Introduction: Many countries encounter dust storms phenomenon that is one of the meteorological problems leading to many disturbances. Materials and methods: Although the dust storm is historically recorded as an old event in some provinces of Iran, but it becomes a new event in some parts such as Ilam province. Results: After statistical investigation of dust storms in Ilam province, the dust storm from 3td to 6th July 2016 are studied. The source of this dust storm was the eastern areas of Syria and central Iraq base on the satellite images, the outputs of HYSPLIT and WRF-Chem models. Conclusion: Model outputs in intensity of surface dust concentration of MACC-ECMWF, NASA-GEOS, NCEP-NGAC, NMMB-BSC, and BSC-DREAM8b models are compared to the observation data in Ilam city and results show that NASA-GEOS model has better performance. In display of dust dispersion on Iran, the middle of all models is more compatible with reality.

Introduction: The entry of dust particles into water areas, which has increased sharply in recent years, causes a lot of environmental damage. The Persian Gulf and the Gulf of Oman are among the water areas that are covered with dust many times of the year. Materials and methods: In this study, a severe dust from July 27 to 31, 2018 is analyzed, in which a large part of the Persian Gulf, Oman Sea and the western part of the Indian Ocean was involved. To study this phenomenon from different perspectives, satellite products, visibility from synoptic stations and synoptic maps were analyzed and the output of two numerical dust models of United States National Aeronautics and Space Administration-Goddard Earth Observing System (NASA-GEOS) and Dust Regional Atmospheric Model with 8 categories-Monitoring Atmospheric Composition and Climate (DREAM8-MACC) were examined. To qualitative and quantitative evaluate of the model outputs, the Aerosol Optical Depth (AOD) of TERRA/MODIS was used. Results: Satellite imagery shows that in this case study, parts of the Persian Gulf and the Sea of Oman were affected by dust, and on July 30, dust particles entered the western half of the Indian Ocean. Comparison of model outputs with satellite data resulted that both models underestimate the AOD values, especially over water, and do not show well the entrance of dust particles into the eastern part of the Persian Gulf, the Gulf of Oman and the western half of the Indian Ocean. Conclusion: Qualitative and quantitative comparison of AOD output of the two models with satellite data showed that the NASA-GEOS model had better performance and its output correlation with observational data was higher.