乌梁素海湖泊冰生长过程中总氮的迁移规律

为研究湖泊冰封期总氮的污染特征,测定了冰厚分别为0 cm、2.5 cm、9.5 cm、21 cm、31 cm、41 cm、50 cm和 59 cm时总氮在冰体和水体中的垂向分布,阐明湖泊冰生长过程中总氮在冰-水-沉积物体系的迁移规律。结果表明:冰生长过程中总氮由冰体向冰下水体迁移,水体的总氮含量随着冰厚的增加而升高,冰厚为59 cm时其含量为冰体的2.85倍,冰生长速率决定总氮在冰-水界面处的迁移通量;总氮在冰层内的迁移主要发生在冰体形成初期(0~21 cm),之后几乎不再迁移而与冰内气泡融合并转化为独立于冰体的稳定氮胞;冰下水体总氮的实测值小于其计算值,表明冰生长过程中总氮由水体向沉积物迁移。     

新疆阿尔泰山喀纳斯湖冰层温度变化规律试验研究

2014年12月-2015年4月期间,新疆布尔津县喀纳斯湖举行了冰上旅游项目。为监测冰层生长、发育和融化状况,分别对喀纳斯湖（湖边、湖中）A、B、C三点进行温度监测,利用监测得到的冰层温度数据绘制湖冰从上到下温度分布状况图。根据湖边与湖中的冰层结构特点,从冰层的天然结构角度分析湖冰结构对温度分布的影响。结果表明：天然冰层中温度传递系数并不是一致不变的,既受冰上气温、冰下湖水温度的影响,也受到冰层自身结构状况的影响,并进一步阐述了湖面冰层的温度分布规律与变化成因,为分析温度对冰层强度的影响奠定了基础。     

分子动力学模拟研究未冻水对冰晶体力学性质的影响

冰力学性质的研究在冻土工程、冰工程中都占据极其重要的地位,冰中未冻水含量的变化会导致冰整体性质随之改变。目前,在微观分子尺度上针对冰中未冻水含量控制因素方面的研究尚不充分。本研究通过分子动力学方法模拟了5种温度、3种应变速率、4种晶粒尺寸、3种升温速率下单晶冰与多晶冰的单轴拉伸与压缩试验,研究了不同影响因素下冰晶体力学性质及内部的微观结构变化,揭示了分子尺度上未冻水在冰晶体变形过程中的产生过程与变化规律,以及未冻水比例对冰晶体力学性质影响的内在机理。模拟结果显示,单晶冰力学性质与未冻水比例间的关系不显著,与冰晶体六元环结构的破损程度直接相关。此外,力学性质受温度、应变量、应变速率等多因素影响,且在拉伸和压缩过程中单晶冰均表现出明显脆性破坏,其强度随温度降低和应变速率加快而增强。相比之下,多晶冰力学性质与未冻水比例变化密切相关,且未冻水比例主要受温度、晶粒大小及其界面状态控制。而且,多晶冰对温度和应变速率更敏感,说明晶界处的结构变化对其力学性能起重要作用。与弹性变形不同,晶界滑移、晶粒旋转、非晶化和再结晶等过程主导多晶冰的塑性变形。     

季节性冰封热融浅湖水温原位观测及其分层特征

为探究季节性冰封浅湖热力学特征,于2010年10月至2013年7月对高原腹地一典型热融湖塘冰层生消、水/冰温及气象条件开展原位观测,分析了水温分布时间变化、温跃层以及冰生消对水温结构的影响。结果发现:冰面升华显著,贯穿整个冰期;水温日变化、季节变化和垂直结构受气温、大气辐射、风速、冰生消和湖底沉积层热贡献影响显著;在"无冰期-结冰前-冰生长期-冰融化期-融化后-无冰期"年循环过程中水温垂直结构分别呈现出"分层-翻转-逆温分层-逆温与正温共存-翻转-分层"的循环过程。分层期水温结构仅由上部混合层和温跃层构成,且偶因强风搅动而全湖翻转混合。可见,相比大中型湖泊,季节性冰封浅湖热力学结构差异显著。     

