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Fu W.,CAS Institute of Remote Sensing Applications | Fu W.,Chinese Academy of Sciences | Fu W.,Nanjing University | Guo H.,Chinese Academy of Sciences | And 2 more authors.
International Journal of Remote Sensing | Year: 2010

Although the differential interferometric synthetic aperture radar (DInSAR) technique has the potential for monitoring ground deformation with millimetric accuracy, it still suffers from temporal and geometric decorrelation. In this paper, the corner reflectors differential interferometry synthetic aperture radar(CRDInSAR) technique was used to overcome the limitations of conventional DInSAR. We studied the basic principles of CRDInSAR, discussed the calculation of the flat earth and topographic phases based on the geometry of satellite and corner reflectors, presented the phase unwrapping approach for the sparse grid of corner reflectors, then investigated the construction of, and solution to, the unwrapped phase system equation. Subsequently, we applied CRDInSAR to monitor the displacement of the Shuping landslide in Hubei Province, China. In this study, we processed five SAR images on a descending pass acquired by the Environmental Satellite (ENVISAT) Advanced Synthetic Aperture Radar (ASAR) sensor from September 2005 to March 2006, and compared the achieved results of CRDInSAR with Global Positioning System (GPS) measurements at the same time ofthe SAR data acquisition assumed as reference.The result indicates a good agreement between the measurements provided by the two different techniques, which shows that CRDInSAR allows monitoring of slow landslide deformation in low coherence areas and provides accurate results. © 2010 Taylor & Francis. Source

Xu W.,Jilin University | Li C.,Jilin University | Xu M.-J.,Tianjin Chengjian University | Wu Y.-W.,Remote Sensing Center for Land and Resources | And 2 more authors.
International Geology Review | Year: 2015

The Kangqiong ophiolite is exposed in the central-western part of the Bangong-Nujiang suture zone (BNSZ) of central Tibet. This study reports new data for boninitic dikes with the aim of reconstructing the geodynamic and petrogenetic evolution of the Kangqiong ophiolite. Ten samples of boninitic dikes that cross-cut the mafic cumulates have very low TiO2 (0.34-0.42%) contents and high MgO (6.65-8.25%) contents. LA-ICP-MS U-Pb analyses of zircon from the boninitic dikes yield an age of 115 Ma. They are characterized by positive εHf(t) values varying from +13.1 to +15.0. Taking into account the geochemical characteristics of the mantle section, the Kangqiong ophiolite should be generated in a fore-arc spreading setting resulting from intra-oceanic subduction. Based on our data and previous studies, we propose that the BNSZ represents the major suture and records the Early Cretaceous intra-oceanic subduction of the Bangong-Nujiang Neo-Tethys Ocean, and the Shiquan River-Yongzhu-Jiali ophiolitic mélange belt represents a back-arc basin. These two belts, together with the northern Lhasa subterrane should, represent an Early Cretaceous intra-oceanic subduction system and back-arc basin in central Tibet that is similar to present-day active intra-oceanic subduction systems in the western Pacific Ocean. The final closure of the Bangong-Nujiang Neo-Tethys Ocean might have taken place later than the Early Cretaceous. © 2015 Taylor & Francis. Source

Wang Y.-H.,Chengdu University of Technology | Li Y.-X.,Remote Sensing Center for Land and Resources
Wutan Huatan Jisuan Jishu | Year: 2013

There are many factors to affect the helicopter TEM exploration accuracy and resolution in the actual exploration. We used the MAXWELL software to do the forward modeling to discuss the characteristics of AeroTEM system by changing the horizontal distance of the anomalous body and changing of the anomalous body angle and changing of abnormal body depth to analyze the influence of the electromagnetic response curve. The results show that the helicopter timedomain airborne electromagnetic system has a high lateral resolution and good electromagnetic responses of abnormal body morphology. Source

Luo Y.,Remote Sensing Center for Land and Resources | Xue D.-J.,Remote Sensing Center for Land and Resources
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2010

Reduction to the pole (RTP) is a standard part of magnetic data processing method, especially for large-scale mapping. RTP operation can transform a magnetic anomaly caused by an arbitrary source into the anomaly that the same source would produce if it is located at the pole and magnetized by induction only. Interpretation of magnetic data can further benifit from RTP by removing the influence of magnetic latitude on the anomalies, which is significant for anomalies caused by crust. The solution of RTP in the wave number domain faces a long standing difficulty of instability when the observed data are acquired at low latitudes especially at the geomagnetic equator. We present a new solution to this problem that allows stable reconstruction of the RTP field with a high fidelity at the magnetic equator, combining the reduction to the equator (RTE) and the phase reversal interpretation method for ΔT anomalies at low latitudes. The operation with RTE can transform theoretical magnetic anomalies located at the pole and magnetized by induction only into the observed magnetic anomalies. RTE used in our RTP procedure named SRTE is an absolutely stable potential field transformation. The principle of method is very simple, it can transform the observed magnetic anomaly at geomagnetic equator into the anomaly that would have been measured if the magnetization and ambient field were both vertical. It is a stable RTP operation at geomagnetic equator and performs a high computation speed with a reasonable accuracy. Theoretical models and the practical magnetic field data located at the magnetic equator show that the operator of RTP solution is stable and accurate. Source

Li L.,Remote Sensing Center for Land and Resources | Zhong C.,Remote Sensing Center for Land and Resources | Kong F.,China University of Geosciences
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Due to diastrophism, tide action and human activities, the coastline is always in flux. There are lots of coral islands in the south sea of China. Remote sensing survey for the coastline not only can reassert the necessity and importance of coral protection, but also can provide basic data and scientific basis for island ecologic protection, reasonable utilization of land resources. The study area named Zhao Shu Island lies in Jintong Islands of Xisha. It is a coral island which has people inhabited. Using WorldView-2 satellite remote sensing images as data sources we carry out three phases of coastline investigation and monitoring. The satellite data phases are 2002, 2010 and 2013. Firstly, affirm the bands valuable for color composition on the basis of spectral and correlation analysis. Then extract the coastline by a series of image process, such as image correction, fusion, waterline extraction and coastline revision. Finally determine the coastline types and length by artificial interpretation. The results show that the island length is gradually smaller, which means the island area is reducing. The beach bedrock coast in northern island was eroded seriously especially during the period between 2010 and 2013. In addition, the shoal head shape in the western island changed a lot. © 2014 SPIE. Source

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