بررسي مناطق برداشت ذرات گردوغبار و ويژگي هاي انتشار آنها در طوفان هاي منطقه سيستان با استفاده از پردازش تصاوير ماهواره اي

Investigation of dust origins and characteristics of their spreading in Sistanʹs storms, Iran region, using image

This study has done to determine the origin of dust storm and spreading of dust using satellite image processing. Since dust storms occur in large area and can transport a lot of dusts in long distances, large-scale repeatable images were needed. Besides the above-mentioned specification, the MODIS sensor from TERRA satellite receives long wavelengths of electromagnetic, which can be used to meet the purposes of this study. Five images of MODIS taken in 2001 were used in this project to meet the above purposes. An image of Landsat taken in 2001 was also used to prepare NDVI.The measurements on the images of dust storm showed that the directions of dominant winds in Sistanʹs dust storm are between 339 to 346 degrees. These directions coincided with the directions of erosive winds in Zabol synoptic meteorological station. Visual interpretation on the origin and the storm ways of dust storm showed that the dust storm starts over Hamoon Sabory Lake, and long passageways with heavy dust are separated from light dust, and to continue towards Iran, Afghanistan and Pakistan. These passageways seem like cones the head of which are at the origin and the bases towards the opposite direction. On the other hand, the extracted Normalized Difference Vegetation Index (NDVI) with its high values (0.24) of it was showed condensed vegetation in southern shores area of Sabory Lake. The comparison between the spectral signature of samples with heavy and light dust showed that, it had a little variation with each other. But afterwards, the passageways with heavy and light dust were formed.