首页 > 最新文献

Journal of Glaciology最新文献

英文 中文
Constraints on subglacial melt fluxes from observations of active subglacial lake recharge 冰下活湖补给观测对冰下融水通量的制约
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-26 DOI: 10.1017/jog.2023.70
George Malczyk, Noel Gourmelen, Mauro Werder, Martin Wearing, Dan Goldberg
Abstract Active subglacial lakes provide a rare glimpse of the subglacial environment and hydrological processes at play. Several studies contributed to establishing active subglacial lake inventories and document lake drainage and connection, but few focused on the period between lake drainage when the melt production and transport contribute to the refilling of these lakes. In this study, we employ high-resolution CryoSat-2 altimetry data from 2010 to 2021 to compile an inventory of recharging lakes across Antarctica. We extract recharge rates from these lakes, which serve as a lower limit on subglacial melt production. These recharge rates are compared against predictions obtained by routing modelled subglacial meltwater at the ice-sheet's base. Our findings indicate that modelled recharge rates are consistent with observations in all but one of the investigated lakes, providing a lower bound on geothermal heat fluxes. Lake Cook E2 displays recharge rates far exceeding predictions, indicating that processes are taking place that are currently unaccounted for. Considering recharge in hydrologically connected lake networks instead of individually provides a stricter constraint on melt production. Recharge rates extracted from the Thwaites Lake system suggest that subglacial melt production has been underestimated.
活跃的冰下湖泊提供了对冰下环境和水文过程的罕见一瞥。一些研究有助于建立活跃的冰下湖泊清单,并记录湖泊的排水和联系,但很少关注湖泊排水之间的时间,当融水的产生和运输有助于这些湖泊的补充。在这项研究中,我们使用了2010年至2021年的高分辨率CryoSat-2测高数据来编制南极洲各地补给湖的清单。我们从这些湖泊中提取补给速率,作为冰下融水产生的下限。这些补给速率与通过在冰盖底部模拟冰下融水得到的预测结果进行了比较。我们的研究结果表明,模拟的补给率与除一个外的所有调查湖泊的观测结果一致,提供了地热通量的下限。库克湖E2显示的补给率远远超过预测,表明目前尚未解释的过程正在发生。考虑在水文上相连的湖泊网络中而不是单独考虑补给,对熔体的产生提供了更严格的限制。从斯韦茨湖系统提取的补给速率表明,冰下融水的产生被低估了。
{"title":"Constraints on subglacial melt fluxes from observations of active subglacial lake recharge","authors":"George Malczyk, Noel Gourmelen, Mauro Werder, Martin Wearing, Dan Goldberg","doi":"10.1017/jog.2023.70","DOIUrl":"https://doi.org/10.1017/jog.2023.70","url":null,"abstract":"Abstract Active subglacial lakes provide a rare glimpse of the subglacial environment and hydrological processes at play. Several studies contributed to establishing active subglacial lake inventories and document lake drainage and connection, but few focused on the period between lake drainage when the melt production and transport contribute to the refilling of these lakes. In this study, we employ high-resolution CryoSat-2 altimetry data from 2010 to 2021 to compile an inventory of recharging lakes across Antarctica. We extract recharge rates from these lakes, which serve as a lower limit on subglacial melt production. These recharge rates are compared against predictions obtained by routing modelled subglacial meltwater at the ice-sheet's base. Our findings indicate that modelled recharge rates are consistent with observations in all but one of the investigated lakes, providing a lower bound on geothermal heat fluxes. Lake Cook E2 displays recharge rates far exceeding predictions, indicating that processes are taking place that are currently unaccounted for. Considering recharge in hydrologically connected lake networks instead of individually provides a stricter constraint on melt production. Recharge rates extracted from the Thwaites Lake system suggest that subglacial melt production has been underestimated.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134960933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Ice-flow model emulator based on physics-informed deep learning 基于物理信息深度学习的冰流模型仿真器
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-26 DOI: 10.1017/jog.2023.73
Guillaume Jouvet, Guillaume Cordonnier
Abstract Convolutional neural networks (CNN) trained from high-order ice-flow model realisations have proven to be outstanding emulators in terms of fidelity and computational performance. However, the dependence on an ensemble of realisations of an instructor model renders this strategy difficult to generalise to a variety of ice-flow regimes found in the nature. To overcome this issue, we adopt the approach of physics-informed deep learning, which fuses traditional numerical solutions by finite differences/elements and deep-learning approaches. Here, we train a CNN to minimise the energy associated with high-order ice-flow equations within the time iterations of a glacier evolution model. As a result, our emulator is a promising alternative to traditional solvers thanks to its high computational efficiency (especially on GPU), its high fidelity to the original model, its simplified training (without requiring any data), its capability to handle a variety of ice-flow regimes and memorise previous solutions, and its relatively simple implementation. Embedded into the ‘Instructed Glacier Model’ (IGM) framework, the potential of the emulator is illustrated with three applications including a large-scale high-resolution (2400x4000) forward glacier evolution model, an inverse modelling case for data assimilation, and an ice shelf.
