Climatic trend and the retreat and disintegration of ice shelves on the Antarctic Peninsula: an overview

Observation of the retreat and disintegration of ice shelves around the Antarctic Peninsula during the last three decades and associated changes in air temperature, measured at various meteorological stations on the Antarctic Peninsula, are reviewed. The climatically induced retreat of the northern Larsen Ice Shelf on the east coast and of the Wordie, George VI, and Wilkins ice shelves on the west coast amounted to about 10 000 km² since the mid-1960s. A summary is presented on the recession history of the Larsen Ice Shelf and on the collapse of those sections north of Robertson Island in early 1995. The area changes were derived from images of various satellites, dating back to a late 1963 image from the recently declassified US Argon space missions. This photograph reveals a previously unknown, minor advance of the northern Larsen Ice Shelf before 1975. During the period of retreat a consistent and pronounced warming trend was observed at the stations on both east and west coasts of the Antarctic Peninsula, but a major cause of the fast retreat and final collapse of the northernmost sections of the Larsen Ice Shelf were several unusually warm summers. Temperature records from the nearby station Marambio show that a positive mean summer temperature was reached for the first time in 1992-93. Recent observations indicate that the process of ice shelf disintegration is proceeding further south on both sides of the Antarctic Peninsula.     

南极潮汐测量及区域潮汐对冰架表面流速影响的研究进展综述

南极区域潮汐是计算南极物质平衡和南极冰架表面冰流速的重要影响因素,同时对于研究冰架崩解和全球气候变暖具有重要作用。南极潮汐测量的方法从最初的实时测量,发展到了卫星测高和遥感监测以及建立数值模型预测的阶段。已有研究表明潮汐周期与冰架表面流速间存在一定关联,例如Filchner-Ronne冰架和Ross冰架的潮汐变化与冰流速度的联系为:在大潮时冰流速度达到最快,小潮时冰流速度达到最慢。研究还对南极典型冰架区域潮汐特征及对冰架表面冰流速、高程变化等的影响进行了总结。今后的研究不仅需要继续关注西南极和南极半岛的潮汐变化,更加需要对东南极稀疏的区域进行潮汐观测,这对于构建整个南极潮汐数据库和提高数值模型的精度具有重要意义。     

Glacial history of the Antarctic Peninsula since the Last Glacial Maximum–a synthesis

The extent of ice, thickness and dynamics of the Last Glacial Maximum (LGM) ice sheets in the Antarctic Peninsula region, as well as the pattern of subsequent deglaciation and climate development, are not well constrained in time and space. During the LGM, ice thickened considerably and expanded towards the middle–outer submarine shelves around the Antarctic Peninsula. Deglaciation was slow, occurring mainly between >14 Ky BP (¹⁴C kilo years before present) and ca. 6 Ky BP, when interglacial climate was established in the region. After a climate optimum, peaking ca. 4 - 3 Ky BP, a cooling trend started, with expanding glaciers and ice shelves. Rapid warming during the past 50 years may be causing instability to some Antarctic Peninsula ice shelves.     

南极冰架-海洋相互作用研究综述

本文介绍了近期南极冰架-海洋相互作用的研究进展。冰架底部融化速率大于前缘崩解通量,成为南极冰盖质量损失的首要途径。冰架下的海洋按照底部融化驱动因素的不同,可以分为由高密度陆架水驱动的冷冰腔和由变性绕极深层水驱动的暖冰腔。威德尔海的菲尔希纳-龙尼冰架和罗斯海的罗斯冰架属于冷冰腔,占南极冰架总面积的2/3,却只贡献了15%的净融化;东南太平洋扇区阿蒙森海和别林斯高晋海等若干属于暖冰腔的小型冰架,虽然只占南极冰架总面积的8%,却贡献了超过一半的冰架融水。以往看做冷冰腔的东南极托滕冰架和埃默里冰架,也相继发现有变性绕极深层水进入冰腔并造成底部融化。冰架对海洋有冷却和淡化的作用。冷冰腔输出的冰架水具有海洋中最低的温度,对南极陆架水性质乃至南极底层水的形成都有影响。冰架融化加剧,可能是近期观测到的南极底层水淡化的原因。     

南极冰架研究现状与埃默里冰架研究展望

南极冰架是揭示南极地区气候变化机制,预测全球气候变化的关键研究区域之一。概述了20世纪以来针对南极冰架所开展的科学研究工作,分别从冰架物质平衡过程、冰架形态特征及其内部结构监测、冰架海底海洋岩芯的沉积特征和冰架附近海域生态系统演化等方面总结了冰架研究所取得的丰硕成果。介绍了中国近几年在东南极洲埃默里冰架进行的科学考察活动,并依据南极冰架研究的国际未来计划提出了中国在埃默里冰架即将继续开展的研究工作。     

