analyzing and mapping of dust storms seasonal frequency over iran for hazards reduction

iran is facing dust storms every year and frequently. this phenomenon has affected, especially in recent years, various aspects of people's lives. the aim of this research is iran’s seasonal clustering in terms of dust storms frequency with visibility less than 1000 and 500 m for the period of 1987–2008. for this purpose, we used the data of 87 synoptic stations that had suitable spatial distribution in country. in this research, iran was divided into 5 different regions in terms of dust storms frequency in the each season using fuzzy clustering method. stations located in these clusters are not homogeneous in terms of geographical location, climate and resources storm in different seasons of the year, but are homogeneous in terms of the visibility and intensity of storms. results indicated critical condition in terms of dust storms frequency as follows: studied stations in sistan & baluchistan, khuzestan and bushehr provinces during spring; studied stations in khuzestan province and zabol, zahedan and iranshahr (sistan & baluchistan province) during summer; station of zabol during autumn; and stations of zahedan, zabol, konarak and abadan during winter. the highest frequency of storms was observed in summer and spring, respectively, and the lowest in autumn and winter, respectively. therefore, in order to decrease weather hazards, it is necessary to run national and international plans in sistan and baluchistan and khuzestan provinces which are facing the disastor in all four seasons, with a high frequency.