Synoptic analysis of dust events and its relation with drought in Alborz and Qazvin provinces

Dust storm is a phenomenon that mainly occurs in arid and semiarid regions in the result of high speed of wind and its turbulence on soil surface without coverage and erosion competent and cause to view amount reduction to less than 1 kilometer. In this study, dust and precipitation data in synoptic station selected in Alborz and Qazvin provinces was used during 2000 to 2014. After 06 and 07 codes extraction from meteorology data, days with dust were detected and monthly and yearly frequency of dust were analyzed statistically. evaluation of drought effect on the dust phenomena occurrence was performed using the SPI method for annual and monthly scales at 3, 9 and 18 months intervals. The drought results showed a severe drought at the Karaj station in 2013 and an extreme drought at the Qazvin Station in 2008. The result of investigation of annual dust showed that Karaj and Qazvin stations with regard to 06 and 07 codes had the highest dust phenomenon. Monthly evaluation also showed that the most frequent events occurred at the stations of Karaj and Qazvin in the months of May and June. By examining the relationship between drought and the frequency of days with dust, it was also found that there was no significant correlation between these two phenomena at the Karaj station on an annual and monthly scale, but at Qazvin Station between days with dust and SPI values in the 18-month interval, there was a weak correlation in 10% level, but there was no significant relationship between other time scales.