南极纳拉海峡固定冰生长、 结构、 盐度和氧同位素组成

采用第19次中国南极科考采集的冰芯样品、 数据, 基于海冰的"冻结日"记录, 使用海冰一维热力学模型来计算纳拉海峡固定冰的生长厚度. 考虑气象条件以及冰情观测结果, 将该模型的计算海冰厚度和实测厚度进行比较发现, 在纳拉海峡存在着多年生长的海冰. 对采集于南极洲中山站附近纳拉海峡的固定冰冰芯样品进行结构、 盐度和稳定氧同位素(δ~(18)O)分析, 获取了海冰的结构和盐度剖面特征、 冰芯雪冰、 附加冰的含量、 雪冰中的雪以及全部冰芯中雪所占的百分比. 结果表明: 样品冰芯具有典型的海冰特征结构, 如柱状冰水平方向的C轴以及上部粒状冰层和下部柱状冰层结构特征, 部分柱状冰中间存在着粒状冰夹层; 盐度和δ~(18)O剖面也显示了多年冰生长的证据. 海冰的结构和氧同位素特征表明, 纳拉海峡固定冰的生长主要受热力学过程控制, 其结果和2000年1月至2003年2月人工冰情观测结果一致, 观测中没有发现冰脊、 叠置等动力过程. 附加冰在冰芯中所占的比例平均为5.01%. 使用不同的同位素标准来区分雪冰层, 估计研究区域平均有多达16.4%～37.9%的雪冰, 海冰粒状层中雪的部分约占全部冰厚度的0.8%～23.5%.     

南极纳拉海峡固定冰生长、结构、盐度和氧同位素组成

采用第19次中国南极科考采集的冰芯样品、数据,基于海冰的"冻结日"记录,使用海冰一维热力学模型来计算纳拉海峡固定冰的生长厚度.考虑气象条件以及冰情观测结果,将该模型的计算海冰厚度和实测厚度进行比较发现,在纳拉海峡存在着多年生长的海冰.对采集于南极洲中山站附近纳拉海峡的固定冰冰芯样品进行结构、盐度和稳定氧同位素(δ18O)分析,获取了海冰的结构和盐度剖面特征、冰芯雪冰、附加冰的含量、雪冰中的雪以及全部冰芯中雪所占的百分比.结果表明:样品冰芯具有典型的海冰特征结构,如柱状冰水平方向的C轴以及上部粒状冰层和下部柱状冰层结构特征,部分柱状冰中间存在着粒状冰夹层;盐度和δ18O剖面也显示了多年冰生长的证据.海冰的结构和氧同位素特征表明,纳拉海峡固定冰的生长主要受热力学过程控制,其结果和2000年1月至2003年2月人工冰情观测结果一致,观测中没有发现冰脊、叠置等动力过程.附加冰在冰芯中所占的比例平均为5.01%.使用不同的同位素标准来区分雪冰层,估计研究区域平均有多达16.4%～37.9%的雪冰,海冰粒状层中雪的部分约占全部冰厚度的0.8%～23.5%.     

乌鲁木齐河源1号冰川积累区透底冰芯地层及冰结构分析

对乌鲁木齐河源１号冰川积累区一支深达９１．６４ｍ的透底冰芯进行了详细的层位及冰结构分析，结果表明，在２０ｍ深度以内，很好地保存了原始沉积的特征，但在７０￣８０ｍ深处还发现小密度的乳白色冰占优势的冰层，可能形成于小冰期，中层具有动力变质及再结晶作用共存及反复消长的结构特征（冰晶尺寸、气泡），未见单极大型组构，但出现弱竖环形组构，底层出现弱宝石状的多极大组构。     

