Lambert冰川流域物质平衡和南极冰盖变化

对Lambert冰川流域的现场考察资料和浅冰芯研究结果显示,该流域东侧和西侧积累速率分布和过去几十年的变化具有明显差异:东侧平均积累速率较西侧高;近50年东侧处于增加状态,西侧则为明显减小.冰量平衡计算表明,该冰川流域目前处于物质正平衡状态,因而冰盖将趋于增厚.据现有资料估计分析,整个南极冰盖处于微弱负平衡.如果南极地区气候变暖,物质平衡将向正平衡方向发展,因而不会引起海平面上升.但是西南极冰盖的不稳定性可能随气候持续变暖而增强,成为引起海平面上升的最重要潜在因素.     

基于无人机技术的藏东南帕隆4号冰川表面高程和运动速度变化研究

应用无人机技术,采用后差分测量（post processed kinematic,PPK）方法替代传统控制点的方法,对藏东南帕隆4号冰川消融区进行了航测,获得了2017—2018年3期高精度正射影像（DOM）、数字表面模型（DSM）和三维点云数据;分析了该冰川航测区内表面高程变化、运动速度空间差异和冰川微地貌特征等. 结果表明:PPK测量技术应用效果良好,无人机产品水平和垂直精度分别约为0.11和0.17 m;帕隆4号冰川消融区表面高程变化量呈现随海拔升高而降低的空间分布规律,冰川冰体整体减薄4.06 m;冰川表面运动速度随海拔升高而增大,呈现冰川中流线区域略快于两侧的空间分布特征;冰川表面地貌特征随海拔由高到低呈现趋于“平滑”的变化规律. 此外,还探究了无人机技术在冰川变化研究中的潜力,为未来利用无人机开展更大范围冰川变化的研究提供了有益经验.      

科学家首次绘制南极冰川运动地图

科学家绘制的地图显示,有大量的冰川正在以每年800英尺(约244米)的速度从南极向南冰洋移动。科学家最近首次成功地绘制出了南极冰块运动地图,这一突破在未来对海平面上升情况进行跟踪时将起到巨大作用。该研究项目是由来自美国加州大学欧文分校的埃里克·里格洛特(Eric Rignot)教授负责的。     

我的南极科考之旅

正作为中国第30次南极科考队中年龄最大、我国开展极地考察30年来的首位贵州籍科考队员,在近5 0天的科考之旅中,贵州师范大学副校长谢晓尧教授将带给我们哪些关于南极的故事呢?身穿中国红,出发2013年12月12日上午11点,登上由贵阳飞往北京的CZ6187航班——这,是我参加中国第30次南极科考项目的起点。连续一周的行囊准备,心情变得不是出征前的兴奋,而是担扰极地诸多未知因素的忐忑。     

基于多源遥感影像的南极Lambert流域冰川运动速度提取与精度验证

冰川运动速度是计算极地物质平衡和对冰盖和冰架数值模拟的重要参数.针对传统冰川运动速度提取算法的不足和局限,基于差分干涉技术(DInSAR)和多孔径干涉技术(MAI)开展二维冰川运动速度的提取研究.将该算法应用于南极Lambert流域冰川运动速度的提取,得到了研究区域高精度的二维冰川运动速度场,将采用偏移量跟踪算法提取的冰川运动速度和本文提取的冰川运动速度进行了对比分析和精度评价;结合研究区域已有历史观测数据,分析全球气候变化背景下Lambert流域冰川的动态变化.研究结果表明,基于DInSAR和MAI的冰川运动速度提取算法优于偏移量跟踪算法;近20年的冰川运动速度时间序列数据显示Lambert流域的冰川运动速度基本处于稳定状态.     

