Investigating the effect of Madden-Julian Oscillation on the frequency of dust storms in the west of Iran.

Deserts and semi-desert countries have become increasingly affected by dust storms in recent years. In this research, the effect of the real-time multivariate of the Madden-Julian Oscillation (MJO) index on the frequency of dust storms in the west of Iran (Sarpol-E-Zahab, Islamabad Gharb, Kermanshah, and Kangavar stations located in Kermanshah province) during February-July for the period 1987-2022 and the frequency percentage of this index for Phases 7-2 (7, 8, 2 and 1) and Phases 3-6 (3, 4, 5 and 6) were investigated. The results of the analysis of the relationship between the MJO and dust storms showed that between 57 and 75% of dust storms occurred in phases 7-2 of the MJO and 25 to 42% in phases 3-6. Phases 7-2 of the MJO have a higher percentage of dust storms than phases 3-6. According to the results of the Mann-Whitney test, the displacement of phases 7-2 and phases 3-6 of the MJO have significantly led to dust storms at the Kermanshah and Kangavar stations. Due to the suitability of the HYSPLIT model for tracking dust storms, the paths of dust entering Kermanshah province were investigated with this model. Tracking the paths of dust entering Kermanshah province with the HYSPLIT model and analyzing the wind speed and direction maps of 850 hPa level indicate an increase in the speed of westerly winds. The increase in the speed of westerly winds and the decrease in soil moisture in phases 7-2 and 3-6 have caused the movement of dust particles from Iraq, eastern parts of Syria, and Khuzestan province to the studied area. [ABSTRACT FROM AUTHOR]

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