从高阶冰流模型实现中训练的卷积神经网络(CNN)在保真度和计算性能方面已被证明是出色的模拟器。然而,依赖于讲师模型的整体实现使得该策略难以推广到自然界中发现的各种冰流状态。为了克服这个问题,我们采用了基于物理的深度学习方法,它融合了基于有限差分/元素的传统数值解和深度学习方法。在这里,我们训练CNN在冰川演化模型的时间迭代中最小化与高阶冰流方程相关的能量。因此,我们的模拟器是传统求解器的一个有前途的替代品,这要归功于它的高计算效率(特别是在GPU上),对原始模型的高保真度,简化的训练(不需要任何数据),处理各种冰流状态和记忆以前的解决方案的能力,以及相对简单的实现。嵌入到“指示冰川模型”(IGM)框架中,仿真器的潜力通过三个应用程序进行说明,包括大规模高分辨率(2400x4000)正向冰川演化模型,数据同化的逆建模案例和冰架。
{"title":"Ice-flow model emulator based on physics-informed deep learning","authors":"Guillaume Jouvet, Guillaume Cordonnier","doi":"10.1017/jog.2023.73","DOIUrl":"https://doi.org/10.1017/jog.2023.73","url":null,"abstract":"Abstract Convolutional neural networks (CNN) trained from high-order ice-flow model realisations have proven to be outstanding emulators in terms of fidelity and computational performance. However, the dependence on an ensemble of realisations of an instructor model renders this strategy difficult to generalise to a variety of ice-flow regimes found in the nature. To overcome this issue, we adopt the approach of physics-informed deep learning, which fuses traditional numerical solutions by finite differences/elements and deep-learning approaches. Here, we train a CNN to minimise the energy associated with high-order ice-flow equations within the time iterations of a glacier evolution model. As a result, our emulator is a promising alternative to traditional solvers thanks to its high computational efficiency (especially on GPU), its high fidelity to the original model, its simplified training (without requiring any data), its capability to handle a variety of ice-flow regimes and memorise previous solutions, and its relatively simple implementation. Embedded into the ‘Instructed Glacier Model’ (IGM) framework, the potential of the emulator is illustrated with three applications including a large-scale high-resolution (2400x4000) forward glacier evolution model, an inverse modelling case for data assimilation, and an ice shelf.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134904239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Seasonal changes in submarine melting mechanisms controlling frontal ablation of Hansbreen, Svalbard 控制斯瓦尔巴群岛汉斯布林锋面消融的海底融化机制的季节变化
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-26 DOI: 10.1017/jog.2023.69
Michał Ciepły, Dariusz Ignatiuk, Mateusz Moskalik, Jacek Jania, Bartłomiej Luks, Oskar Głowacki, Kacper Wojtysiak
Abstract We describe the annual pattern of frontal ablation driven by submarine melting mechanisms at the Hansbreen terminus: these are reflected in the intensity and spatial distribution of calving events. Analysis of time-lapse images of the Hansbreen front in conjunction with oceanographic and meteorological data shows that calving intensity is driven primarily by seawater temperature. Regression analysis also highlights the importance of air temperature, which we take to be a proxy for surface ablation and subglacial discharge. This, combined with seasonal changes in ice cliff tortuosity and the increasing significance of wave motion outside the ablation season, enabled us to determine seasonal changes in the mechanisms of ice cliff undercutting by submarine melting. While submarine melting controlled by estuarine circulation primarily drives frontal ablation in summer, wave-driven melting at the waterline is more important outside the ablation season. During winter, ice cliff undercutting by melting is suspended by low seawater temperature, negligible subglacial water discharge and sea-ice cover. The most intense frontal ablation, recorded in summer, was related to higher sea temperature and vigorous estuarine circulation.