南极洲维斯特福尔德丘陵与菲尔德斯半岛冰缘地貌的比较研究

东南极大陆沿岸的维斯特福尔德丘陵(68°22'～68°40'S,77°55'～78°30'E)和西南极乔治王岛南端的菲尔德斯半岛(62°08'～62°20'S,58°45'～58°58'W)的气候条件不同。前者属于极地大陆性气候,气温低,冬季严寒,干燥、风大,夏季较短;后者属于极地海洋性气候,气温不很低,湿润、风小,夏季较长。因此,两地的冰缘地貌的组合类型及其发育过程存在明显的差异。前者冰缘地貌单一,发展速度较慢;后者冰缘地貌复杂多样,发展速度较快。 本文根据实地观测资料,对极地大陆型和极地海洋型两类冰缘地貌作一些比较,并且提出,年冻融日数是决定冰缘作用强弱的最重要指标。     

南极冰盖的物质平衡研究:进展与展望

南极冰盖物质平衡最新的研究进展表明,西南极洲表现出两种变化模式,西部在增厚,而北面在更快地减薄。西南极冰盖总体可能正在减薄,其物质损失的速率可能足以使海平面每年上升近0.2mm。东南极冰盖物质不平衡可能很小,甚至其符号还不能被确定。南极半岛正在经历着快速变化。目前还不能可靠地估算南极冰盖的物质平衡状态。同时,大型冰川的停滞,一些冰川流速加快,冰盖大范围加速减薄,冰架大面积的快速崩解和支流冰川的加速,以及着地线强烈的底部融化等显示出南极冰盖存在快速变化。南极冰盖物质平衡未来的重点研究领域是开展冰盖表面高程变化的监测与模拟,确定表面物质平衡及其在各冰流盆地的分布,着地线的冰流通量,冰架底部的融化,了解冰后期冰盖退缩的动力过程,以及开发、对比和改进与冰盖物质平衡模拟和预测相关的各种模型。     

Interdecadal oscillations of temperatures in 1903-2002 over the Antarctic Peninula

<正> In the paper,by use of the monthly mean temperature data of 12 sta-tions in the vicinity of Antarctic Peninsula,the temperature series during 1903-2000 is founded and the interdecadal oscillation of the temperature are discussed.The results indicate that 1) There are three jumps during 1919-1923,1947-1953 and 1976-1982 in recent hundred years and the stable climate step betweentwo jump points lasted about 30 years.2)Annual mean temperature is increasedby 0.730℃ in an echelon during 1903-2000,the warming extent is dissimilarityin each season,the maximum of warming is in the winter and the minimum ofwarming is in summer.3)The ice decline trend is presented in the index of Iceconcentration in the vicinity sea of Antarctic Peninsula,which shows a-0.2053/10a drop,and the decrease trend of the ice concentration index in summerhalf year(Dec-May)is found much more obviously than that in winter half year(Jun-Nov).4)There is better negative relationship between the temperature andthe Ice concentration index in Antarctic Peninsula and its vicinity sea,which cor-relation coefficient of is exceed the significance level of 5% in summer,autumnand annual. Antarctic Peninsula,temperature,sea ice,oscillation.     

南极海冰、冰穴和冰川冰及其对水团形成和变性的作用

本文利用前人的成果及笔者1992/1993年的南极海冰观测和收集的资料以及水文观测资料数据阐述了南极海冰的特性,特别是南极海冰过程、冰穴以及冰川冰对南极水团(南极表层水、南极底层水、南极陆架水、南极中层水以及南极冰架水)的形成和变性所起的特殊作用。 南极海冰覆盖面积的年际变化,夏季最大年份是最小年份的2倍多,冬季年间变化较小,最大仅为20％;但其季节变化非常大,冬季平均覆盖面积通常是夏季的5倍。南极海冰对大气-海洋间相互作用有重大影响,特别是深海洋区中冬季的结冰和发育造成的垂向对流、夏季的融化是形成南极表层水(含南极冬季水和南极夏季表层水),进而形成南极中层水的主要原因;南极陆架区的的海冰兴衰过程是形成南极陆架水的直接原因,它与变性南极绕极深层水混合并受到冰川冰的进一步冷却作用,成为形成南极底层水的主要水团;南极冰架底部的冷却、融化和冰架以下水体的结冰作用形成的高盐对流过程产生的南极冰架水,亦是形成南极底层水的贡献者。 冰穴是70年代以来卫星观测的重大发现。对其形成和对大气、海洋的影响作用尚不完全清楚,初步的研究成果表明,冰穴中产生的热盐对流对南极水团的形成、变性、大洋深层的翻转以及海洋-大气间的热量传输和气体交换起有非常重要的作用。     

Spatial Sciences on Ice: 50 years of Australian activities on the Amery Ice Shelf,East Antarctica

