ANNUAL MONITORING OF DUST STORM IN IRAN AND ADJACENT AREAS USING MODIS IMAGES (1396 AND 1397 HIJRI SHAMSI)
The occurrence of dust storms is one of the major problems in Iran and neighboring countries. Monitoring dust storms and identifying their patterns, areas with high frequency of occurrence and high dense storms using remote sensing technology can help decision makers in different dimensions. This paper tries to investigate the occurrence of dust storms in Iran and adjacent regions over two annual periods, and produce the maps of cumulative density and frequency of occurrence in order to find dust patterns and hotspots and make a comparison between these periods. The daily MODIS images received at the Mahdasht Space Center in 1396 and 1397 were used. Brightness temperature images were prepared using these data and the bands 20, 29, 31 and 32 of them were used. After applying appropriate algorithms, daily dust storm maps were produced. Using the data of 212 synoptic stations throughout the country, the accuracy of the algorithms were assessed and the thresholds were modified. By combining these daily maps, annual cumulative density maps were prepared. Also, by combining daily occurrence maps of dust storms, frequency of occurrence maps were produced. The results show that in 1397, more areas have experienced dust storms in comparison to 1396. Besides, the number and density of dust storms at west and southwest areas have been reduced in 1397. Conversely, in the eastern and southeast areas we have faced with an increase in the number and density of monitored dust storms in 1397. It can be concluded that the problem of dust storms in Iran have been shifted from the west and southwest of the country to the eastern and southeastern regions.