نویسندگان
دانشگاه یزد، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Sabzevar city is one of the favorable places for the frequent occurrence of dust phenomenon in the northeast of the country. In this research, the temporal and spatial analysis of the dust phenomenon was carried out using hourly data of wind direction and speed and the current and past weather conditions during the twenty-year statistical period of 1387-1367. Using the View WRplot software, the annual snowstorm of the Sabzevar synoptic station was drawn. Since Golbad specifies the wind condition in general and does not specifically give us information about dust-producing winds, in this article a new diagram is introduced, which we called Dust Flower. The dust cloud shows the classification and distribution of the direction and speed of dust-producing winds (dusts) in a certain period. Gol Gharb diagram was drawn annually and monthly for Sabzevar synoptic station and then its results were compared with Golbad diagrams of the city. In addition, a new quantity named Brind radius was added to these diagrams. This radius makes the comparison of Golbad and Gol Ghbar faster and easier. The statistical results of this research show that during the statistical period under study, the occurrence of days with dust in Sabzevar city has an increasing trend, and the most likely occurrence is in the months of May and June, and in more than 71% of the cases, in the hours after It happens at noon. The prevailing wind in Golbad and Golghar annual diagrams is east. Also, winds blow in 85.4% and dust in 81.36% during the year in the east-west direction and have created a wind channel in this direction in the region, this result is completely consistent with the topography of the city. The average speed of the winds was estimated at 8.75 m/s, and 50% of them have a speed of more than 9 m/s. A detailed study of the monthly dust clouds proves the influence of different atmospheric systems in the formation of this phenomenon in the region. With the increase of the sun's radiation from May to September and due to the presence of vast plains and deserts around Sabzevar, thermal systems dominate the region and the prevailing wind direction is east, but from October to May, at the same time as western systems enter the region and The blowing of strong winds on the surface of the earth is reduced from the abundance of eastern winds and added to western and southwesterly winds, so that the prevailing wind direction in Golbad Bahman of this month is east, but the prevailing wind direction in Gul Gharbar of this month is completely western. Comparing Shua Brind in different months of the year confirms this trend. These studies can be used to control the origin of dust feeding as well as the natural planning of the region.
کلیدواژهها [English]