The ice thermal parameters are the key to reasonably simulating ice phenology, distribution, and thickness, but they have always been a “vulnerable group” in ice research. Technically, it may seem simple to obtain accurate ice thermal property parameters, but in reality, there are numerous impact factors, requiring a rigorous research process. In the 1980s, the thermal conductivity of ice was explored in the field and laboratory, after which there has been no significant progress in China. In this century, mathematics is introduced, after which the inversion identification and analysis with the time-series data of the vertical temperature profiles of ice layers by in situ testing are carried out. The in situ thermal diffusivities of different natural ices were obtained and cross-validated with the inversion identification results. Both natural freshwater ice and sea ice exhibited differences in the thermal diffusivity of the pure ice chosen for the current simulations due to impurities within the unfrozen water among the ice crystals, but the trends are consistent with the results of a small number of laboratory tests on different types of saltwater frozen ice. In this paper, the inversion identification results of the thermal diffusivity of typical ice were selected, and the factors constraining the thermal diffusivities were analyzed. The importance of parameterizing the thermal diffusivity in the phase transition zone of ice under the trend of global warming was illustrated. Future research ideas on the physical mechanism, application value, and parameterization scheme of the thermal diffusivity of natural ice were envisaged.

The surface morphology of lake ice remarkably changes under the combined influence of thermal and mechanical forces. However, research on the surface morphology of lake ice and its interaction with climate is scarce. A large-scale linear structure has repeatedly appeared on satellite images of Chagan Lake in recent years. The Geostationary Ocean Color Imager (GOCI), with a 1 h revisit, and Landsat 8 Operational Land Imager (OLI), with a spatial resolution of 30 m, provide the possibility for the study of hourly changes in the large-scale linear structure. We merged the Landsat and GOCI images, using an Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM), and extracted the lengths and angles of the linear structure. We monitored the hourly changes in the surface morphology during the cold season from 2018 to 2019. The average length of the linear structure in the completely frozen period was 21 141.57 ± 68.36 m. The average azimuth angle was 335.48 ± 0.23∘, nearly perpendicular to the domain wind in winter. Through two field investigations during the two recent cold seasons, we verified the linear structure as being ice fractures and ridges. The evolution of surface morphology is closely associated with air temperature, wind, and shoreline geometry.

Unfrozen free and non-free water between ice crystals in flat and hummock ice in the Yellow River exists as water films with varying contents based on ice temperature. These contents can affect the radar wave velocity of the ice despite its theoretical dependence on the crystal structure and ice body components. The unfrozen water content in ice depends on the ice temperature, which is controlled by the air temperature, solar radiation, and ice thickness. Winter air temperature and radar-detected ice thickness data observed at the Shisifenzi bend in the Yellow River from 2020 to 2021 were analyzed. The unfrozen water content in the ice was the primary factor influencing the accuracy of flat ice thickness detection. The heat flux at the ice–water interface in the Yellow River was determined. The evolution of ice thickness and temperature were simulated using a one-dimensional (1D) ice thermodynamic model forced by the local weather station data (i.e., air temperature, solar radiation, wind speed, and cloud cover). On this basis, the measured ice thickness data of 13 drill holes were combined to calculate 1251 thermodynamically simulated ice thicknesses consistent with the ice thickness detection time of the radar; therefore, statistical relationships regarding the influence of air temperature and the combined action of air temperature and ice thickness on the radar wave velocity in granular and columnar ice during air temperature increases and decreases were determined. Finally, the statistical relationship between the combined influence of air temperature and ice thickness on radar wave velocity was selected as a parameterization scheme to dynamically correct the radar wave velocity of flat ice. To enhance the radar detection accuracy for flat ice thickness, the radar wave velocity of ice was parameterized as a function. Given the presence of unfrozen frazil ice and accumulated broken ice blocks in the Yellow River, radar is suggested to detect the thickness of different types of ice in future research.