基于时序偏移量跟踪技术的喀喇昆仑山Batura和Passu冰川表面流速监测

基于2017-2019年Sentinel-1 SAR数据,利用小基线集(SBAS)偏移量跟踪技术获取喀喇昆仑山系Batura和Passu冰川时序表面流速,分析冰川表面流速时空变化特征.结果表明,Batura和Passu冰川都表现出明显的季节变化特征.Passu冰川对季节响应存在异常现象,春冬季节的强降水增强冰川表面流速...     

基于无人机遥感技术的港湾养殖区监测

无人机(unmanned aerial vehicle,UAV)遥感具有高时效、机动灵活、高分辨率的特点,探索应用UAV遥感平台对沿海养殖区进行监测,实时掌握养殖发展动态,开展灾后应急监测,显然具有重要意义.利用UAV获取的CCD相机光谱信息,建立渔排监测指数,提出了渔排监测指数阈值快速提取算法;并针对渔排本身混合了水体和木筏2种目标物的特性,对提取结果进行图像闭合算子运算.在福建沿海古雷和可门港的实验结果表明,基于UAV获取的数据影像,利用渔排监测指数快速提取算法估算的渔排面积精度在两个区域分别达到98.9%和97.4%,与传统遥感分类方法——最大似然法相比,在同一计算平台上,计算速度提高5倍,无论精度或速度都可满足海洋与渔业管理部门在业务上的快速响应需求.此外应用UAV,以苏迪罗台风过后的三都澳海区为例,尝试开展了台风灾害造成的渔排损毁分析,初步推算出台风造成的渔排损毁面积比例.该研究表明利用UAV遥感可以为渔业管理提供有效的技术支持.     

无人机低空遥感技术在道路安全监测及修复中的应用

随着遥感技术的不断发展,利用当今流行的无人机,可以方便快捷地采集地表信息。无人机低空遥感技术应用在道路安全方面具有一定的现实意义,它可以为广大车主提供安全警示,为道路监管部门提供辅助决策。通过对道路影像的采集、处理、计算和分析,找出存在安全隐患的路面障碍物,识别路坑,通过数字测图系统,计算路坑的半径大小和深度,根据不同的车速预判事故风险,为道路安全监测提供科学依据;同时,为已破坏的道路提供修复方案,估算修复所需材料数量,做到有的放矢,节约资源,提高效率。实验结果证明,通过无人机低空遥感技术,既可以为行车安全提供科学预判信息,又可以为道路修复提供相对准确的所需材料用量。     

中国天文学家奔赴南极建设极地天文观测站

中国南极天文中心的天文专家2008年11月12日随同中国第24次南极科考队出征南极,筹建极地天文观测站,并为建立南极天文台而努力。     

无人机遥感技术在测绘工程测量中的应用

在测量和测绘工程领域,运用无人机进行遥感探测,不仅极大地提高了测量的效率和质量,还增强了现场作业的安全性,同时有效减少了整体的测绘成本。基于此,文章从无人机遥感技术及其应用优势分析入手,论述了测绘工程测量中无人机遥感技术的应用,期望通过此次研究能够对无人机遥感技术在工程测量领域中的推广普及有所帮助。     

南极海冰厚度数值模拟

主要进行南极地区海冰厚度的数值模拟研究,并考虑太阳短波辐射等因素对南极海冰厚度变化的影响。根据我国第22次南极科学考察现场观测数据,建立了辨识海冰厚度的最优控制模型,并用遗传算法求解该最优控制问题,仿真结果与现场观测数据吻合良好,表明所建模型和求解算法是准确有效的。     

基于实测冰芯数据的南极海冰厚度的数值模拟

根据我国第22次南极科学考察现场观测数据以及现场采集的冰芯分析数据,考虑太阳辐射、云量等因素对南极海冰厚度变化的影响,利用最小二乘法辨识气温与冰表面温度之间的关系,并以辨识结果所得到的冰表面温度作为上边界条件,依据实测情况取结冰点-1．81℃作为下边界条件,对一维热传导方程采用Crank-Nicolson格式进行离散,对南极中山站内拉湾附近海域海冰厚度变化进行了数值模拟,并与现场观测的海冰厚度数据进行了对比。     

Eight glacial cycles from an Antarctic ice core

The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long--28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.     

