Document Type : Research Paper

Authors

1 Graduated M.Sc. Student Faculty of Natural Resources, Tarbia t Modares University

2 Associate Professor, Faculty of natural resources, Tarbiat Modares University

3 Associate Professor, Faculty of humanities, Tarbiat Modares University

Abstract

Extended Abstract
Introduction
There has been an increase in the occurrence of dust storms in the Middle East in recent years. The World Meteorological Organization has introduced dust storms as the result of atmospheric turbulence, which injects a large amount of dust into the atmosphere and makes the horizontal visibility less than 1000 meters. Iran is involved in dust storms due to its geographical location and weather conditions. Long-term evaluation of statistical data, identifying the origin and routing dust storms can be effective in identifying the time and location of this event.
 
Materials & Methods
In this research, the temporal distribution of Khuzestan dust storms from 2000 to 2015 was investigated at five synoptic stations including Ahvaz, Abadan, Aghajari, Safi Abad and Mahshahr. Given the World Meteorological Organization’s codes on the dust storm incidents, and in order to minimize human error, the information related to the event was extracted using the Linux operating system. Furthermore, Mann-Kendall test and Pearson and Spearman correlation coefficients were used to evaluate the trend of the temporal changes of dust storms and the rate of the correlation of the effective factors with the frequency of dust storm occurrence, respectively. Regression models were used to determine the rate of the effectiveness and the prioritization of the factors affecting storms. The entire statistical analyses were performed using the SPSS 20 software.
 
Results & Discussion
According to the results obtained, out of 1507 recorded dust storms, the Ahvaz station with 509 (34%) and the Aghajari station with 156 (10%) recorded events, have had the highest and the lowest number of recorded dust storms, respectively. The temporal variations trend of dust events at the study stations was not significant at the 1 and 5% levels. However, the frequency of dusty days in the Ahvaz and Abadan stations was positively correlated with the frequency of days with the region’s prevailing wind speed and direction at the 99% confidence level (p<0.01). There was also no significant correlation between soil texture and type. The results of linear regression model showed that there is a positive relationship between the frequency of dusty days with the frequency of days with the region’s prevailing wind direction at all stations at the 99 and 95% levels. Based on the standardized regression coefficient, at most stations, the occurrence frequency of the prevailing wind at the study stations has the highest impact on the occurrence frequency of dust storms.
 
Conclusion:
About 65 percent of dust events have occurred in two cities of Ahvaz and Abadan, located in the center and southwest part of the Khuzestan province. This could be due to the further proximity of these two stations to the local and regional dust sources. Another reason could be the flow of atmospheric circulations in different regions of the province. In this regard, the northwest-southeast winds which carry dust, hit Ahvaz and Abadan more frequently. The highest number of dust storms were recorded during summer and spring. A downward trend of dust events has been observed at all studied stations since 2008. Nevertheless, the problems caused by this event have become more apparent and have affected the lives of people. For this reason, the general view is that the number of dust storm events has increased. The high concentration and the higher persistence of dust storm events could be the reason of such an idea as well. These possible causes could be addressed in future studies in analysis and control of dust storm events.
 
 