Lake ice phenology affects the lake environment and lake-air interaction through the ice-covered period. In order to investigate the trends and influencing factors of lake ice phenology in freshwater lakes on the Tibetan Plateau, the FLake model was employed after improvement. The model validation used MODIS surface temperature data based reconstruction of the ice-on date time series in 1979—2021 for Lakes Ngoring and Gyaring. Sensitivity experiments were conducted using the improved model. The results showed that the present FLake-SELF model improved the accuracy of the ice-on date calculation by 35%,and the reconstructed sequences showed that the ice-on dates of Lakes Ngoring and Gyaring have been delayed by 4.5 d/（10 a） and 3.8 d/（10 a）,respectively. Increasing air temperature, decreasing wind speed, and increasing vapor pressure are the most important meteorological factors leading to the delay of ice-on date, and interannual variability in these factors were the most important reasons for the interannual fluctuations of ice-on dates in the two lakes. In the same climate conditions, the different lake depth was the reason for the differences in ice-on date and their delay rate between the two lakes. The deeper the lake was, the greater was the interannual fluctuation in ice-on date, the greater was the rate of change of ice-on date, and the more sensitive was the ice-on date to climate change.

为探究寒旱区浅湖冰封期分层动态与其对湖泊新陈代谢速率的影响,于2016-2019年对乌梁素海气象与冰雪条件、冰下水体环境开展原位观测,分析水温和溶解氧变化特征、冰下混合层的出现与发展动态及其对代谢速率的影响.结果显示:观测期内乌梁素海整体水温较高(可接近10℃),冻结期水温结构主要由稳定的上部逆温层和下部弱逆温层构成,并可逐渐过渡为融化期的上部逆温层-下部混合层结构;溶解氧由上到下衰减,甚至在底部形成缺氧区域(＜2 mg/L);受盐度影响,乌梁素海中下层水温升高至一定阈值(约6～8℃)后形成冰下混合层并随辐射增加快速发展;溶解氧动态由光合产氧与呼吸耗氧平衡决定,光合和呼吸速率的时间变化主要受冰雪条件、透射辐射、水温和混合过程影响;特别是,混合过程极大地促进了光合产氧和呼吸耗氧速率,调控了水温与溶解氧结构动态.

Optimal identification and numerical models are powerful tools that have been widely used in geoscience research for many years. In this study, we proposed a novel optimal method to simulate a key parameter (cutoff draft) of the ridge keels due to dynamic deformation of sea ice at bottom. The sea ice ridges were measured in the Northwestern Weddell Sea of Antarctic, by a helicopter-borne electromagnetic-induction (EM) system. An optimal model with nonlinear-statistical constraints was developed, by taking deviations between the theoretical and measured keel draft (spacing) distributions as the performance criterion, and cutoff draft as the identified parameter. The properties of the optimal model and the existence of the optimal parameter were demonstrated. We identified that the optimal cutoff draft was 3.78 m via an optimal numerical algorithm, this value was then employed to separate the ridge keels from the ice bottom. Finally, the relationship between the mean keel draft and frequency (number of keels per km) was analyzed, and the result showed that this relationship was modeled well by a logarithmic function with a correlation coefficient of 0.7. The present optimal modeling method will provide a new theoretical reference for separating accurately the ridge keels from undeformed sea ice bottom, and analyzing the relationship between the morphologies of sea ice surface and bottom and the inversions of sea ice bottom draft and ice thickness by the surface height.

黄河平封冰和立封冰中冰晶体间以水膜形式存在有未冻结的自由水和非自由水,其含量随冰温变化.理论上冰内雷达波速取决于冰体自身的晶体结构和组分,但冰内未冻水含量可对其产生明显的影响;冰内未冻水含量取决于冰温,冰温又受控于气温、辐射和冰厚.分析了黄河什四份子2020—2021年冬季气温和雷达探测冰厚数据,发现气温主导的未冻水含量变化是影响雷达准确探测平封冰厚度的首要因子.通过确定黄河冰-水界面热通量,并引入含有气温、辐射、风速、云量的一维冰热力学模型,结合13个钻孔实测冰厚,计算了与雷达探测冰厚时刻一致的1251个热力学模拟冰厚.在此基础上,分别获得了气温升高过程和降低过程中粒状冰、柱状冰内雷达波速受气温影响以及受气温和冰厚联合影响的统计关系.最终确定将气温和冰厚对雷达波速联合影响的统计关系作为平封冰雷达波速动态修正的参数化方案,依此将固定式雷达冰内雷达波速由常数更换为函数,从而提高了平封冰雷达冰厚探测的精度.根据黄河存在非冻结冰花和堆积碎冰块,建议开展不同类型冰厚探测研究.