我们描述了在汉斯布林末端海底融化机制驱动的锋面消融的年模式:这些模式反映在产冰事件的强度和空间分布上。结合海洋学和气象资料,对汉斯布林锋的延时图像进行分析,表明产犊强度主要是由海水温度驱动的。回归分析还强调了气温的重要性,我们认为气温是地表消融和冰下流量的代表。结合冰崖弯曲度的季节变化和消融季节之外波浪运动的日益重要的意义,使我们能够确定海底融化冰崖破坏机制的季节变化。在夏季,由河口环流控制的海底融化主要驱动锋面消融,而在消融季节之外,波浪驱动的水线融化更为重要。在冬季,由于海水温度较低,冰下水量和海冰覆盖可忽略不计,冰崖的融化被暂停。记录到的最强烈的锋面消融发生在夏季,与较高的海温和旺盛的河口环流有关。
{"title":"Seasonal changes in submarine melting mechanisms controlling frontal ablation of Hansbreen, Svalbard","authors":"Michał Ciepły, Dariusz Ignatiuk, Mateusz Moskalik, Jacek Jania, Bartłomiej Luks, Oskar Głowacki, Kacper Wojtysiak","doi":"10.1017/jog.2023.69","DOIUrl":"https://doi.org/10.1017/jog.2023.69","url":null,"abstract":"Abstract We describe the annual pattern of frontal ablation driven by submarine melting mechanisms at the Hansbreen terminus: these are reflected in the intensity and spatial distribution of calving events. Analysis of time-lapse images of the Hansbreen front in conjunction with oceanographic and meteorological data shows that calving intensity is driven primarily by seawater temperature. Regression analysis also highlights the importance of air temperature, which we take to be a proxy for surface ablation and subglacial discharge. This, combined with seasonal changes in ice cliff tortuosity and the increasing significance of wave motion outside the ablation season, enabled us to determine seasonal changes in the mechanisms of ice cliff undercutting by submarine melting. While submarine melting controlled by estuarine circulation primarily drives frontal ablation in summer, wave-driven melting at the waterline is more important outside the ablation season. During winter, ice cliff undercutting by melting is suspended by low seawater temperature, negligible subglacial water discharge and sea-ice cover. The most intense frontal ablation, recorded in summer, was related to higher sea temperature and vigorous estuarine circulation.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134958164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Simulating the processes controlling ice-shelf rift paths using damage mechanics 用损伤力学模拟控制冰架断裂路径的过程
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-21 DOI: 10.1017/jog.2023.71
Alex Huth, Ravindra Duddu, Benjamin Smith, Olga Sergienko
Abstract Rifts are full-thickness fractures that propagate laterally across an ice shelf. They cause ice-shelf weakening and calving of tabular icebergs, and control the initial size of calved icebergs. Here, we present a joint inverse and forward computational modeling framework to capture rifting by combining the vertically integrated momentum balance and anisotropic continuum damage mechanics formulations. We incorporate rift–flank boundary processes to investigate how the rift path is influenced by the pressure on rift–flank walls from seawater, contact between flanks, and ice mélange that may also transmit stress between flanks. To illustrate the viability of the framework, we simulate the final 2 years of rift propagation associated with the calving of tabular iceberg A68 in 2017. We find that the rift path can change with varying ice mélange conditions and the extent of contact between rift flanks. Combinations of parameters associated with slower rift widening rates yield simulated rift paths that best match observations. Our modeling framework lays the foundation for robust simulation of rifting and tabular calving processes, which can enable future studies on ice-sheet–climate interactions, and the effects of ice-shelf buttressing on land ice flow.
