چکیده:
images. In the first step, windy conditions of the Sistan plain were analyzed using wind statistics data. Next, five
stormy days of Zabol city, indicating different wind speeds and horizontal visibilities during those storms, were
selected. Then, high temporal resolution MODIS data was used as appropriate satellite data in this study. After that, a
storm index was defined by means of analyses of storm radiance profile in bands with maximum and minimum storm
reflection. The index is the square of difference between visible and thermal infrared bands, which is able to segment
stormy confines with the range of reflection changes between 0 and 16. The reflection values were segmented in
center of a 1 km2 network using usual interpolation methods such as Local Polynomial, Radial Basis Function,
Inverse Distance Weighted, Ordinary Kriging and Universal Kriging. In order to assess the above mentioned
interpolation methods, validation techniques were applied using ArcGIS 9.2 software. The result of these assessments
such as standard deviation method indicates that the Ordinary Kriging had lower standard deviation. By analyzing the
variograms and spatial analysis of the data using GS+ software, the best mathematic model able to fit the points was
selected and classification was done by using this model. Finally, the stormy corridors with different dust densities
were determined and by calculating the area and determining the villages located in these corridors, the critical
regions were recognized. In this study the data from visible bands (4 and 9) and thermal band (21) of the MODIS
sensor shows better results compared with the other bands, to segment and classify relative density of dust storms.
Moreover, variographic analysis of the satellite data indicates that in most of the dust storms, power models with
spherical threshold is the best for interpolation.
خلاصه ماشینی:
ir DESERT 17 (2013) 193-202 Determining Area Affected by Dust Storms in Different Wind Speeds, Using Satellite Images (Case Study: Sistan Plain, Iran) M.
Goharib a Associate professor, Yazd University, Yazd, Iran b MSc. Graduate, Yazd University, Yazd, Iran Received: 2 March 2011; Received in revised form: 4 July 2011; Accepted: 30 October 2011 Abstract The aim of this study is to determine the area affected by dust storms in different wind speeds using satellite images.
In this study the data from visible bands (4 and 9) and thermal band (21) of the MODIS sensor shows better results compared with the other bands, to segment and classify relative density of dust storms.
2. Selection of satellite data In the present study, stormy days were selected based on wind speed and horizontal visibility (HV) values of dusty days of Sistan plain.
6. Extraction of digital number of images and investigation of data distribution normality In the present study, calculated IVDI values for all pixels (with special resolution of 1 km) were used to analyse spatial correlation and determining optimal model to apply appropriate weight factor for interpolation.
In the present study the data from visible bands (4 and 9) and thermal band (21) of the MODIS sensor presented better results, comparing to other bands, to segment and classify relative density of dust storms.
M. 2005, The study on detachment and origin of dust storms on Sistan plain by use of satellite images.