破冰船在破冰航行过程中与冰的作用速度已经超出了传统冰压缩强度试验的范围,为探究撞击作用下冰的破坏机制,于2019—2020年冬季在辽东湾滨海咸水湖取冰,使用自行研发的冰冲击试验机分别在5种冲击速度(1.2、2.5、3.1、3.6、3.9 m/s)、3种冲击头形状(圆盘形、半球形、楔形)以及9种冲击头尺寸(每种形状的冲击头直径或底边长3、5、7 cm)条件下对2种尺寸的冰样(7 cm×7 cm×17.5 cm,13 cm×13 cm×17.5 cm)开展了冲击试验研究.结果验证了试验设备和测试技术的可行性,同时表明大截面冰样受冲击后破坏程度较低,而所承受的冲击荷载较大.冲击头形状是影响冰样破坏形式的重要因素,在冲击动能和试样尺寸一致时,形状导致的试样破坏越严重,冲击荷载将越小.而对于同种类型冲击头而言,冲击速度较小时,冰样无明显破坏,冲击荷载随冲击速度增加而增加;当冲击速度较高时,冰样发生明显破坏,冲击荷载随速度的增加反而减小.

为在自然条件下实尺度测试"雪龙2"号的破冰能力,2019年11月"雪龙2"号在南极首航期间,中国在南极考察站——中山站附近普里兹湾固定冰区,首次自主开展了一系列专业破冰试验.通过选取破冰区域、实地测量冰雪厚度、钻采冰芯测量冰温度和盐度、切取完整冰坯并加工冰梁,完成了冰弯曲强度试验和艏艉双向破冰时的实船数据测量,首次获取了中山站附近固定冰的弯曲强度力学特性,成功验证了"雪龙2"号的破冰能力.本文详细介绍了"雪龙2"号现场破冰试验,并根据测量的海冰特性和船舶破冰航行数据对其艏向破冰能力进行了初步评估,摸索了一套在极地冰区开展破冰船破冰试验的方法,同时也对现场破冰试验中需要改进的方向提出了思考,可为我国新的破冰船建设提供参考.

为了解黄河干流同一断面冰厚增长差异及其产生原因,依据2019—2020年度冬季对头道拐断面封冻期原型观测数据,分析冰厚增长方式以及负积温、流速、冰花等对冰厚增长的影响.结果表明:头道拐断面冰层上层由冰花冻结形成;距左岸400～500 m为非主流区且区间内测点的冰生长方式为热力学生长,主要形成柱状冰;距左岸500～740 m为主流区且区间内测点的冰生长方式以冰花堆积冻结为主,测点之间的冰厚差异大.随着冰厚的不断增长,冰厚单位度日增长量逐渐减小;冰层底部有冰花堆积的冰厚单位度日增长量大于无冰花堆积的情况;当冰厚增长到一定厚度时,有冰花和无冰花的冰厚单位度日增长量趋于一致.负积温是冰厚增长的主要影响因素,流速对冰厚增长有抑制作用,冰层底部存在冰花对冰厚增长有促进作用.

基于2003—2018年中国第二次至第九次北极科考中获取的走航船基图像数据对北极夏季太平洋扇区沿航线平整冰厚度的时空变化进行了统计分析.结果显示太平洋扇区在夏季融冰期沿航线海冰厚度主要分布在10～280 cm区间,各航次存在一定差异但海冰厚度均近似呈正态分布.8月上旬和中旬沿航线平均冰厚均以-2 cm·a-1的梯度逐年减少.楚科奇海、波弗特海和北冰洋中央海域等各个子区域沿航线平均冰厚随年份线性减少的趋势均不显著.2°为间隔的不同纬度区间沿航线海冰厚度也近似呈正态分布,但集中分布范围存在差异.8月上旬和下旬的沿航线平均冰厚分别以2 cm·deg-1和5 cm·deg-1的梯度随纬度线性增加,北冰洋中央海域沿航线平均冰厚随纬度线性增加的趋势在各子区域中最为显著.

