基于多尺度学习型字典表示的极地浅层探冰雷达图像去噪算法

为了更好地解决极地浅层探冰雷达回波信号中的杂波和噪声问题,提出了一种基于多尺度学习型字典表示的极地浅层探冰雷达图像去噪算法。该算法首先通过曲波变换构建曲波系数矩阵,在曲波域使用自适应字典学习得到原子尺寸不同的多尺度字典,最后利用去噪和修正后的曲波系数重建浅层探冰雷达剖面图像,完成最终的去噪。结果表明:相较于曲波变换去噪算法、K-SVD(K-奇异值分解)去噪算法,改进的算法不但能够有效地去除噪声,提高图像的峰值信噪比,而且探冰雷达图像的边缘轮廓信息得到了较好的保留,有着良好的视觉效果。

近期国际冰盖模式比较计划回顾及启示

南极冰盖和格陵兰冰盖是当代仅存的两大冰盖,其冰量分别约为58 m和7 m海平面当量。极地冰盖的质量变化对全球海平面上升和气候变化有着直接和间接的重要影响。建立可靠的大陆冰盖数值模式是定量研究冰盖动力过程的唯一有效手段。过去数十年来,极地冰盖模式发展已经取得了长足的进步,但其内在的数值系统偏差是影响模式推广的重要限制因素。

Internal layering structure and subglacial conditions along a traverse line from Zhongshan Station to Dome A,East Antarctica,revealed by ground-based radar sounding

During the 21st Chinese National Antarctic Research Expedition(CHINARE 21,2004/05),a radar dataset was collected using a ground-based radar system,along a traverse line from Zhongshan Station to DT401(130 km from the Kunlun station).The internal layering structure and subglacial conditions were revealed along the radar profi le.Continuous internal layers,disturbed layers,and echo-free zones(EFZs)along the profi le were identifi ed and classifi ed,and the spatial distribution was presented.Based on recent surface ice velocity data,we found that the internal layers at a depth of 200-300 m in the upper ice sheet are continuous,smooth,and nearly parallel to the ice surface topography.In addition,the thick band of continuous layers changes little with increasing latitude.At depths below 300 m,the geometric structure of the internal layers and the vertical width of the EFZ band are infl uenced by the surface ice velocity and bed topography.The relatively high disturbance,layer discontinuity,and larger EFZ band width directly correspond to a higher surface ice velocity and a sharper bed topography.In particular,we found that at a depth of 650-950 km,the Lambert Glacier Rift in the Gamburtsev Mountains has a higher ice fl ow;moreover,the revealed internal layers are disturbed or broken,and the maximal vertical width of the EFZ band most likely exceeds 2000 m.

对阿尔金断裂问题的研究现状的浅析

阿尔金断裂是青藏高原的西北边界,分隔了塔里木与柴达木盆地,是新生代中亚大陆内一条重要的走滑断裂带。其在青藏高原演化及大陆动力学中的研究意义不言而喻,目前已成为中,外地学界瞩目的研究热点。断裂发生的时间、方式、速率及规模等是阿尔金断裂问题的研究焦点。本文将对近年来阿尔金断裂焦点问题的不同观点做浅要的归纳和评述,认为阿尔金断裂的活动具有多期次性,其对柴达木盆地与塔里木盆地的沉积构造起着重要的作用,因此未来10年,随着能源短缺以及一带一路的深入,阿尔金断裂的隆升年代学研究、断裂对两侧盆地的控制作用及指导油气勘探将引起更多人的关注。