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APPLICATION OF NOISE REDUCTION METHOD BASED ON CURVELET THRESHOLDING NEURAL NETWORK FOR POLAR ice radar DATA PROCESSING

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Journal of Electronics(China) 2013年第4期30卷 377-383页

作者： Wang Wenpeng Zhao Bo Liu Xiaojun Key Laboratory of Electromagnetic Radiation and Detection Technology Chinese Academy of Sciences University of Chinese Academy of Sciences

Due to the demand of data processing for polar ice radar in our laboratory, a Curvelet Thresholding Neural Network (TNN) noise reduction method is proposed, and a new threshold function with infinite-order continuous derivative is constructed. The method is based on TNN model. In the learning process of TNN, the gradient descent method is adopted to solve the adaptive optimal thresholds of different scales and directions in Curvelet domain, and to achieve an optimal mean square error performance. In this paper, the specific implementation steps are presented, and the superiority of this method is verified by simulation. Finally, the proposed method is used to process the ice radar data obtained during the 28th Chinese National Antarctic Research Expedition in the region of Zhongshan Station, Antarctica. Experimental results show that the proposed method can reduce the noise effectively, while preserving the edge of the ice layers.

关键词： radar data processing Thresholding Neural Network (TNN) Curvelet ice radar

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ice radar investigation at Dome A, East Antarctica:ice thickness and subglacial topography

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Science Bulletin 2010年第Z1期 425-431页

作者： CUI XiangBin1,2, SUN Bo2, TIAN Gang1, TANG XueYuan2, ZHANG XiangPei2, JIANG YunYun2, GUO JingXue2 & LI Xin21 Department of Earth Science, Zhejiang University, Hangzhou 310027, China 2 Polar Research Institute of China, Shanghai 200136, China

Dome A, located in the central East Antarctic ice sheet (EAIS), is the highest summit of the Antarctic ice sheet. From ice-sheet evolution modeling results, Dome A is likely to preserve over one million years of the Earth's paleo-climatic and -environmental records, and considered an ideal deep ice core drilling site. ice thickness and subglacial topography are critical factors for ice-sheet models to determine the timescale and location of a deep ice core. During the 21st and 24th Chinese National Antarctic Research Expedition (CHINARE 21, 2004/05; CHINARE 24, 2007/08), ground-based ice radar systems were used to a three-dimensional investigation in the central 30 km×30 km region at Dome A. The successfully obtained high resolution and accuracy data of ice thickness and subglacial topography were then interpolated into the ice thickness distribution and subglacial topography digital elevation model (DEM) with a regular grid resolution of 140.5 m×140.5 m. The results of the ice radar investigation indicate that the average ice thickness in the Dome A central 30 km×30 km region is 2233 m, with a minimal ice thickness of 1618 m and a maximal ice thickness of 3139 m at Kunlun Station. The subglacial topography is relatively sharp, with an elevation range of 949-2445 m. The typical, clear mountain glaciation morphology is likely to reflect the early evolution of the Antarctic ice sheet. Based on the ice thickness distribution and subglacial topography characteristics, the location of Kunlun Station was suggested to carry out the first high-resolution, long time-scale deep ice core drilling. However, the internal structure and basal environments at Kunlun Station still need further research to determine.

关键词： Antarctica ice sheet Dome A ice radar ice thickness subglacial topography deep ice core

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Structure of the internal isochronous layers at Dome A,East Antarctica

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Science China Earth Sciences 2011年第3期54卷 445-450页

作者： TANG XueYuan SUN Bo ZHANG ZhanHai ZHANG XiangPei CUI XiangBin LI Xin Ocean University of China College of Marine Environment Qingdao 266100 China SOA Key Laboratory for Polar Science Polar Research Institute of China Shanghai 200136 China

Dome A (Kunlun Station) is considered a likely place for finding an ice core record reaching back to one million years. The internal isochronous layering of the Antarctic ice Sheet, revealed by ice radar, is a prerequisite for selecting sites for deep ice core drilling that can be used for studying the paleoclimatic record. In 2004/2005, during the 21st Chinese National Antarctic Research Expedition (CHINARE 21), a 200-km long, continuous radar profile was obtained across Dome A. The internal layers along the profile were derived from the stratigraphy detected by the radar. The morphology of the isochronous layers shows that: (1) The internal layers in the shallow ice sheet (0-500 m) are generally flat, with no more than 50 m of layer intervals, and have typical synclines and anticlines in some localized regions. (2) At 500-2000 m below the surface of the ice sheet, the layers appear as 'bright layers', and the width of the layer intervals expands to 50-100 m. (3) When the basal topographic wavelengths are approximate to the thickness of the ice (3 km), the traced internal layers, with localized bumps or concave folds, are asymptotic parallel to the subglacial topography. For the longer topographic wavelengths (~20 km) wider than the thickness of the ice, the layers do not rise and fall with the basal topography. The internal layers surrounding some mountain peaks representing the most extreme variation in the terrain are sharply disturbed by the subglacial topography. (4) Layer discontinuity and fracture were detected in the basal ice sheet. Finally, by combining this new information with that derived from existing data regarding ice thickness, we were able to select three potential sites for reconstructing the age-depth relationship of the ice core.

关键词： East Antarctic ice Sheet Dome A ice radar internal layers deep ice core

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