This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT technique.In this study,the freeair gravity anomalies over the South China Sea are determined by the satellite ...This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT technique.In this study,the freeair gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT,ERS1,ERS2 and T/P.And the 2.5′×2.5′ bathymetry model in South China Sea is calculated from the gravity anomalies with the inversion model given.After the analysis of the inversion and the comparison between the results,some conclusions can be drawn.展开更多
The presentation describes the methods and shows the results of GLOFs＇ danger estimation in lie and Zhetysu Alatau ranges （Kazakhstan）. The catalogues of glacial lakes were made following the results of satellite i...The presentation describes the methods and shows the results of GLOFs＇ danger estimation in lie and Zhetysu Alatau ranges （Kazakhstan）. The catalogues of glacial lakes were made following the results of satellite images processing. The catalogue contains the data of 186 glacial lakes in lle Alatau and 577 lakes in Zhetysu Alatau. According to the bathymetric data of 35 glacial lakes the dependences of volume on lake＇s area for proglacial and moraine lakes were developed and lake＇s volumes were calculated. There are 32 lakes in Ile Alatau and 110 lakes in Zhetysu Alatau with water volume more than 100,000 m3. The most hazardous lakes have the following characteristics： 1） the lake volume exceeds 100,000 m3, （2） the lake is proglacial, （3） the dam is a young moraine with an ice core, （4） there are sites with the steep of more than 15° spreading for more than 500 m down the valley, and （5） there are important non-protected objects in the mudflows affected area. There are 14 the most hazardous glacial lakes with very high level of GLOF danger： 6 lakes in lie Alatau and 8 lakes in Zhetysu Alatau.展开更多
Ice shelf breakups account for most mass loss from the Antarctic Ice Sheet as the consequence of the propagation of crevasses(or rift)in response to stress.Thus there is a pressing need for detecting crevasses’locati...Ice shelf breakups account for most mass loss from the Antarctic Ice Sheet as the consequence of the propagation of crevasses(or rift)in response to stress.Thus there is a pressing need for detecting crevasses’location and depth,to understand the mechanism of calving processes.This paper presents a method of crevasse detection using the ICESat-1/GLAS data.A case study was taken at the Amery Ice Shelf of Antarctica to verify the accuracy of geo-location and depth of crevasses detected.Moreover,based on the limited crevasse points,we developed a method to detect the peak stress points which can be used to track the location of the crack tips and to identify the possible high-risk area where an ice shelf begins to break up.The spatial and temporal distribution of crevasse depth and the spatial distribution of peak stress points of the Amery Ice Shelf were analyzed through 132 tracks in 16 campaign periods of ICESat-1/GLAS between 2003 and 2008.The results showed that the depth of the detected crevasse points ranged from 2 to 31.7 m,which were above the sea level;the crevasse that advected downstream to the front edge of an ice shelf has little possibility to directly result in breakups because the crevasse depth did not show any increasing trend over time;the local stress concentration is distributed mainly in the suture zones on the ice shelves.展开更多
文摘This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT technique.In this study,the freeair gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT,ERS1,ERS2 and T/P.And the 2.5′×2.5′ bathymetry model in South China Sea is calculated from the gravity anomalies with the inversion model given.After the analysis of the inversion and the comparison between the results,some conclusions can be drawn.
文摘The presentation describes the methods and shows the results of GLOFs＇ danger estimation in lie and Zhetysu Alatau ranges （Kazakhstan）. The catalogues of glacial lakes were made following the results of satellite images processing. The catalogue contains the data of 186 glacial lakes in lle Alatau and 577 lakes in Zhetysu Alatau. According to the bathymetric data of 35 glacial lakes the dependences of volume on lake＇s area for proglacial and moraine lakes were developed and lake＇s volumes were calculated. There are 32 lakes in Ile Alatau and 110 lakes in Zhetysu Alatau with water volume more than 100,000 m3. The most hazardous lakes have the following characteristics： 1） the lake volume exceeds 100,000 m3, （2） the lake is proglacial, （3） the dam is a young moraine with an ice core, （4） there are sites with the steep of more than 15° spreading for more than 500 m down the valley, and （5） there are important non-protected objects in the mudflows affected area. There are 14 the most hazardous glacial lakes with very high level of GLOF danger： 6 lakes in lie Alatau and 8 lakes in Zhetysu Alatau.
基金supported by the Chinese Arctic and Antarctic Administration,Fundamental Research Funds for the Central Universities(Grant No.105560GK)National Basic Research Program of China(Grant No.2012CB957704)+1 种基金National High-tech R&D Program of China(Grant Nos.2008AA121702 and 2008AA09Z117)National Natural Science Foundation of China(Grant Nos.41176163 and 41106157)
文摘Ice shelf breakups account for most mass loss from the Antarctic Ice Sheet as the consequence of the propagation of crevasses(or rift)in response to stress.Thus there is a pressing need for detecting crevasses’location and depth,to understand the mechanism of calving processes.This paper presents a method of crevasse detection using the ICESat-1/GLAS data.A case study was taken at the Amery Ice Shelf of Antarctica to verify the accuracy of geo-location and depth of crevasses detected.Moreover,based on the limited crevasse points,we developed a method to detect the peak stress points which can be used to track the location of the crack tips and to identify the possible high-risk area where an ice shelf begins to break up.The spatial and temporal distribution of crevasse depth and the spatial distribution of peak stress points of the Amery Ice Shelf were analyzed through 132 tracks in 16 campaign periods of ICESat-1/GLAS between 2003 and 2008.The results showed that the depth of the detected crevasse points ranged from 2 to 31.7 m,which were above the sea level;the crevasse that advected downstream to the front edge of an ice shelf has little possibility to directly result in breakups because the crevasse depth did not show any increasing trend over time;the local stress concentration is distributed mainly in the suture zones on the ice shelves.