Keywords

1- رضایی بنفشه، شریفی، پیرخضرانیان؛ مجید، لیلا، سیدلقمان (1391)؛ ((برآورد میزان گرد و غبار با استفاده از تصاویر ماهواره‌ای مطالعه موردی: استان کردستان))؛ مجله جغرافیای طبیعی، سال 5، شماره 18، صص22- 13.
2- زینالی؛ بتول (1395)؛ ((بررسی روند تغییرات فراوانی روزهای همراه با توفان‌های گردوغباری نیمه‌ی غربی ایران))؛ مجله مخاطرات محیط طبیعی، سال 5، شماره 7، صص 100-87.
3- عزیزی، شمسی‌پور، میری، صفرراد؛ قاسم، علی‌اکبر، مرتضی، طاهر (1391)؛ ((تحلیل آماری-همدیدی پدیده گردوغبار در نیمه غربی ایران))؛ مجله محیط شناسی، سال 38، شماره 63، صص134-123.
4- لشکری، کیخسروی؛ حسن، قاسم (1387)؛ ((تحلیل آماری سینوپتیکی توفان‌های گرد و غبار استان خراسان رضوی در فاصله زمانی (1993-2005)))؛ مجله پژوهش‌های جغرافیای طبیعی، سال 65، شماره 17، صص 65-33.
5- میرشاهی، نکونام؛ داریوش، زری (1388)؛ ((بررسی آماری پدیده گردوغبار و تحلیل الگوی وزش بادهای گردوغبارزا در شهرستان سبزوار))؛ مجله انجمن جغرافیای ایران، سال 22، شماره 73، صص 83-104.
6. Boloorani, A. D., Nabavi, S. O., Bahrami, H. A., Mirzapour, F., Kavosi, M., Abasi, E., & Azizi, R. (2014). Investigation of dust storms entering Western Iran using remotely sensed data and synoptic analysis. Journal of Environmental Health Science and Engineering, 12(1), 124.
7. Gao, T., Han, J., Wang, Y., Pei, H., & Lu, S. (2012). Impacts of climate abnormality on remarkable dust storm increase of the Hunshdak Sandy Lands in northern China during 2001–2008. Meteorological Applications, 19(3), 265-278.
8. Goudie, A. S. (1983). Dust storms in space and time. Progress in Physical Geography, 7(4), 502-530.
9. Hahnenberger, M., & Nicoll, K. (2012). Meteorological characteristics of dust storm events in the eastern Great Basin of Utah, USA. Atmospheric environment, 60, 601-612.
10. Indoitu, R., Orlovsky, L., & Orlovsky, N. (2012). Dust storms in Central Asia: spatial and temporal variations. Journal of Arid Environments, 85, 62-70.
11. Kang, L., Huang, J., Chen, S., & Wang, X. (2016). Long-term trends of dust events over Tibetan Plateau during 1961–2010. Atmospheric Environment, 125, 188-198.
12. Kim, J. (2008). Transport routes and source regions of Asian dust observed in Korea during the past 40 years (1965–2004). Atmospheric Environment, 42(19), 4778-4789.
13. Kwon, H. J., Cho, S. H., Chun, Y., Lagarde, F., & Pershagen, G. (2002). Effects of the Asian dust events on daily mortality in Seoul, Korea. Environmental Research, 90(1), 1-5.
14. Li, N., Gu, W., & Xie, F. (2004). Threshold value response of soil moisture to dust storm: a case study of midweitern Inner Mongolia Autonomous Region. Journal of Natural Disasters, 13(1), 44-49.
15. McTainsh, G. H., & Pitblado, J. R. (1987). Dust storms and related phenomena measured from meteorological records in Australia. Earth Surface Processes and Landforms, 12(4), 415-424.
16. Mei, D., Xiushan, L., Lin, S., & Ping, W. A. N. G. (2008). A dust-storm process dynamic monitoring with multi-temporal MODIS data. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 37.
17. O’Loingsigh, T., McTainsh, G. H., Tews, E. K., Strong, C. L., Leys, J. F., Shinkfield, P., & Tapper, N. J. (2014). The Dust Storm Index (DSI): a method for monitoring broadscale wind erosion using meteorological records. Aeolian Research, 12, 29-40.
18. Ochirkhuyag, L., & Tsolmon, R. (2008). Monitoring the source of trans-national dust storms in North East Asia. Remote Sensing and Spatial Information Sciences,1(1), 835–839.
19.Rashki, A., Kaskaoutis, D. G., Goudie, A. S., & Kahn, R. A. (2013). Dryness of ephemeral lakes and consequences for dust activity: the case of the Hamoun drainage basin, southeastern Iran. Science of the Total Environment, 463(1), 552-564.
20. Rezazadeh, M., Irannejad, P., & Shao, Y. (2013). Climatology of the Middle East dust events. Aeolian Research, 10, 103-109.
21. Schepanski, K., Tegen, I., & Macke, A. (2012). Comparison of satellite based observations of Saharan dust source areas. Remote Sensing of Environment, 123, 90-97.
22. Tan, M., Li, X., & Xin, L. (2014). Intensity of dust storms in China from 1980 to 2007: A new definition. Atmospheric environment, 85, 215-222.
23. Walther, G. R., Post, E., Convey, P., Menzel, A., Parmesan, C., Beebee, T. J., ... & Bairlein, F. (2002). Ecological responses to recent climate change. Nature, 416(6879), 389-395.
24. Xiao, F., Zhou, C. and Liao, Y., 2008. Dust storms evolution in Taklimakan Desert and its correlation with climatic parameters. Journal of Geographical Sciences, 18(4), pp.415-424.