河冰的断裂性能是衡量河冰承载力、模拟和预测开河的重要参数.为明晰黄河冰的断裂性能,基于数字图像测量技术(Digital Image Correlation,DIC)开展了黄河冰的三点弯曲梁试验,分析了不同条件下试样的断裂形态,研究了温度和加载速率对黄河冰断裂韧度的影响.研究结果表明:DIC方法适用于黄河冰断裂试验的研究;黄河冰试样的断裂形态主要受到晶体形态的影响,试样的破坏形式以I型断裂为主;黄河冰断裂韧度随着加载速率的增加而降低,随着温度的升高而减小,但在试验给定温度范围内降幅较小;提出了黄河冰断裂韧度与温度、加载速率的关系式,为极限荷载作用下河冰断裂过程的分析及冰荷载断裂参数的选用提供了依据.

The Mongolian Plateau is characterized by cold and arid winters with very little precipitation (snowfall), strong solar insolation, and dry air, but little is known about the thermal regimes of the ice and ice-covered lakes and their response to the distinct weather and climate in this region. In a typical large, shallow lake, ice and snow processes (cover) and under-ice thermodynamics were monitored for four winters in 2015–2019. Heat transfer at the ice–water interface and lake heat budget were investigated. The results revealed that persistent bare ice of 35–50 cm thickness transmits 20 %–35 % of the incident solar radiation into the water below. This is a dominant source for under-ice energy flows and causes/maintains high water temperature (up to 6–8 ∘C) and high heat flux from water to ice (averages of 20–45 W m−2) in mid-winter, as well as higher heat conduction in the ice interior during freezing. The heat balance shows that the transmitted radiation and the heat flux from water to ice are the dominant and highly correlated heat flows in the lake. Both bulk water temperature and temperature structure are sensitive to solar transmittance and occasional snow events. Under-ice convective mixing does not necessarily occur because of stratification of salinity in the water body. In particular, salt exclusion during freezing changes both the bulk salinity and the salinity profile, which plays a major role in the stability and mixing of the water column in this shallow lake.

极地海冰形态在风、流、浪等外界驱动力的作用下不断发生变化,观测极地海冰底面形态特征并分析其变化规律,有助于基于海冰粗糙度信息的冰厚遥感算法和海冰热动力学数值模拟参数化方案的优化,对深入理解极地海冰特征对气候变化的响应有重要意义.首先,基于机载电磁感应系统测得的南极威德尔海西北区域2006年冬季海冰底面起伏数据,建立以龙骨切断深度为辨识参数的非线性统计优化模型,从海冰底面形态中明确区分出局部起伏和龙骨;然后,利用统计方法分析龙骨形态参数,并对龙骨深度和频次的相关性进行分析;最后,通过构造的新参数T分析龙骨深度与脊帆高度之间的相关性.结果 表明,威德尔海西北区域海冰的龙骨最优切断深度为3.8m,龙骨间距是影响强度的主要因素;虽然不同类别海冰的变形程度差异显著,但龙骨形状变化却并不明显;龙骨深度与频次之间的对数相关关系能够很好地刻画龙骨的形态和分布特征;新参数丁与龙骨深度之间存在较强的线性相关关系,相关系数为0.93.所提出的龙骨切断深度确定方法能够更精确地从海冰底面起伏中分离出龙骨,为海冰表面和底面形态相关性研究以及利用海冰表面高度反演底面深度和冰厚提供进一步的理论参考依据.

冰的细观结构决定了其物理力学性质,为掌握黄河内蒙古河段河冰晶体结构的变化特征,应用数字图像方法对黄河冰晶体图像进行分析,使用Canny算子对冰晶粒的边界进行提取,得到冰晶粒完整的边界信息,基于连通区域原理统计冰晶图像中每个冰晶粒的尺寸,分析冰晶等效直径的分布规律.结果表明:不同粒径的冰晶粒占总晶粒的比例随着等效直径的增大呈现先增大后减小的趋势,等效直径为3～6 mm的晶粒占比最高;晶粒的垂直分布与冰胚的晶体结构密切相关,粒径随着粒状冰与柱状冰层的交替出现而不断变化.