裂缝是沿冰架横向传播的全层裂缝。它们造成冰架的削弱和板状冰山的崩解,并控制崩解冰山的初始大小。在这里,我们提出了一个联合的逆正演计算模型框架,通过结合垂直积分动量平衡和各向异性连续损伤力学公式来捕捉裂谷。我们结合裂谷-翼面边界过程来研究裂谷路径如何受到来自海水的裂谷-翼面壁面压力、侧翼之间的接触以及可能在侧翼之间传递应力的冰的影响。为了说明该框架的可行性,我们模拟了与2017年A68平板冰山崩解相关的最后2年裂缝传播。研究发现,裂谷路径会随着冰缘条件和裂谷两侧接触程度的变化而变化。与较慢的裂谷扩大速率相关的参数组合产生了与观测结果最匹配的模拟裂谷路径。我们的建模框架为裂谷和板状崩解过程的稳健模拟奠定了基础,这可以为未来研究冰盖-气候相互作用以及冰架支撑对陆地冰流的影响奠定基础。
{"title":"Simulating the processes controlling ice-shelf rift paths using damage mechanics","authors":"Alex Huth, Ravindra Duddu, Benjamin Smith, Olga Sergienko","doi":"10.1017/jog.2023.71","DOIUrl":"https://doi.org/10.1017/jog.2023.71","url":null,"abstract":"Abstract Rifts are full-thickness fractures that propagate laterally across an ice shelf. They cause ice-shelf weakening and calving of tabular icebergs, and control the initial size of calved icebergs. Here, we present a joint inverse and forward computational modeling framework to capture rifting by combining the vertically integrated momentum balance and anisotropic continuum damage mechanics formulations. We incorporate rift–flank boundary processes to investigate how the rift path is influenced by the pressure on rift–flank walls from seawater, contact between flanks, and ice mélange that may also transmit stress between flanks. To illustrate the viability of the framework, we simulate the final 2 years of rift propagation associated with the calving of tabular iceberg A68 in 2017. We find that the rift path can change with varying ice mélange conditions and the extent of contact between rift flanks. Combinations of parameters associated with slower rift widening rates yield simulated rift paths that best match observations. Our modeling framework lays the foundation for robust simulation of rifting and tabular calving processes, which can enable future studies on ice-sheet–climate interactions, and the effects of ice-shelf buttressing on land ice flow.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136155238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Examining the effect of ice dynamic changes on subglacial hydrology through modelling of a synthetic Antarctic glacier 通过模拟南极合成冰川考察冰动力变化对冰下水文的影响
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-21 DOI: 10.1017/jog.2023.65
Anna-Mireilla Hayden, Christine F. Dow
Abstract Hydrologic pathways beneath ice sheets and glaciers play an important role in regulating ice flow. Antarctica has experienced, and will continue to experience, changes in ice dynamics and geometry, but the associated changes in subglacial hydrology have received less attention. Here, we use the GlaDS subglacial hydrology model to examine drainage evolution beneath an idealised Antarctic glacier in response to steepening ice surface slopes, accelerating ice velocities and subglacial lake drainages. Ice surface slope changes exerted a dominant influence, redirecting basal water to different outlet locations and substantially increasing channelised discharge crossing the grounding line. Faster ice velocities had comparatively negligible effects. Subglacial lake drainage results indicated that lake refilling times play a key role in drainage system evolution, with lake flux more readily accommodated following shorter refilling times. Our findings are significant for vulnerable Antarctic regions currently experiencing dynamic thinning since subglacial water re-routing could destabilise ice shelves through enhanced sub-shelf melting, potentially hastening irreversible retreat. These changes could also affect subglacial lake activity. We, therefore, emphasise that including a nuanced and complex representation of subglacial hydrology in ice-sheet models could provide critical information on the timing and magnitude of sea-level change contributions from Antarctica.
