干旱区生态环境知识资源中心

Dust storms are one of the major environmental disasters in the arid regions of Middle East, occurring in very high frequency. As a result, monitoring dust storms and determining the aerosol concentration in the atmosphere of the Middle East are vital. The most appropriate technique in the study on dust storms is the remote sensing technique. Hence, in this study, we try to find the appropriate remote sensing techniques for the monitoring of dust storms and estimation of aerosol concentration in the Middle East. The 28 Moderate resolution Imaging Spectroradiometer (MODIS) images in the dusty days of 2008-2009 were utilized in this study. The well-known methods for monitoring dust storms using MODIS images in arid regions utilize a combination of reflective and thermal infrared bands (D-parameter), brightness temperature difference (BTD) and a normalized difference dust index (NDDI) methods. Comparing these three methods demonstrate that the D-parameter is the best method for the retrieval of dust storm from MODIS images in the Middle East. Hence, the dust storms were monitored using the D-parameter maps, retrieved from MODIS images. The relation between the visibility data (observed in 41 meteorological stations in the Middle East) and the corresponding D-parameter values could then be investigated. Processing the results showed that an exponential relation exists between them. Using the developed exponential function, the D-parameter maps were then converted to visibility maps. These visibility maps could then be classified to specific dust storm classes. Finally, using the empirical formula, the visibility maps were converted to aerosol concentration maps.