Document Type: Original Article

Authors

1 Assistant Professor, Geography department, Payame Noor University, Tehran, Iran

2 Assistant Professor, Payame Noor University, Tehran, Iran

Abstract

The direction and speed of winds play an important role in the occurrence of pollutions and dust stormas well as location placement for the establishment of industries and the expansion of cities. Yazd is a dry area of Iran, and constantly exposed to the dust particles in the air; and this in terms of human life and health issues are of special importance. In this paper a day when due to the amount of dust particles visual acuity reduces to 5,000 m is considered the dusty day. In this study dusty days and direction and wind speed of 4 synoptic stations were studied in spring 2010. Pearson correlation has been used in the study of relationship between wind direction and speed and the occurrence of dust. The results show a direct correlation between wind direction and speed, the wind direction nearer to 360°, (North) wind speed increases. There is an inverse correlation between the speed and the visibility in dusty days, where in 17 cases this relationship has been significant up to confidence level. Of course, in 5 cases the calculated correlation is negative. So according to the obtained results. there is an inverse relation between speed and visibility in stormy days, so that with increased wind speed visibility is reduced. Although the test does not show a significant correlation between wind speed and Visibility, due to a direct correlation between wind speed and wind direction from one side and the reverse relationship between two components of speed and visibility it can be said that whatever wind direction gets close to the North, in high speed winds visibility reduces.

Keywords

Andreae,M.A., (1996); Raising dust in the greenhouse. Nature 380, 389-390.
Dehghanpour A., 2005, Statistical Analysis and synoptic days with dust in the central plateau of Iran between 2000-1990, Ph.D thesis. Tarbiat Moallem University of Tehran.
Goudie,A.S., Middleton, N.J., (2001). Saharan dust storms : nature and consequences , Earth – Science Reviews 56: 179-204.
Hemmati, N., 1995,Frequency of dust storms in Central and South West regions of the country, Geophysics, Tehran University, MA thesis.
Hosseini, Bagher, 2000, Study of synoptic extreme storms Tehran, Tehran University,.
Idso,S., and Brazel, A.,(1977); Planetary radiation balance as a function of atmospheric dust: climatological consequences. Science 198,731-733.
Idso,S.B.(1976); Dust storms. Scientific American 235(4): 108-11.113-14.
Khosravi, Abbas, wind analysis of Kashan and applying it to stabilize sand dunes, Sepehr, period VII, No. 27.
Koch, J., Dayan, U., (1992). A synpotic analysis of the meteorological conditons affecting dispersion of pollutants emitted from tall stacksin the coastal plain of Israel .Atmos .Environ ., 26A.2537-2543.
Li, X., Maring, H., Savoie, D., Voss, K., Prospero, J.M.,(1996); Dominance of mineral dust in aerosol light scattering in the north Atlantic trade winds. Nature 380, 416-419.
Littmann,T., (1991); Dust storm frequency in Asia: climatic control and variability. International Journal of climatology 11, 393-412.
Marjani, Sydsdraldyn investigate synoptic winds in excess of 15 meters per second, Khorasan,
Marjani, S., 1993, Synoptic Study of Severe Winds More than 15 m/s (Storm) in Khorasan Thesis of Meteorology (Synoptic) for the Degree of M.A, Tehran University.
Mershahi , Darius and Nekoonam brocade, 2009, Geography, No. 22.
Nekoonam, Z., 2008, Analysis of Dust Storms in Sabzevar City, Thesis of Physical Geography (Climatology) for the Degree of M.A, Yazd University.
Omidvar, K., 2005, The Study and Synoptic Analysis of Sand Storms in Ardakan-Yazd Plain, Geographical Research of Yazd University, pp. 215-225.
Saaroni,H., Ziv.B., Bitan.A., &Alpert.P.,(1998).Easterly Wind Storms over Israel, Theor.Appl.Climatol.59:61-77.
ShigoingWang,Jinyan Wang, ZijiangZhou.Kezhengshang,(2005).Regional characteristic of three kinds of dust storm event in China. Atmospheric Environment 39:509-520.
Ta-Hsiung,L., (2001). Long-range transport of yellow sand to Taiwan in Spring 2000: observed evidence and simulation, Atmospheric Environment 35:5873-5882.
Tegen, L., fung, L., ,(1995); Contribution to the atmospheric mineral aerosol load from land surface modification. Journal of Geographical Research 100, 18,707-18,726.
Tegen, L., fung, L.,(1994); Modeling of mineral dust in atmosphere: source transport and optical thickness. Journal of Geographical Research 99, 22,897-22,914.
Tegen, L., Lacis, A.A., Fung, L.,(1996); The influence on climate forcing of mineral aerosol from disturbed soil. Nature 380, 419-422.