The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
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Figure 1. The band model of SPOT5 data spectral characteristic 
The uplift of Tibetan Plateau changes the atmospheric 
circulation in mid-latitude westerly, forming the Plateau 
monsoon climate. The temperature is low due to the limitation 
of altitude. Therefore the average temperature is below zero in 
most area. The average temperature in the south is higher than 
that in the north at the same altitude. The annual average 
temperature is gradually reduced along the southeast to the 
northwest. The annual precipitation in Tibetan Plateau is 
relatively less and the rainfall mainly concentrated in May to 
September, accounting for 80%~95% of the annual 
precipitation. Winter is dry season and the precipitation 
occupies 5-20% of the annual. There are more thunderstorms 
and hailstone in the rainy season. In addition, Tibetan Plateau is 
the largest ice, snow and cold area in mid-low latitude region of 
the world. There is 4.7 X 10 4 Km 2 covered by glacier accounting 
for 80% glacier area in China, and frozen soil covers 150><10 4 
Km 2 . The glaciers and snow lines change regularly, while the 
distribution of frozen soil is significant different. Continental 
glaciers are distributed in the central and northern plateau, 
while oceanic glaciers are distributed in the southeast and 
southern plateau. The permafrost area is general in Kailash area 
which has continuous permafrost zone, The rest area is island 
and seasonal permafrost (Liu et al., 1997). 
The uplift of Tibetan Plateau also significantly affects the soil 
forming process and its geographic distribution. It has alpine 
soil which is the most comprehensive agrotype in China. The 
regular zonal distribution reflects that hydrothermal conditions 
gradually decrease from southeast to northwest, biological 
effect becomes weaker and soil development degree tends to 
original. The natural vertical zones are from the edge of the 
plateau to the hinterland within plateau. Along with location 
difference, the natural vertical zones have different base bands, 
their structure becomes simple, and the number of the zones 
decreases. In addition, the south of East Himalayas is one of the 
richest rainfall regions due to the impact of southwest monsoon,, 
therefore forms a vertical distributing series based on yellow 
latosol and yellow lateritie red soil. The southeast Tibet 
mountain gorge area mainly has yellow brown soil. It forms a 
vertical distributing series of which the sub-alpine grassland 
soil is the lowest level in north mid-Himalayas as well as 
upstream and middle stream area of Brahmaputra. The deep 
valleys of east Traverse-Mountains is dry and hot, therefore 
form a soil vertical distributing series of which brown soil is the 
bottom. In the eastern part of north-Tibet, the climate is clammy 
and therefore it develops as alpine meadow soil. On the plateau 
surface, the climate in south-eastern is cold and dry therefore it 
forms as alpine steppe soil. The central plateau develops alpine 
desert grassland soil. In northwest, the weather becomes drier 
and colder therefore the accumulation of the humus becomes 
weaker. The bottom layer is permafrost soil and therefore forms 
alpine desert soil (Zhang et al. 1982). 
Qixiangcuo area which lies in northern Tibet and northwest of 
Naqu region was selected as the case study area. It covers the 
area from N32° 11' to N32°41' in latitude and from E89°38' to 
E90°17' in longitude and belongs to the shuang lake special 
region which is an administrative region established in 1976 to 
develop the depopulated area in northern Tibet. This area has a 
vast territory and its residents live extremely scattered. 
Qixiangcuo area which is gentle with open grassland locates at 
Qiangtan Plateau lake basin. Its terrain is higher in the north 
than the south, and mostly are dry-cold and semi-desert 
meadows. The average altitude is about 4800m. The Kunlun 
Mountains, Tanggula Mountains, Kekexili Mountains, 
Dongbule Mountains etc. are located in this area. There are a lot 
of lakes and Qixiangcuo is one of the famous lakes (Zhang et al. 
1982; Wang et al., 2005). 
3. RS DATA PROCESSING AND INTERPRETATION 
3.1 Image data 
A SPOT5 multispectral image with 10m resolution in March, 
2004 and a panchromatic image with 2.5m resolution in 
November, 2003 were selected as the case study data for this 
interpretation task. 
3.2 Image processing 
3.2.1 Geometric correction 
In order to match the two images in the interpretation process, 
the geometric correction was adjusted first. Both of the original 
images didn’t have precise geometric correction, therefore the 
correction process was followed as below. First, the images 
were corrected separately using a reference image to unify them 
to the same geographic coordinate. Second, the two images 
were proofed by the precise geometric correction. In practical 
operation, a precisely corrected ETM image of September, 1999 
was used as the geographic reference image, polynomial model 
(cubic) was selected as the geometric correction model, and the 
nearest neighbourhood interpolation was used in resampling to 
correct two images separately. The correction results show that 
the correction errors of two images are controlled within one 
pixel. In the geometric registration, the same model used in the 
geometric correction was used as registration model, and the 
nearest neighbourhood interpolation was used in resampling, 
the registration error was also controlled in one pixel (Meng, 
2000). 
3.2.2 Image synthesis