Trend analysis of number of dusty days in Iran

In this study, annual changes in number of dusty days in Iran over the period of 1965–2005 (41 years) wre investigated. Mann-kendall test, spearmans-Rho test and Autocorrelation test were applied to quantify the trend. Mann-kendall and spearman's test showed similarity in the results, in compared with Autocorrelation test. This study reveals that the all studied stations showed a trend, but among them, only 26 trends were significant statistically, at Mann-Kendall test (16 stations had decreased and 10 stations had increased trend). Spearman’s Rho was significant for trends at 27 stations (17 stations with a decrease and 10 stations with an increase in trend). The autocorrelation test results shows, 33 stations had significant positive or negative trends. The most decreasing and lowest slope was in Abadan and Tabriz stations with values -1.92 and -0.1, respectively. The most increasing and lowest slope was in Iran shahr and Gorgan stations with values 1.97 and 0.8 respectively.