Spaceborne Microwave Remote Sensing of Arctic Sea Ice During Spring

This paper outlines the fundamental roles sea ice plays during the spring Arctic climate, and it demonstrates the use of passive microwave remote sensing in measuring climatically important sea ice variables during the spring transitional period. It discusses the theoretical concepts underlying passive microwave remote sensing of sea ice, and it summarizes the historical use of satellite microwave radiometry in the Arctic region. In addition, this paper discusses the derivation of climatically important sea ice variables, including sea ice extent, concentration, multiyear ice fraction, and snow melt onset, with additional comments on the precision and accuracy of the remote sensing estimates. It also discusses interannual trends in sea ice extent and presents interannual trends in snow melt onset dates. Finally, this paper provides a brief discussion on the future directions in passive microwave remote sensing of climatically important sea ice variables during the spring transitional period.     

Spaceborne Microwave Remote Sensing of Arctic Sea Ice During Spring

This paper outlines the fundamental roles sea ice plays during the spring Arctic climate, and it demonstrates the use of passive microwave remote sensing in measuring climatically important sea ice variables during the spring transitional period. It discusses the theoretical concepts underlying passive microwave remote sensing of sea ice, and it summarizes the historical use of satellite microwave radiometry in the Arctic region. In addition, this paper discusses the derivation of climatically important sea ice variables, including sea ice extent, concentration, multiyear ice fraction, and snow melt onset, with additional comments on the precision and accuracy of the remote sensing estimates. It also discusses interannual trends in sea ice extent and presents interannual trends in snow melt onset dates. Finally, this paper provides a brief discussion on the future directions in passive microwave remote sensing of climatically important sea ice variables during the spring transitional period.     

Impact of the El Nino on the Variability of the Antarctic Sea Ice Extent

In this paper, the spreading way in the southern hemisphere that anomalous warm water piled in tropical eastern Pacific is analysed and then impact of El Nino on the variability of the Antarctic sea ice extent is investigated by using a dataset from 1970 to 2002. The analysis result show that in El Nino event the anomalous warm water piled in tropical eastern Pacific is poleward propagation yet the westward propagation along southern equator current hasn't been discovered . The poleward propagation time of the anomalous warm water is about 1 year or so. El Nino event has a close relationship with the sea ice extent in the Amundsen sea , Bellingshausen sea and Antarctic peninsula .After El Nino appears , there is a lag of two years that the sea ice in the Amundsen sea , Bellingshausea sea, especially in the Antarctic peninsula decreases obviously. The processes that El Nino has influence with Antarctic sea ice extent is the warm water piled in tropical eastern Pacific poleward propagation along off the coast of southern America and cause the anomalous temperature raise in near pole and then lead the sea ice in Amundsen sea , Bellingshausen sea and Antarctic peninsula to decrease where the obvious decrease of the sea ice since 80' decade has close relation to the frequently appearance of El Nino .     

北极迅速变暖条件下西北航道的海冰分布变化特征

北极近年迅速变暖使西北航道的通航成为可能。本文利用AMSR-E的6.25km分辨率日平均海冰密集度卫星数据研究了2002-2008年北极西北航道的海冰密集度变化特征。通过统计分析沿西北航线冰障关键流段代表站点的融化期、轻冰期、无冰期、无冰天数和轻冰天数,以及海冰分布和变化的某些细节,加深了对西北航道海冰季节变化和年际变化以及空间分布的主要特征,特别是与通航相关的冰情信息的了解。研究指出西北航道南路比北路容易开通;各线路冰障流段存在的时间呈减小趋势,整条线路无冰/轻冰天数呈增加趋势;冰间湖和冰间水道的产生和发展在很大程度上可能会影响到整个航路的融冰开始时间。     

Former extension of the East Antarctic Ice Sheet

Knowledge about the Quarternary geology of the Australian sector of Antarctica is very incomplete. Scattered observations of glacial deposits in that area, made during the ANARE 6 expedition in 1987, indicate that the inland ice had formerly a considerably wider extension than today. The ice was more than 200 m thicker, probably of the order 1, 000m. This maximum stage cannot yet be dated, but conditions seem to favour a late Wisconsin-Weichselian maximum age. However, a much higher age cannot be excluded.     

