Evaluation of occurrence, tracing and origin of dust phenomenon in Zagros forest degradation monitoring sites of Chaharmahal and Bakhtiari province

Decay and drought of oak has occurred in more than 40 countries, including Iran. Numerous factors have contributed to the drought and oak decay. Among the natural causes of climate change is common in all countries, but dust has played an important role as a contributing factor to the decline of the Zagros forests, which are adjacent to and the passage of dust currents. In this study, with the aim of investigating the occurrence of dust and its direction in Zagros deterioration monitoring sites in Chaharmahal and Bakhtiari province, meteorological statistics and data of the nearest synoptic station were used. Dust event codes were extracted from 100 phenomenon codes (0-99) and the frequency of dust events with different horizontal field of view was investigated. In order to identify the direction of dust entry, the graph diagram was used and to draw the dust, WR-PLOT software was used. Data related to wind direction and speed were extracted and wind direction and speed corresponding to dust days were extracted to enter the dust drawing software and converted to a special format of this software. HYSPLIT simulation model was used to identify the source of incoming dust sources in the area of deterioration monitoring sites. The results showed that the occurrence of dust in decay monitoring sites has an increasing trend and the path of dust entering the decay sites from the west and southwest and northwest have been important, respectively. And being in the path of incoming atmospheric currents has been affected by dust mites inside and outside the country. Tracing the origin of dust particles at three altitudes of 1000, 500 and 1500 meters showed that the most important sources of dust entering the region are from Iraq and Saudi Arabia, which has been strengthened by passing through the centers of domestic dust in Khuzestan province. Considering that the occurrence of dust and its entry path can be one of the factors contributing to the decline of Zagros oak trees and the extent of its effects is different in the south-north and west-east slopes, help decision makers and planners of forest ecosystems. At the macro level, with the control programs of domestic centers and international cooperation with neighboring countries to make fruitful and fruitful efforts to preserve and rehabilitate forests.