冰盖和冰川下的水文通道在调节冰流中起着重要作用。南极洲已经经历并将继续经历冰的动力和几何形状的变化,但冰下水文的相关变化受到的关注较少。在这里,我们使用GlaDS冰下水文模型来研究理想南极冰川下的排水演变,以响应冰面斜坡变陡、冰速加速和冰下湖泊排水。冰面坡度的变化发挥了主导作用,将基底水重新定向到不同的出口位置,并大大增加了穿越接地线的渠化流量。相对而言,更快的冰速影响可以忽略不计。冰下湖泊排水结果表明,湖泊填填时间对流域系统演化起关键作用,填填时间越短,湖泊通量越容易被调节。我们的研究结果对目前正在经历动态变薄的脆弱南极地区具有重要意义,因为冰下水的重新输送可能通过加强冰下融化而破坏冰架的稳定,可能加速不可逆转的退缩。这些变化也可能影响冰下湖泊的活动。因此,我们强调,在冰盖模型中加入细致而复杂的冰下水文,可以提供关于南极对海平面变化贡献的时间和幅度的关键信息。
{"title":"Examining the effect of ice dynamic changes on subglacial hydrology through modelling of a synthetic Antarctic glacier","authors":"Anna-Mireilla Hayden, Christine F. Dow","doi":"10.1017/jog.2023.65","DOIUrl":"https://doi.org/10.1017/jog.2023.65","url":null,"abstract":"Abstract Hydrologic pathways beneath ice sheets and glaciers play an important role in regulating ice flow. Antarctica has experienced, and will continue to experience, changes in ice dynamics and geometry, but the associated changes in subglacial hydrology have received less attention. Here, we use the GlaDS subglacial hydrology model to examine drainage evolution beneath an idealised Antarctic glacier in response to steepening ice surface slopes, accelerating ice velocities and subglacial lake drainages. Ice surface slope changes exerted a dominant influence, redirecting basal water to different outlet locations and substantially increasing channelised discharge crossing the grounding line. Faster ice velocities had comparatively negligible effects. Subglacial lake drainage results indicated that lake refilling times play a key role in drainage system evolution, with lake flux more readily accommodated following shorter refilling times. Our findings are significant for vulnerable Antarctic regions currently experiencing dynamic thinning since subglacial water re-routing could destabilise ice shelves through enhanced sub-shelf melting, potentially hastening irreversible retreat. These changes could also affect subglacial lake activity. We, therefore, emphasise that including a nuanced and complex representation of subglacial hydrology in ice-sheet models could provide critical information on the timing and magnitude of sea-level change contributions from Antarctica.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136235761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Ground penetrating radar in temperate ice: englacial water inclusions as limiting factor for data interpretation 温带冰的探地雷达:冰川水包裹体作为数据解释的限制因素
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-21 DOI: 10.1017/jog.2023.68
Christophe Ogier, Dirk-Jan van Manen, Hansruedi Maurer, Ludovic Räss, Marian Hertrich, Andreas Bauder, Daniel Farinotti
Abstract Ground penetrating radar (GPR) has been extensively used in glaciology to infer glacier's ice thickness, liquid water content, water drainage pathways, and other properties. The interpretation of such GPR data is not always straightforward and for temperate glaciers, the signal is often affected by strong scattering and attenuation. It has often been suggested that such effects originate from englacial water inclusions, since water and ice have a large contrast in their di-electric permittivity. To investigate such effects quantitatively, we perform an extensive numerical modeling study of GPR signals. By exploring how different liquid water contents (LWC) and water-inclusions size affect the GPR signal, we show that their effects are much larger than the potential presence of a wet snowpack or a heterogeneous distribution of ice permittivity. In particularly, we show that the presence of such water inclusions is a necessary and sufficient condition for reproducing the typical characteristics of GPR data acquired in the field. Further, we find that for 25 MHz GPR antennas, a bulk LWC $gtrsim$ 0.2%, associated with decimeters-scale water inclusions already limits bedrock detectability for ice thicknesses $gtrsim 100$ m. Since these values are typical for Alpine glaciers, they clarify why the quality of GPR data is often poor in such environments.
