Arak City

Introduction: Urbanization and air pollution, especially in megacities, are major issues today. Understanding the factors contributing to this problem is crucial, and reducing the associated risks is a top priority for city and country officials. Arak City in Iran is one of the most polluted cities in the country, with industrial activities being the main cause of pollution. This research aims to investigate the meteorological factors that contribute to the pollution potential of Arak City, including wind speed, temperature, pressure, precipitation, boundary layer height, vertical velocity of the atmosphere at the levels of 825, 700, and 500 mb, and air conditioning coefficient. The study ultimately confirms Arak City's reputation as one of the most polluted cities in Iran. Material and Methods: In this article, from the 20-year statistics of the Arak observation station (1380-1399) for the quantities of the earth's surface, including wind speed, temperature, pressure, and precipitation, as well as the 20-year data from 2001 to 2020, the reanalyzed data of Era5 from the database ECMWF has been used for upper-level quantities. To check other atmospheric quantities, including boundary layer height, wind speed in the upper atmosphere, and vertical wind at 825, 700, and 500 mb levels, Era5 reanalyzed data with a resolution of 0.25 degrees extracted from the ECMWF database were used. Results and Discussion: The results indicated that low temperatures in the cold period of the year, as well as low night and morning temperatures in the cold months of the year, can cause temperature inversion and increase the retention potential of atmospheric pollutants. The average wind speed indicates the low and insignificant effect of the wind, especially in the cold days of the year and in the morning and night hours. Daily per capita rainfall of less than 1 mm did not have a significant effect in reducing pollutants. The investigation of meteorological quantities in the upper levels of the atmosphere showed that the height of the boundary layer fluctuates between 200 and 1400 m daily, which was less than 400 m from late November to January. Analysis of the vertical velocity at altitudes of 825 and 700 hPa revealed a downward movement during winter, autumn, and spring, while an upward trend was noted during daytime hours in the summer season. Furthermore, a descent was observed at the 500 hPa level throughout all seasons during nighttime hours, which is not as effective as t