The Antarctic climate system involves many complex interactions between the atmosphere, oceans and ice and is sensitive to variations in these components. Ice shelves represent the ice–ocean–atmosphere interface of the Antarctic continent and are therefore very important indicators of climate change in the region. The Amery Ice Shelf is the largest ice shelf in East Antarctica and has been the focus of many scientific research projects over the past 50 years. This paper presents a history of the use of spatial science techniques from basic survey equipment to satellite systems in Australian research projects based on the Amery Ice Shelf (and surrounding glaciers) since 1955. The application of these spatial data to projects based primarily in the fields of geodesy, glaciology, climatology, and oceanography has allowed the measurement and monitoring of the physical, dynamic and environmental characteristics of this large and remote region. This new information provides scientists with a better understanding of the ice shelf/ocean/atmosphere system allowing future monitoring to observe the effects of global climate change.     

The tidal signals extraction from GPS data on the Amery Ice Shelf, Antarctica

Tidal motion is the source of short-term vertical motion that an ice shelf experiences, and hence has a significant impact on ice shelves. During the 2003/2004 Austral summer season, five days of GPS measurements were carried out on the front of the Amery Ice Shelf （AIS）, East Antarctica, by the 20th Chinese National Antarctica Research Expedition （CHINARE）. The GPS data was processed using GAMIT/GLOBK software with 2-hour static data segment and the vertical precision is less than 0.18 m. To verify our results for the vertical component, we compare the ice shelf GPS tidal signal with a tidal result derived from tide gauge measurements at China＇s Zhongshan Station on Antarctica. Comparison of the GPS results with the tide gauge were in good agreement in amplitude at the few cm level, which indicates that the tide under the front of Amery Ice Shelf is irregular semidiurnal tide, the maximal tidal differences is approximately 2 m. GPS data can be used to validate the ocean tide model around the Antarctic area and such studies are important to improve our knowledge of the Antarctic ice shelf mass balance and dynamical models of ice sheet/ocean interaction.     

Remote monitoriug ice velocities of the polar record and the Dark Glaciers

Measurement of ice velocities of the Antarctic glaciers is very important for studies on Antarctic ice and snow mass balance. The polar area environmental change and its influences on the global environment. Conventional methods may be used for measuring the ice velocities, but they suffer from severe weather conditions in the Polar areas. Use of satellite multi-spectral and muki-temporal images makes it easier to measure the velocities of the glacier movements. This paper discusses a new method for monitoring the glacial change by means of multi-temporal satellite images. Temporal remotely sensed images in the Ingrid Christensen coast were processed with respect to geometric rectification, registration and overlay, The average ice velocities of the Polar Record Glacier and the Dark Glacier were then calculated, with the changing characteristics analyzed and evaluated. The advantages of the method reported here include promise of all-weather operation and potentials of dynamic monitoring through suitabl     

THE ENVIRONMENTAL EVENTS ON KING GEORGE ISLAND SINCE THE LAST GLACIATION

The extension of ice sheet on King George Island during the last glaciation was an environment event since the last glaciation. At that time South Shedlands Islands were a large unified island and the ice mass on King George Island might come from the Antarctic Peninsula. The model of ice retreat and ice advance events in the Holocene show that the ice sheet was separated into three small ice caps and then dispeared gradually. At present the retreating velocity of glacier is about 1.3m each year. After the retreat of ice sheet the isostatic compensation appeared in the crust there, and then 5-6 steps of the uplifted marine terraces have been developed along the coast. The uplift rate of the crust may be 6-10mm/a.     

Physical oceanography studies in the Weddell Sea during the Norwegian Antarctic Research Expedition 1978/79

Hydrographic and current measurements obtained during the Norwegian Antarctic Research Expedition 1978/79 to the southern Weddell Sea are presented. Cold, dense Ice Shelf Water circulating under the floating ice shelves is observed to leave the shelf as a concentrated bottom flow. From moored current metres this discharge is estimated at 0.7 10⁶ m³/s at -2.0°C (one year average) and with no appreciable seasonal variation. This contribution to the Weddell Sea Bottom Water is clearly identified through extreme temperature gradients at our deepest stations (below 2500 m). The core of Weddell Deep Water shows a considerable (T ∼ 0.5°C) warming up since 1977, presumably due to the lack of polynya activity in the intervening period. Measurements in the coastal current at the ice shelf (70°S, 2°W) show step structures which are probably due to cooling and melting at the vertical ice barrier. Slight supercooling due to circulation under the ice shelf is also seen. The net effect of the ice shelf boundary seems to be a deep reaching cooling and freshening of the coastal current providing the low salinity, freezing point Eastern Shelf Water. This process is considered a preconditioning which enhances production of the saline Western Shelf Water which in turn is transformed to Ice Shelf Water.     