利用被动微波探测青海湖湖冰物候变化特征

湖冰物候是气候变化的敏感因子,不仅能反映区域气候变化特征,还可以反映区域气候与湖泊相互作用。利用长时间序列（1978—2018年）被动微波遥感18 GHz和19 GHz亮度温度数据、MODIS数据（2000—2018年）、实测湖冰厚度数据（1983—2018年）和气温、风速、降水（雪）数据（1961—2018年）,分析青海湖湖冰变化特征及其对气候变化的响应。结果表明：青海湖流域呈现显著的变暖趋势（1961—2018年）,气温上升2.85 ℃,在这种气候条件下,青海湖湖冰封冻日推迟（0.23 d·a^-1）,消融日呈现明显的提前趋势（0.33 d·a^-1）,湖冰封冻期天数明显减少,减少速率为0.57 d·a^-1;同时,湖冰厚度以0.29 cm·a^-1的速率减薄。此外,总结归纳了青海湖冻结-融化空间特征,青海湖主要由东部海晏湾地区开始冻结,从西部黑马河等地区开始消融,冻结和消融过程存在空间差异。通过分析湖冰冻融特征和气候因子关系发现,青海湖流域冬季气温是影响青海湖湖冰物候变化的主要因素,同时风速和降水（雪）也是影响湖冰发育和消融的重要因素。     

达里诺尔湖水体稳定氢、氧同位素组成变化对结冰过程的响应

利用自然界中广泛分布的环境同位素进行湖泊水体演化过程分析已经成为现代湖泊科学的重要研究方向.通过采集内蒙古达里诺尔湖(简称"达里湖") 2013年1月份的湖冰、湖水, 2012年夏季湖水与湖区大气降水等, 共分析了77个样品中稳定氢(H)、氧(O)同位素值的变化情况, 在此基础上对达里湖水体稳定H、O同位素组成变化及其对结冰过程的响应进行了详细分析, 结果显示: (1)伴随结冰过程的完成, 各站点深层冰体(厚度~65 cm)中δD、δ18O值比表层冰体(厚度~15 cm)中的值出现不同幅度的偏重.而冰下水体中δD、δ18O平均值则比冰体中的平均值分别偏轻约13.85‰、2.23‰.在冰层形成的快速与稳定阶段, δD、δ18O值的变化幅度也存在差异.同时, 冬季外源水体的输入对各站点间同位素值差异的影响比夏季更明显; (2)夏季湖水、冬季湖水与湖冰的同位素值均落在全球大气降水线与湖区大气降水线之外, 显示湖泊冰封之前, 蒸发对湖泊水体同位素偏移存在一定程度的影响; 而冬季湖水与湖冰的同位素值基本位于同一斜率区间, 且全部落在夏季湖水同位素值的右侧, 显示两者之间并不存在明显的蒸发分馏作用, 造成上述现象的因素只能归结于结冰过程.      

冰层厚度传感器及其检测方法

水结冰和冰融化过程中的电阻、电容、温度物理参数与被检测冰表面以上的空气层或冰下水层的电阻、电容、温度有一定的差异,有些差异在数值上比较明显。基于这一特点,笔者提出了利用空气、冰与水的物理特性差异实现对冰层厚度及冰下水位接触式检测的新思路,对含有导电杂质的冰、冰-水混合物、水、空气的电阻、电容特性随温度的变化规律进行了初步分析,并得到冰的弱导电性质和冰与水的电容区间单调特性,据此提出了冰层厚度传感器结构及其冰厚检测原理,介绍了新型冰层厚度传感器在实践中的应用。     

Study of inter-annual variations in surface melting over Amery Ice Shelf,East Antarctica,using space-borne scatterometer data

