# Regional Analysis of Dust Day Duration in Central Iran
## 3 Results  
### Regional Homogeneity Test  
For the regional homogeneity test in this study, the maximum annual duration of dust days of 35 synoptic stations in the central plateau of Iran was investigated and the maximum duration of dust days in each year was used for frequency analysis. The first step in regional frequency analysis is to identify homogeneous regions. In a homogeneous region, the set of stations should be approximately similar in terms of frequency distribution. The homogeneous region is the main unit of regional frequency analysis. In homogeneous areas, the area does not need to be geographically homogeneous, but the stations should have similar values. Figures 3 and 4 show the linear moments and homogeneity diagrams of the area.  
Figures 3 and 4 show the linear moments diagrams for the stations in the area. As shown, these moments have good dispersion around the mean.  
Moreover, the D statistic was used to ensure the absence of heterogeneous stations in the region. Table 2 shows the calculations of descriptive statistics and sample linear moments for the stations under study. As shown in the table, the value of the D statistic in all stations is less than 3 and indicates that there is no heterogeneous station in the region. The value of the H statistic (less than 1) also supported the conclusion that the region is completely homogeneous.  
Figure 3: Diagram of linear moments L\(-\)CV, L\(-\)CS of the studied stations, along with those expected from different candidate probability distributions.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**D** & **LCk** & **LCv** & **LCs** & **Station Name** & **Station Number** \\ \hline
1.19 & 0.230 & 0.310 & 0.250 & Anar & 1 \\ \hline
1.55 & 0.348 & 0.508 & 0.5 & Bam & 2 \\ \hline
1.70 & 0 & 0.532 & 0.225 & Jiroft & 3 \\ \hline
1.53 & 0.323 & 0.564 & 0.505 & Kahnooj & 4 \\ \hline
1.12 & 0.144 & 0.459 & 0.263 & Kerman & 5 \\ \hline
0.78 & 0.064 & 0.443 & 0.234 & Shahdad & 6 \\ \hline
0.6 & 0.150 & 0.401 & 0.269 & Sirjan & 7 \\ \hline
0.04 & 0.160 & 0.464 & 0.299 & Shahrbabak & 8 \\ \hline
1.55 & 0.384 & 0.509 & 0.501 & Ardestan & 9 \\ \hline
1.65 & 0.124 & 0.434 & 0.254 & Isfahan & 10 \\ \hline
1.23 & 0.345 & 0.356 & 0.265 & Khoor.Biabank & 11 \\ \hline
1.12 & 0.256 & 0.214 & 0.567 & Naeein & 12 \\ \hline
0.87 & 0.154 & 0.456 & 0.354 & Natanz & 13 \\ \hline
1.18 & 0.321 & 0.785 & 0.2457 & Shahreza & 14 \\ \hline
1.23 & 0.298 & 0.458 & 0.286 & Kabootaabad & 15 \\ \hline
1.98 & 0.287 & 0.443 & 0.2632 & Arak & 16 \\ \hline
0.65 & 0.253 & 0.469 & 0.321 & Mahalat & 17 \\ \hline
1.34 & 0.215 & 0.346 & 0.324 & Saveh & 18 \\ \hline
1.25 & 0.145 & 0.765 & 0.354 & Ghom & 19 \\ \hline
1.12 & 0.186 & 0.745 & 0.435 & Salafchegan & 20 \\ \hline
0.67 & 0.196 & 0/561 & 0.406 & Semnan & 21 \\ \hline
1.77 & 0.229 & 0/422 & 0.298 & Zabol & 22 \\ \hline
0.43 & 0.397 & 0.453 & 0.501 & Zahdan & 23 \\ \hline
1.64 & 0.389 & 0.478 & 0.568 & Aghda & 24 \\ \hline
1.32 & 0.204 & 0.786 & 0.451 & Yazd & 25 \\ \hline
1.26 & 0.101 & 0.763 & 0.397 & Marvast & 26 \\ \hline
1.87 & 0.158 & 0.298 & 0.374 & Sabzevar & 27 \\ \hline
0.56 & 0.274 & 0.444 & 0.313 & Birjand & 28 \\ \hline \end{tabular}
\end{table}
Table 2: Descriptive statistics and linear moments of station DDD.  
Figure 4: Diagram of linear moments L\(-\)CK, L\(-\)CS of the studied stations.