Switch of flow direction in an Antarctic ice stream

Fast-flowing ice streams transport ice from the interior of West Antarctica to the ocean, and fluctuations in their activity control the mass balance of the ice sheet. The mass balance of the Ross Sea sector of the West Antarctic ice sheet is now positive--that is, it is growing--mainly because one of the ice streams (ice stream C) slowed down about 150 years ago. Here we present evidence from both surface measurements and remote sensing that demonstrates the highly dynamic nature of the Ross drainage system. We show that the flow in an area that once discharged into ice stream C has changed direction, now draining into the Whillans ice stream (formerly ice stream B). This switch in flow direction is a result of continuing thinning of the Whillans ice stream and recent thickening of ice stream C. Further abrupt reorganization of the activity and configuration of the ice streams over short timescales is to be expected in the future as the surface topography of the ice sheet responds to the combined effects of internal dynamics and long-term climate change. We suggest that caution is needed when using observations of short-term mass changes to draw conclusions about the large-scale mass balance of the ice sheet.     

Antarctic ice-sheet loss driven by basal melting of ice shelves

Accurate prediction of global sea-level rise requires that we understand the cause of recent, widespread and intensifying glacier acceleration along Antarctic ice-sheet coastal margins. Atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves, potentially limiting their ability to buttress the flow of grounded tributary glaciers. Indeed, recent ice-shelf collapse led to retreat and acceleration of several glaciers on the Antarctic Peninsula. But the extent and magnitude of ice-shelf thickness change, the underlying causes of such change, and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted. Here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum-Antarctic pattern of ice-shelf thinning through increased basal melt. We deduce that this increased melt is the primary control of Antarctic ice-sheet loss, through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow. The highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf. Wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of Antarctic ice shelves, through ocean upwelling in the Amundsen and Bellingshausen seas, and atmospheric warming on the Antarctic Peninsula. This implies that climate forcing through changing winds influences Antarctic ice-sheet mass balance, and hence global sea level, on annual to decadal timescales.     

Antarctic ice sheet GLIMMER model test and its simplified model on 2-dimensional ice flow

The three-dimensional finite difference thermodynamic coupled model on Antarctic ice sheet, GLIMMER model, is described. An idealized ice sheet numerical test was conducted under the EISMINT-1 benchmark, and the characteristic curves of ice sheets under steady-state was obtained. Based on this, this model was simplified from a 3-dimensional one to 2-dimensional one. Improvement of the difference method and coordinate system was proposed. Evolution of the 2-dimensional ice flow was simulated under coupled temperature field conditions. The results showed that the characteristic curves deriving from the conservation of the mass, momentum and energy agree with the results of ice sheet profile simulated with GLIMMER model and with the theoretical results. The application prospect of the simplified 2-dimensional ice flow model to simulate the relation of age-depth-accumulation rate in Dome A region was discussed.     

Antarctic ice sheet GLIMMER model test and its simplified model on 2-dimensional ice flow

The 3-dimensional finite difference thermodynamic coupled model on Antarctic ice sheet, GLIMMER model, is described. An idealized ice sheet numerical test was conducted under the EISMINT-1 benchmark, and the characteristic curves of ice sheets under steady state were obtained. Based on this, this model was simplified from a 3-dimensional one to 2-dimensional one. Improvement of the difference method and coordinate system was proposed. Evolution of the 2-dimensional ice flow was simulated under coupled temperature field conditions. The results showed that the characteristic curves deriving from the conservation of the mass, momentum and energy agree with the results of ice sheet profile simulated with GLIMMER model and with the theoretical results. The application prospect of the simplified 2-dimensional ice flow model to simulate the relation of age-depth-accumulation in Dome A region was discussed.