The widespread retreat of glaciers can be considered as a response to the climate change. Being the largest retreating glacier–ice shelf system in East Antarctica, the Amery Ice Shelf–Lambert Glacier system plays an important role in contributing to sea level rise as well as the surrounding environment and climate. The present study is focused on the investigation of surface melting over the ice shelf using QuikSCAT Ku-band scatterometer data for more than 100 months covering the period from January 2000 to July 2009. The corresponding weather data of Davis Station was obtained from the website of Australian Antarctic Division. Very prominent dips in the backscatter observed in the month of January form a distinct signature caused by physical process of significant melting of the ice/snow surface. The steep increase again in February is attributed to the initiation of the freezing phenomenon. The derived melting index compared well with the passive microwave-based melting index derived by other researchers. A strong relationship was found between the scatterometer-derived melting index and the cumulative monthly mean air temperature. The highest melting was observed in the summer (January) of 2004, and thereafter gradual cooling appeared to take place in the subsequent years. The snow pack thickness, inferred from the backscatter variations, was found to be higher during winters (June) of 2004 and 2005, compared with other years.     

从第三极到北极： 湖冰研究进展

在全球气候变暖背景下, 第三极和北极地区的增温尤其明显, 冰冻圈对气候变化有着更为敏感的响应。湖冰作为冰冻圈的重要组成部分, 其变化不仅是气候的指示器, 同时也通过改变能量平衡、 大气环流、 辐射平衡等影响区域气候。通过对比不同观测手段及主要模型模拟方法在湖冰研究中的优缺点及适用性, 总结了第三极和北极湖冰变化的时空特征, 结果表明：第三极和北极地区湖冰均显示初冰日推迟、 消融日提前、 封冻期缩短的趋势; 第三极和北极地区湖冰厚度呈持续减少趋势; 未来湖冰的这些变化将更加显著。第三极和北极地区湖冰的变化主要受到气温的影响, 同时也受到风速、 湖泊理化性质的限制。在系统梳理第三极和北极地区湖冰变化的基础上, 总结了湖冰研究面临的问题和挑战, 为未来湖冰研究提供科学依据。     

What is the deepest part of the Vostok ice core telling us?

This review paper is mainly concerned with a geochemical investigation of the deepest part of the Vostok ice core between 3310 m, the depth at which the palaeoenvironmental record present in the ice above is lost, and the bottom of the core about 130 m above subglacial Lake Vostok. Two sections constitute this part of the core.The upper section (3310–3539 m depth) still consists of ice of meteoric origin but subjected to widespread complex deformation. This deformation is analysed in light of a δD–deuterium excess diagram and information on microparticles, crystal sizes and chemical elements distributions in that part of the core. Such ice deformation occurred when the ice was still grounded upstream from Vostok station in a region with subfreezing temperatures.The lower section from 3539 m to the bottom of the core at 3623 m depth is lake ice formed by freezing of subglacial Lake Vostok waters. This is indicated by the isotopic properties (δD, δ¹⁸O and deuterium excess), by electrical conductivity measurements (ECM), crystallography and gas content of the ice. These ice core data together with data on ionic chemistry favour an origin of the lake ice by frazil ice generation in a supercooled (below pressure melting point) water plume existing in the lake followed by accretion and consolidation by subsequent freezing of the host water.The helium profile of this deepest part of the Vostok core is quite unusual and surprising. It has important implications for the interactions between the ice sheet and the lake. Two constrasting scenarios can be satisfactorily constructed so that the lake residence time is not well constrained.     

Intermediate-scale sea ice — Atmosphere interactions over high southern latitudes in winter

Associations between polar air cloud vortices (polar lows), as an indicator of intermediate-scale atmospheric activity, and the Antarctic sea ice, are examined for the Southern Hemisphere winter (June–September). Seven consecutive winters, spanning a period of marked interannual variability of the atmospheric circulation and sea ice (1977–83), are analyzed using sets of DMSP (Defense Meteorological Satellite Program) imagery. Relatively high frequencies of polar lows are found in ice-edge and adjacent ocean latitudes. There is some evidence for an equatorward shift in the latitude of maximum monthly polar low occurrence during the June to September period. Polar low incidence over the Southern Hemisphere on interannual time scales shows a close association with positive sea ice anomalies in the longitudes of more frequent cold air outbreaks from higher latitudes. This is particularly apparent for winters of strongly anomalous circulation, such as FGGE (1979) and the major ENSO of 1982–83. However, for individual cases on daily to weekly time scales, the feedback of cold air — sea ice advance — polar low development is not always evident, and implies that additional processes may contribute to polar air cyclogenesis in the marginal ice zone.     