中国北极航线港口界定

随着北冰洋夏季冰层的逐渐消融,北极航线有望全线通航。北极航线的通航将促进东亚与欧洲、北美地区的贸易往来,从而降低传统航线的地位及作用,为我国战略资源采购提供新的通道;同时也将在一定程度上改变北极航线沿线及其延长线上港口的地位及布局,但不同港口受此影响不尽相同,只有部分港口可能因为北极航线的利用实现地位提升。在假定北极航线全线开通的基础上提出北极航线港口概念,以港口所在城市的进出口贸易总额为基本界定指标,以航程缩短程度、航线密度、港口外贸箱吞吐量和港口油气吞吐能力作为竞争性界定指标进行综合评价,筛选出符合标准的中国北极航线港口,为中国利用北极航线和未来沿海港口布局提供借鉴及参考。     

南北极海冰变化及其影响因素的对比分析

海冰是海洋-大气交互系统的重要组成部分,与全球气候系统间存在灵敏的响应和反馈机制。本文选用欧洲空间局发布的1992—2008年海冰密集度数据分析了南北极海冰在时间和空间上的变化规律与趋势,并结合由美国环境预报中心(National Centers for Environmental Prediction,NCEP)和美国大气研究中心(National Center for Atmospheric Research, NCAR)联合制作的NCEP/NCAR气温数据和ENSO指数探讨了南北极海冰变化的影响因素。结果表明,北极海冰面积呈明显的减少趋势,其中夏季海冰最小月的减少更快。北冰洋中央海盆区、巴伦支海、喀拉海、巴芬湾和拉布拉多海的减少最明显。南极海冰面积呈微弱增加趋势,罗斯海、太平洋扇区和大西洋扇区的海冰增加。北极海冰面积与气温有显著的滞后1个月的负相关关系(P0.01)。北极升温显著,北冰洋中央海盆区、喀拉海、巴伦支海、巴芬湾和楚科奇海升温趋势最大,海冰减少很明显。南极在南大西洋、南太平洋呈降温趋势,海冰增加。北极海冰减少与39个月之后ONI的下降、40个月之后SOI的上升密切相关;南极海冰增加与7个月之后ONI的下降、6个月之后SOI的上升存在很好的响应关系。南北极海冰变化与三次ENSO的强暖与强冷事件有很好的对应关系。     

南极冰盖表面微地貌研究进展与展望

南极冰盖表面微地貌是大气与冰盖相互作用的直接产物,微地貌的形态特征、结构性质及其发展变化对南极冰盖表面的物质平衡、能量平衡以及冰盖记录大气信息的过程具有重要的影响,冰盖表面微地貌的结构性质以及空间分布的确定是计算南极冰盖物质平衡与能量平衡的重要依据,同时在南极冰芯钻探选址以及冰芯解译古气候信息时具有重要的参考价值。根据微地貌的形成方式将南极冰盖表面微地貌分为沉积型、侵蚀型、沉积间断型三类,介绍了南极冰盖表面常见的微地貌形态雪丘、雪纹、雪垄、雪窝以及光洁区的形态特征与结构性质,并对冰盖表面微地貌的分布规律特征进行了总结,文中重点对不同微地貌区域内的物质平衡与能量平衡特征进行了介绍,最后探讨了冰盖表面光洁区对南极冰芯选址的影响,并对未来南极微地貌研究进行了展望。     

极涡面积指数与北太平洋海温季节变异相关分析

利用1951-2002年NCEP/NCAR的位势高度再分析资料,中国国家气候中心极涡面积指数和海温资料,研究极涡面积指数与北太平洋海温季节变异相关.结果表明,4个季节的太平洋极涡面积指数均与北太平洋的西风漂流区呈显著的负相关(显著性水平α≥0.05);冬季和春季太平洋极涡面积指数与同期太平洋海温呈相关显著的西北-东南向的"-、 "波列,为太平洋年代际振荡模态(PDO)分布;夏季和秋季北太平洋西风漂流区海温异常对滞后的冬季太平洋极涡面积指数变化影响显著;而春季的太平洋极涡面积指数变化对滞后的夏季和秋季西风漂流区海温变化影响显著;定义了风暴轴指数和西风漂流指数.春季太平洋极涡面积指数、北太平洋风暴轴和西风漂流区海温都在1969年发生突变,太平洋极涡面积明显增大,春季风暴轴亦相应偏南,西风漂流 ,区春季海温降低.     