摘要探地雷达(GPR)在冰川学中得到了广泛的应用,可以推断冰川的冰厚、液态水含量、排水路径等性质。这种探地雷达数据的解释并不总是直截了当的,对于温带冰川,信号经常受到强烈散射和衰减的影响。由于水和冰的介电常数有很大的差别,因此经常有人提出这种效应是由冰川的水包裹体引起的。为了定量研究这种影响,我们对探地雷达信号进行了广泛的数值模拟研究。通过探索不同液态水含量(LWC)和水包裹体大小对探地雷达信号的影响,我们发现它们的影响远远大于可能存在的湿积雪或冰介电常数的非均匀分布。特别是,我们表明,这种水包裹体的存在是再现在现场获得的GPR数据的典型特征的必要和充分条件。此外,我们发现,对于25 MHz GPR天线,大量LWC为0.2%,与分米尺度的水夹杂物相关,已经限制了基岩对冰厚度100 m的可探测性。由于这些值对于高山冰川来说是典型的,它们阐明了为什么GPR数据的质量在这种环境中往往很差。
{"title":"Ground penetrating radar in temperate ice: englacial water inclusions as limiting factor for data interpretation","authors":"Christophe Ogier, Dirk-Jan van Manen, Hansruedi Maurer, Ludovic Räss, Marian Hertrich, Andreas Bauder, Daniel Farinotti","doi":"10.1017/jog.2023.68","DOIUrl":"https://doi.org/10.1017/jog.2023.68","url":null,"abstract":"Abstract Ground penetrating radar (GPR) has been extensively used in glaciology to infer glacier's ice thickness, liquid water content, water drainage pathways, and other properties. The interpretation of such GPR data is not always straightforward and for temperate glaciers, the signal is often affected by strong scattering and attenuation. It has often been suggested that such effects originate from englacial water inclusions, since water and ice have a large contrast in their di-electric permittivity. To investigate such effects quantitatively, we perform an extensive numerical modeling study of GPR signals. By exploring how different liquid water contents (LWC) and water-inclusions size affect the GPR signal, we show that their effects are much larger than the potential presence of a wet snowpack or a heterogeneous distribution of ice permittivity. In particularly, we show that the presence of such water inclusions is a necessary and sufficient condition for reproducing the typical characteristics of GPR data acquired in the field. Further, we find that for 25 MHz GPR antennas, a bulk LWC $gtrsim$ 0.2%, associated with decimeters-scale water inclusions already limits bedrock detectability for ice thicknesses $gtrsim 100$ m. Since these values are typical for Alpine glaciers, they clarify why the quality of GPR data is often poor in such environments.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136235637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A novel laser melting sampler for discrete, sub-centimeter depth-resolved analyses of stable water isotopes in ice cores 一种新型激光熔化采样器,用于冰芯中稳定水同位素的离散,亚厘米深度分辨分析
3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-19 DOI: 10.1017/jog.2023.52
Yuko Motizuki, Yoichi Nakai, Kazuya Takahashi, Junya Hirose, Yu Vin Sahoo, Masaki Yumoto, Masayuki Maruyama, Michio Sakashita, Kiwamu Kase, Satoshi Wada, Hideaki Motoyama, Yasushige Yano
Abstract We developed a novel laser melting sampler (LMS) for ice cores to measure the stable water isotope ratios (δ 18 O and δD) as temperature proxies at sub-centimeter depth resolutions. In this LMS system, a 2 mm diameter movable evacuation nozzle holds an optical fiber through which a laser beam irradiates the ice core. The movable nozzle intrudes into the ice core, the laser radiation meanwhile melts the ice cylindrically, and the meltwater is pumped away simultaneously through the same nozzle and transferred to a vial for analysis. To avoid isotopic fractionation of the ice through vaporization, the laser power is adjusted to ensure that the temperature of the meltwater is always kept well below its boiling point. A segment of a Dome Fuji shallow ice core (Antarctica), using the LMS, was then demonstrated to have been discretely sampled with a depth resolution as small as 3 mm: subsequent analysis of δ 18 O, δD, and deuterium excess ( d ) was consistent with results obtained by hand segmentation within measurement uncertainties. With system software to control sampling resolution, the LMS will enable us to identify temperature variations that may be detectable only at sub-centimeter resolutions in ice cores.