Using the General Lake Model (GLM) to simulate water temperatures and ice cover of a medium-sized lake: a case study of Lake Ammersee,Germany

Thermal dynamics of lakes has a key role in chemical and biological processes in lakes including nutrient distributions and phytoplankton growth. Applications of hydrodynamic models to lakes can provide insights into possible future alterations in thermal dynamics induced by climate change. In this study, we present the calibration and validation of the newest version of the open-source hydrodynamic model GLM (General Lake Model) to the dimictic Lake Ammersee, located in south-east Germany. The simulation of lake water temperatures for the calibration period revealed an overall root mean square error of 0.65 °C and a mean error of 0.08 °C. The seasonal stratification pattern and the annual thermal structure of this dimictic lake were reproduced by the model. The model simulated the presence of winter ice cover for the only year out of 8 years simulated, when ice cover was observed. Elevated lake water temperatures were also reproduced in model simulations during a period in 2003 of unusually high air temperatures. Statistical analysis of the model calibration results for Lake Ammersee indicates a fit comparable to or better than most other well-established hydrodynamic models and provides an opportunity for continuous simulations through periods of ice cover. Our results indicate a major improvement in GLM compared with earlier model versions and demonstrate the applicability of GLM for limnophysical studies, particularly for altered forcing conditions such as climate change.     

Lake stratigraphy implies an 80 000 yr delayed melting of buried dead ice in northern Russia

Sediment cores from lakes Kormovoye and Oshkoty in the glaciated region of the Pechora Lowland, northern Russia, reveal sediment gravity flow deposits overlain by lacustrine mud and gyttja. The sediments were deposited mainly during melting of buried glacier ice beneath the lakes. In Lake Kormovoye, differential melting of dead ice caused the lake bottom to subside at different places at different times, resulting in sedimentation and erosion occurring only some few metres apart and at shifting locations, as further melting caused inversion of the lake bottom. Basal radiocarbon dates from the two lakes, ranging between 13 and 9 ka, match with basal dates from other lakes in the Pechora Lowland as well as melting of ice‐wedges. This indicates that buried glacier ice has survived for ca. 80 000 years from the last glaciation of this area at 90 ka until about 13 ka when a warmer climate caused melting of permafrost and buried glacier ice, forming numerous lakes and a fresh‐looking glacial landscape. Copyright © 2003 John Wiley & Sons, Ltd.     

冰川冰内及冰下水系研究综述

冰内及冰下水系的形成与演化具有时空变化性,对冰川汇水储水及径流过程产生影响,与之紧密联系的冰下水文过程(水力状况)与冰川运动、冰川侵蚀及冰川洪水形成等过程息息相关。冰内及冰下水系空间结构和形态复杂,且不同于一般喀斯特水文系统,具有明显的季节变化性,其空间分布和水力状况会因外界水体输入(降水和冰雪融水)的变化而改变。冰内及冰下水系的变化通过影响汇流对冰川融水的径流过程产生影响,冰川区一些溃决洪水事件的发生与冰内及冰下蓄水的突然释放有很大关系。冰川蓄排水还通过改变冰下水力条件来影响冰川运动,反之冰川运动不仅影响蓄排水过程的转换效率,且通过改变冰川消融强度(冰体向下游消融区输送速率的变化)影响冰川排水系统的空间分布范围。在气候变暖及冰川变化的背景下,研究冰内冰下水系演化的时空特征及其影响具有重要科学意义。综述了目前国内外针对冰川冰内及冰下水系相关研究的进展及主要成果,并对该领域的研究前景进行了展望。