'eijing 2008 
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
967 
1, 17, 2006, 
rid land. 
re difference 
jur regions: 
jects, ground 
st storm was 
wavelength, 
tion of cloud 
rd band of 
the seventh 
e among the 
normalized 
Lafatos,2006) 
id and snow 
l the seventh 
NDDI > 0 can be used to remove the influence of cloud. band can be used to remove the influence of water, and then, the 
However, the reflection of water is close to 0 at the seventh twenty-sixth band is used to detect cloud, 
band. If there is water, NDDI>0 cannot get a perfect result. So 
the influence of water should be removed firstly. The seventh At nighttime, there is no reflectance information, so the 
temperature of 11pm is used. The concrete process has been 
showed in figure 3: 
(a) 
(b) 
Figure 3.The concrete process for dust storm detection :(a) at daytime ;(b)at nighttime. 
2.2 The Intensity Grades of Dust Storm Estimation 
Based on the extracted scope of dust storm, dust storm can be 
estimated as strong dust storm, medium intensity dust storm, 
weak dust storm. Because dusts particles emit and radiate, 
backscattering solar radiation at the shortwave infrared band, 
the twentieth band,, the brightness temperature of dust storm at 
this band is especially high and the band is very sensitivity to 
reflect the blowing sand and strong dust storm.. Comparing 
images of all the channels, it can be found easily that at the 
twentieth band, the color of dust storm areas is obviously light, 
but at the other bands, that is dark. At the thermal infrared band, 
the thirty-first band, dusts particles only emit and radiate 
electromagnetic wave, so values of sensors are lower. So the 
brightness temperature difference between the twentieth band 
and the thirty-first band can be used to estimate the intensity 
grades of dust storm. 
4. CASE STUDIES 
A dust storm process occurred in the northwest of China on 
April, 16-17, 2007.According to the dust storm dynamic 
monitoring process, four MODIS images are chosen to monitor 
the scope of dust storm, its intensity and its moving trace,. 
Result shows dust storm occurred in mid west of Inner 
Mongolia province and Mongolia, and its central area is in the 
middle of Inner Mongolia province (see figure 4(b)), then 
moving to the east, influencing Gansu, Shanxi, Hebei, Tianjin, 
Shandong provinces, while its intensity changes form weak to 
strong(see figure 4(d)(e)(g)). In order to verify the method put 
forward in this paper and compare with the monitoring results, 
the 1,4,3 bands are chose to synthesis true color images(see 
figure 4(a)(c)(f)), As shown in the true color images, the top 
construction of dust storm area is uniform, having texture along 
with wind, unclear in boundaries. At the desert area, larger sand 
dune can be discriminated. At the cloud area, especially at 
medium, altostratus cloud area, the height of different clouds 
distinct greatly, texture scattered, irregular in boundaries. The 
monitoring result at night (see figure 4(e)) cannot be compared 
to the true color images, but it is consistent with the monitoring 
result of meteorological department. The monitoring result of 
meteorological department shows: dust storm happened in 
middle of Inner Mongolia on March, 26, and dust storm also 
happened at the Hexi Corridor of Gansu, in the mid east of 
Inner Mongolia, in the north of Ningxia, on March, 27 
According to images in this period, the moving trace of dust 
storm can be monitored: dust storm happens at the west of Inner 
Mongolia, the north of Gansu, on April, 16, then moving to 
Shanxi, Hebei, Tianjin, Shandong, influencing Bohai Sea. Its 
central area moves from west to east. 
5. CONCLUSION AND FUTURE WORK 
In this paper, Terra and Aqua satellite data are combined to 
describe the dust-storm moving trace. According to the dust