Synoptic analysis and simulation of dust storm in Bahman 1395 in Khuzestan province

storm is one of the most important natural phenomena and a kind of natural disasters that influence many parts of the world. Dust storms cause many problems in different regions of Iran especially Khuzestan province every year. This province is affected by internal and external dust sources because there are some arid and semi-arid areas inside and outside of Khuzestan province especially in Iraq, Syria and Saudi Arabia countries. So a large number of studies have been done in order to analysis and simulation of dust storms. A severe dust storm has occurred in the west and south west of Iran on 7-10 Bahman 1395. The dust particles were drenched on the power transmission lines in Ahwaz city because of low precipitation on the 8th Bahman. So the electricity was cut off in the city. This event made many problems for residents of Ahwaz city. Synoptic analysis showed that, the existence of a cold front in the southeast of Iraq caused severe winds in the area on Bahman 8th. In Khuzestan province, ahead of the cold front, the south easterly winds triggered the activation of local dust hotspots located in the south of the province. The baroclinicity in the front area was quite apparent at the 850hPa level, and there was a deep height trough at the 500hPa. The output of HYSPLIT model in Khuzestan region near the surface showed the south-eastly wind flow. Also, the change in wind direction in the front area was clearly seen in the model output at 500m level. Present weather codes reported from Ahvaz synoptic station showed local and non-local dust storm and precipitation altogether. The visibility reduced under 100 meters in Ahvaz on 8 Bahman. WRF-Chem model with GOCART emission scheme was implemented for simulation of the dust event. The model outputs showed that the emission of dust particles from Iraq and south of Khuzestan was correctly simulated, and the they were in agreement with the satellite images; although the dust mass was not detected well, due to cloudiness in the region. The PM10 concentration of the model output and the measured values ​​at the air pollution monitoring stations showed that the model has a satisfactory performance in the estimation of the PM10 concentration. The model simulated the dust concentration trend correctly, however some errors in the output were seen. These errors were expected due to the complex topography of Khuzestan province. The model had a better performance in simulation of wind direction and rainfall. The model well simulated existence of the front and the sudden change of wind direction.