极地海冰是地球气候系统的重要组成部分,也是气候环境变化的指示器和放大器.极地海冰复杂的多尺度物理过程和极地观测资料的匮乏,给海冰模式的研发带来了巨大的挑战.在过去的半个多世纪中,大气-海冰-海洋的复杂相互作用和冰内物理过程在海冰模式中的数学描述取得了重大的进展,但海冰模式对一些重要物理过程的描述仍很不完善,尤其是近年来极地海冰的快速变化及其物理特性的变化,极大地增加了海冰模式物理参数化方案和模拟结果的不确定性.因此,迫切需要具备完善物理过程、适应海冰多尺度快速变化的高分辨率海冰模式,并应用于全球气候变化的研究和预测以及极地的开发利用.本文从海冰模式的发展历程和现状、极地海冰快速变化给海冰模式带来的挑战以及适应极地快速变化海冰模式的改进和发展研究方向三个方面进行了阐述和讨论.

冰冻圈与气候变化、人类工程活动和社会经济发展具有极为密切的关系,冰冻圈变化及其引发的冰冻圈灾害使寒区工程建设和安全运营面临着巨大的挑战.冰冻圈各要素对重大工程影响具有显著不同的特点,冰川、积雪、海(河、湖)冰等主要以灾害方式影响重大工程的建设、安全运营和服役性.冻土作为工程构筑物的特殊地基土,冻融灾害和冻土热力学稳定性变化均会直接影响工程的稳定性.随着全球气候环境变化,冰冻圈各要素变化及其水文、生态环境、地表过程等变化均对重大工程产生显著的影响,需加强重大工程建设和安全运营与环境因素变化之间关系研究,重大工程安全保障技术也需更加综合地考虑气候和环境变化的影响.因此,气候和环境变化将成为未来冰冻圈区重大工程建设、安全运营和工程服役性必须考虑的重要因素.同时, “一带一路”基础设施建设不仅给冰冻圈工程学带来机遇,而且也使其面临更大的挑战.

为了认识冰内气泡和未冻水的空间分布及形态特征,用Philips Brilliance 16 CT扫描实验机探测了乌梁素海2根冰样的内部组构,同时还实测了冰样密度和晶体结构.结果显示现场宏观判断含气泡多的冰样(W 1)和含气泡少的冰样(W2)在冰密度和晶体结构基本无区别.但冰样W2各层的CT值稳定在-85～-65 HU之间,冰样W1各层的CT值在-150～-110 HU范围波动.对扫描截面影像像素体单元的CT值统计发现:(1)CT值能够体现冰样W1中冰内直径大于1 mm的气泡,探测到的CT值在-250～-150 HU之间;(2)对冰样W1冰内直径小于C T分辨率0.19 m m的气泡,在影像中不能直观发现,但其C T值在-150～-110 H U之间,可以理论计算气泡的体积比;(3)冰样W1存在少量未冻水位置的CT影像中更难发现,但扫描截面中出现局部CT值升高,也可以结合理论分析计算或利用更高分辨率的CT扫描设备解决.

由于以往溶解氧的测定多在开阔常温水体进行,对冰下水体的环境重视不足,国内还没有形成测试规程.本文首先阐述针对浅水湖泊的水体内和冰下泥-水界面的耗氧过程的测试技术.之后介绍冰下水体分层耗氧量过程在线测试装置,该装置采用冰下施放、可盲视操作,令上下盖自动闭合,避免容器取出冰面,因冻结对传感器和容器的正常工作产生不利影响,此外,该设计装置能在冰层分层测试水体耗氧过程.以上特点保障该装置在冬季冰下测试中具有实际应用价值.

在2017-2018年冬季使用无人机对乌梁素海湖冰的冰面裂缝进行了航拍,采用改进的自适应阈值分割方法进行图像二值化处理,提取了冰裂缝的密度和分形维数.分析结果显示:在固定区域的冰裂缝分形维数在1.35～1.50间变化,冰裂缝数量随时间增加,其分形维数也随之线性增大;在冰生长期间,冰厚度与冰裂缝分形维数也呈现出明显的线性关系(相关系数R2=0.75).冰面不同区域的冰裂缝密度和分形维数在0.017～0.079、1.38～1.64间变化,且两者之间存在显著的对数相关性(相关系数R2>0.96),不同日期航拍数据拟合结果近似相等,说明冰裂缝密度越大,对应的分形维数越大.作为表征冰面形态特征的一种物理指标,建立得到的冰裂缝分形维数与冰厚、裂缝密度的相关关系,对未来利用冰面裂缝形态监测冰层的生消过程可提供科学的参考.