南极冰盖表面冰流速研究综述

冰川表面流速作为南极冰盖物质平衡估算的一项重要内容,对于研究全球变暖背景下的海平面上升具有重要意义。随着技术的进步,南极的冰流速监测方法已经从传统的花杆测量、光学仪器边角测量,发展到先进的GPS测量和遥感观测。南极冰盖冰流速总体特征是:海岸带冰流速快于内陆冰流速,冰架冰流速快于陆地冰流速,西南极冰流速快于东南极冰流速。未来加强对数据稀疏地区的冰流速监测,扩大冰流速研究的时间尺度,开发冰流速研究的新方法以及构建冰流速波动与气候变化相互关系模型等,成为南极冰流速研究的新热点。     

极地记录冰川和达尔克冰川流速的遥感监测研究

测定南极冰川的流速 ,对于研究南极冰雪物质平衡、南极环境变化及其对全球环境的影响有重大意义。本文论述了利用多时相卫星遥感影像监测冰川变化的原理和方法 ,通过对英格里特 .克里斯泰森海岸不同时期的遥感影像进行几何纠正和配准及叠加处理 ,测量和计算出极地记录冰川和达尔克冰川的平均流速 ,并对它们的变化特点进行了初步的分析和评价。     

PISM冰盖模式对Amery冰架流速场模拟的适用性

在全球气候变暖的背景下,冰架系统是监视和预测冰盖稳定性的理想研究区域。然而传统的冰架观测与调查方法只能从某一侧面揭示冰架的运动状态和演化信息,无法预测其未来变化;冰盖模式作为非常有潜力的数值计算方法,成为研究和预测冰盖/冰架演化的热点领域。Lambert冰川-Amery冰架系统是东南极冰盖最大的冰川系统,对于研究东南极冰盖的物质平衡和冰盖稳定性具有重要意义。使用PISM冰盖模式,对该冰川系统的流动过程进行模拟,得到冰表面流速场数据,并将模拟流速场与实测数据进行对比,发现两者在大部分区域吻合较好,但在冰架前缘处呈现出一些差异。进一步讨论差异可能的来源以及模拟可以改进的地方。     

Mountain-derived versus shelf-based glaciations on the western Taymyr Peninsula, Siberia

The early Russian researchers working in central Siberia seem to have preferred scenarios in which glaciations, in accordance with the classical glaciological concept, originated in the mountains. However, during the last 30 years or so the interest in the glacial history of the region has concentrated on ice sheets spreading from the Kara Sea shelf. There, they could have originated from ice caps formed on areas that, for eustatic reasons, became dry land during global glacial maximum periods, or from grounded ice shelves. Such ice sheets have been shown to repeatedly inundate much of the Taymyr Peninsula from the north-west. However, work on westernmost Taymyr has now also documented glaciations coming from inland. On at least two occasions, with the latest one dated to the Saale glaciation (marine isotope stage 6 [MIS 6]), warm-based, bedrock-sculpturing glaciers originating in the Byrranga Mountains, and in the hills west of the range, expanded westwards, and at least once did such glaciers, after moving 50–60 km or more over the present land areas, cross today's Kara Sea coastline. The last major glaciation affecting south-western Taymyr did, however, come from the Kara Sea shelf. According to optically stimulated luminescence dates, this was during the Early or Middle Weichselian (MIS 5 or 4), and was most probably not later than 70 Kya. South-western Taymyr was not extensively glaciated during the last global glacial maximum ca. 20 Kya, although local cold-based ice caps may have existed.     

基于特征跟踪方法的Amery冰架上游流速估算

冰川流速分析对于研究南极冰盖物质平衡、海平面上升和全球气候变化具有重要意义。以ALOS/PALSAR影像为数据源,采用SAR特征跟踪方法,结合DEM数据估算Amery冰架上游冰川流速。结果表明,Amery冰架上游主流线流速为540—720 m·a-1,冰川流速随海拔的降低逐渐减小。受基岩和两侧山体的影响,主流线流速大,越靠近两侧山体流速越小。这个结果与NASA 2000年利用SAR重复轨道干涉测量方法测定的流速接近。基于裸露岩石作为特征点的分析表明,该方法误差较小,获取的冰川流速比较可靠。     

用GPS技术监测南极半岛地区形变的结果初步分析

“全南极 GPS国际联测”已经进行了 6期观测。我们选取了位于西南极乔治王岛地区的 7个 GPS站 ,并加入 2个 IGS站 ,分别对 1 995、1 996、1 998年的同期 (GPS年积日 0 2 0 - 0 4 0 )观测数据进行了基线处理 ,相对精度可达 1 0 - 8- 1 0 - 9。并对 GAMIT软件解算得到的松弛解和强约束解分别进行了网平差处理 ,结果证明该地区比较稳定 ,总体上有 1 0 mm/a左右向西南方向的运动趋势。