基于Radarsat-2 SAR图像分类与HY-2微波辐射计反演获取北极海冰密集度的比较研究

在北极东北航道东西伯利亚海和楚科奇海交汇的关键区域,利用四景2012年北极夏季Radarsat-2 SAR海冰图像,通过图像分类提取了海冰密集度;同时采用NASA TEAM算法,基于海洋二号(HY-2)卫星扫描微波辐射计亮温数据反演了对应区域的海冰密集度;并引入美国冰雪数据中心(NSIDC)发布的SSMIS海冰密集度产品进行了对比研究。通过不同来源海冰密集度数据的分析发现HY-2、SAR和SSMIS的结果在4个研究区域上的分布趋势基本吻合;但在海冰边缘区,由SAR图像分类得到的海冰密集度高于HY-2和SSMIS的反演结果,说明了高分辨率的SAR图像在监测边缘区小尺寸浮冰上有优势。三种数据中,原始分辨率相同(25 km)的HY-2与SSMIS的结果最为相近,而HY-2同SAR的相关性与SAR同SSMIS的相关性一致。在冰边缘,HY-2的反演值偏低于SAR和SSMIS的结果,这是受该处较高水汽含量影响的结果,也是未来发展HY-2微波辐射计反演算法需要重点改进的地方。     

Development on management and sharing of data collected in Chinese Antarctic and Arctic Research Expeditions

Combined with the current status of Antarctic data management and the characteristics of polar science data resulted from Chinese Antarctic and Arctic Research Expeditions, the Chinese Polar Science Database System(CPSDS) has been designed and established in 2002. The infrastructure, technical standard, mechanism of sharing data of this system are reviewed in this article. Meanwhile, the development of Chinese polar data management is summarized. As the metadata is the powerful and useful tool for managing and disseminating scientific data, the metadata is also used as “search engine” of CPSDS. Besides, the trend of data management and sharing is also discussed.     

1979—2013年南大洋海冰变化特征及与典型气候变化因子的相关性分析

全球气候变化导致的南大洋海冰变化已引起广泛关注,基于近35年来该区域海冰覆盖范围的时空变化规律,运用Pearson相关和聚类分析等方法,探讨多元厄尔尼诺指数（MEI）、海洋尼诺指数（ONI）以及臭氧空洞面积气候变化因素与海冰覆盖范围的关系。南大洋海冰呈1.1%（±0.6%）小幅度增长,近5年印度洋海域海冰增长最快。1—6月别林斯高晋/阿蒙森海域、6—9月和11月威德尔海域海冰的多年变化趋势均为负增长。在南大洋5大片区中海冰与气候变化因子的关系不同,其中ONI影响别林斯高晋/阿蒙森、威德尔、印度洋、罗斯海海域;MEI主要影响印度洋和罗斯海海域;臭氧空洞主要影响罗斯海和威德尔海域。海冰变化对气候变化的响应存在不同程度的滞后性。     

基于灰度共生矩阵的Grove山地区冰裂隙探测

冰裂隙是内陆冰盖野外考察最危险因素之一。冰裂隙的识别保证了野外科学考察安全路线的选择,同时为研究冰体的运动提供了参考信息。本文基于SPOT5光学影像,利用灰度共生矩阵对东南极Grove山地区冰裂隙进行初步识别,并结合野外考察导航路线对结果进行分析,为野外考察提供参考。     

近500 年南极涛动指数重建及其变率分析

南极涛动是南半球大气环流的主要模态, 在多种尺度上对南半球及北半球部分地区的气候系统产生重要影响。在对树轮、珊瑚、冰芯等多种代用资料进行挑选与主成分分析的基础上,重建了公元1500 年以来南半球夏季(当年12 月-次年2 月) 的南极涛动指数。重建序列的解释方差(r2)、误差减少量(RE) 平均值分别为59.9%、0.47,较高的r2、RE表明重建具有了较高的可信度;而整体呈减少趋势的标准误差(SE) 表明代用资料的增多可以减少重建序列的不确定性。重建结果与其它研究给出的南极涛动指数有着较好的一致性。重建序列的功率谱分析表明,过去500 多年南极涛动年际变率突出的周期有2.4a、2.6a、6.3a,年代际变率突出的周期有24.1a、37.6a,均达到95%显著性水平。进一步的小波分析表明南极涛动在不同时间尺度上的变率及其周期有着随时间而演变的特征。     

A hindcast simulation of Arctic and Antarctic sea ice variability, 1955–2001

A hindcast simulation of the Arctic and Antarctic sea ice variability during 1955-2001 has been performed with a global, coarse resolution ice-ocean model driven by the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis daily surface air temperatures and winds. Both the mean state and variability of the ice packs over the satellite observing period are reasonably well reproduced by the model. Over the 47-year period, the simulated ice area (defined as the total ice-covered oceanic area) in each hemisphere experiences large decadal variability together with a decreasing trend of Ø1% per decade. In the Southern Hemisphere, this trend is mostly caused by an abrupt retreat of the ice cover during the second half of the 1970s and the beginning of the 1980s. The modelled ice volume also exhibits pronounced decadal variability, especially in the Northern Hemisphere. Besides these fluctuations, we detected a downward trend in Arctic ice volume of 1.8% per decade and an upward trend in Antarctic ice volume of 1.5% per decade. However, caution must be exercised when interpreting these trends because of the shortness of the simulation and the strong decadal variations. Furthermore, sensitivity experiments have revealed that the trend in Antarctic ice volume is model-dependent.     

