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Guo J.,Shandong University of Science and Technology | Guo J.,Key Laboratory of Surveying | Sun J.,Shandong University of Science and Technology | Sun J.,Huaihai Institute of Technology | And 3 more authors.
Acta Geodaetica et Cartographica Sinica | Year: 2010

Satellite altimetry is an important technique to monitor the lake level variations. About 10 years of TOPEX/Poseidon altimetric data which have been corrected, edited, reduced and filtered, have been used to compute the time series of lake levels at Bosten Lake in the west China. The time series is analyzed with the Fourier transform and the wavelet transformation, respectively. The mean periods are 1 034 d,363 d,182 d and 47 d. The seasonal variation is the main component, and the amplitudes of the annual and semiannual are 0. 719 6 m and 0. 532 2 m respectively based on the least square approach. So the annual is the dominant period of the seasonal variation, and the semiannual is the minor period. The trend of the water level variation of Bosten Lake is 0. 201 2 m/a, which indicates the water level of Bosten Lake is rising under the effect of global warming. Then the correlation between the NIN03 SST and the water level variations of Bosten Lake is analyzed. The correlation is maximal ( - 0. 278 4) when NIN03 SST has occurred about 6 months, which indicates El Niño has a lagged influence on the climate in the west China.

Zhang G.,Wuhan University | Zhang G.,Satellite Mapping Applications Center | Qiang Q.,Wuhan University | Zhu X.,Satellite Mapping Applications Center | Tang X.,Satellite Mapping Applications Center
Acta Geodaetica et Cartographica Sinica | Year: 2010

SAR image ortho-rectification in the areas where it is difficult to select points, such as hilly and mountainous terrain, often adopts the method based on the image simulation. The traditional method used the RD model to do the simulation but it needed to establish different modules to do the simulation and ortho-rectification for different SAR images. This paper proposed the method using the RPC model substituting the RD model to simulate the SAR image in order to address the problem and did the ortho-rectification with the simulated image. Also, this paper improved the method of obtaining gray information from the simulated SAR image. TerraSAR-X images acquired over Sichuan were used as test data. Through the comparision between the actual accuracy and the theoretical accuracy of the ortho-rectification image, the theory and method proposed in this paper were verified.

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