极地海冰厚度探测方法及其应用研究综述

海冰是全球气候变化的敏感指示器,对全球热平衡、大气环流、海洋水循环和温盐平衡起到至关重要的作用。海冰厚度作为海冰中最重要的参数之一,也是最难探测的地球物理参数。在回顾和分析基于仰视声纳、走航观测、电磁感应、微波遥感等方法进行极地海冰厚度探测和应用研究的基础上,着重阐述近年来利用卫星测高技术估算极地海冰厚度的研究现状与趋势,为我国开展相关科研工作提供参考。     

Limnology of Two Antarctic Epishelf Lakes and their Potential to Record Periods of Ice Shelf Loss

George VI Ice Shelf is the largest ice shelf on the western side of the Antarctic Peninsula and its northern margin marks the southern most latitudinal limit of recent ice shelf retreat. As part of a project to reconstruct the long-term (Holocene) history of George VI Ice Shelf we studied two epishelf lakes impounded by the ice shelf at Ablation Point, on the east coast of Alexander Island. These lakes, Moutonnée and Ablation, are stratified water bodies with a lower marine layer and an upper freshwater layer. To determine if their sediment records could be used to detect past changes in the presence or absence of the ice shelf it was necessary to describe their present-day limnology and sedimentology. We measured water column chemistry and sampled the water column and sediments of the lakes along vertical and horizontal transects. We analysed these samples for diatoms, stable isotopes (δ¹⁸O, δ²H, δ¹³C_DIC, δ¹³C_org), geochemistry (TOC, TN, C/N ratios) and physical sedimentology (grain-size). This was supplemented by chemical and biological reference data from the catchments. Results showed that the water columns of both lakes are nutrient limited and deficient in phytoplankton. Benthic productivity is low and decreases with depth. Comparison of water column chemistry with an earlier survey shows a net increase in the thickness of the freshwater layer in Moutonnée Lake between 1973 and 2001, which could indicate that George VI Ice Shelf has thinned during this period. However, a similar trend was not observed in Ablation Lake (5 km to the north) and an alternative explanation is that the changes are a seasonal phenomena. Data from the surface sediment transects identified a number of proxies that respond to the present day stratification of the water column including diatom species composition, stable isotopes and geochemistry, particularly in Moutonnée Lake. Collectively these data have been used to develop a conceptual model for determining past ice shelf configuration in epishelf lakes. Specifically, periods of past ice shelf loss, and the removal of the ice dam, would see the present stratified epishelf lake replaced by a marine embayment. It is suggested that this change would leave a clear signature in the lake sediment record, notably the deposition of an exclusively marine biological assemblage, increased ice rafted debris and δ¹³C_org values that are indicative of marine derived organic matter. These authors contributed equally to this work     

基于Elmer/Ice冰盖模型的南极Gamburtsev山脉Lambert冰川冰盖系统的数值模式模拟研究

在全球变暖的背景下, 东南极冰盖显著地出现降雪增多冰厚增大的现象, 然而由于有关东南极冰盖 的观测数据相对缺乏, 因而很难对东南极冰盖大范围的冰盖动力学、热力学状态细节进行整体性评估。 Dome A 到中山站断面是横穿南极冰盖计划的核心断面之一。该断面穿越的兰伯特(Lambert)冰川上游、甘 布尔采夫(Gamburtsev)冰下山脉和Dome A 区域是南极科学研究的热点区域, 因此具有重要的研究价值。本 研究使用已多次在南极冰盖有过成功模拟应用的三维有限元冰盖模式Elmer/Ice, 对该区域的内部温度场和 速度场进行了模拟, 得到了冰盖的流速场和温度场数据, 并将模拟数据与传统估测数据进行了对比, 发现 两者在总体趋势上吻合。研究表明, 该研究区域冰盖的底部温度大部分达到了压力熔点, 只有少部分靠近内 陆的冰盖底部未达到; 在冰盖内陆区域, 水平速度场非常小, 在靠近冰架区域时, 水平速度场突然增大, 而 垂直速度场只有在冰下地形发生显著波动时, 出现显著变化。在此基础上, 对Elmer/Ice 冰盖模式的应用前 景和需改进的方面进行了探讨。