摘要研制了一种新型的冰芯激光熔化采样器(LMS),用于测量亚厘米深度分辨率下稳定水同位素(δ 18o和δ d)的温度。在这个LMS系统中,一个直径2毫米的可移动疏散喷嘴容纳一根光纤,激光束通过该光纤照射冰芯。移动喷嘴侵入冰芯,激光辐射同时使冰圆柱状融化,融化水通过同一喷嘴同时被抽走并转移到小瓶中进行分析。为了避免冰在蒸发过程中产生同位素分馏,需要调整激光功率,以确保融水的温度始终保持在远低于沸点的水平。随后,使用LMS对Dome Fuji(南极洲)浅层冰芯的一段进行了离散采样,深度分辨率小至3毫米:随后对δ 18o、δ d和氘过量(d)的分析与测量不确定度内手工分割得到的结果一致。通过控制采样分辨率的系统软件,LMS将使我们能够识别只有在冰芯的亚厘米分辨率下才能检测到的温度变化。
{"title":"A novel laser melting sampler for discrete, sub-centimeter depth-resolved analyses of stable water isotopes in ice cores","authors":"Yuko Motizuki, Yoichi Nakai, Kazuya Takahashi, Junya Hirose, Yu Vin Sahoo, Masaki Yumoto, Masayuki Maruyama, Michio Sakashita, Kiwamu Kase, Satoshi Wada, Hideaki Motoyama, Yasushige Yano","doi":"10.1017/jog.2023.52","DOIUrl":"https://doi.org/10.1017/jog.2023.52","url":null,"abstract":"Abstract We developed a novel laser melting sampler (LMS) for ice cores to measure the stable water isotope ratios (δ 18 O and δD) as temperature proxies at sub-centimeter depth resolutions. In this LMS system, a 2 mm diameter movable evacuation nozzle holds an optical fiber through which a laser beam irradiates the ice core. The movable nozzle intrudes into the ice core, the laser radiation meanwhile melts the ice cylindrically, and the meltwater is pumped away simultaneously through the same nozzle and transferred to a vial for analysis. To avoid isotopic fractionation of the ice through vaporization, the laser power is adjusted to ensure that the temperature of the meltwater is always kept well below its boiling point. A segment of a Dome Fuji shallow ice core (Antarctica), using the LMS, was then demonstrated to have been discretely sampled with a depth resolution as small as 3 mm: subsequent analysis of δ 18 O, δD, and deuterium excess ( d ) was consistent with results obtained by hand segmentation within measurement uncertainties. With system software to control sampling resolution, the LMS will enable us to identify temperature variations that may be detectable only at sub-centimeter resolutions in ice cores.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Estimating the elastic modulus of landfast ice from wave observations 由波浪观测估计陆面冰的弹性模量
IF 3.4 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-06 DOI: 10.1017/jog.2023.63
J. Voermans, J. Rabault, A. Marchenko, T. Nose, T. Waseda, A. Babanin
Progress in our understanding of wave–ice interactions is currently hindered by the lack of in situ observations and information of sea-ice properties, including the elastic modulus. Here, we estimate the effective elastic modulus of sea ice using observations of waves in ice through the deployment of three open-source geophone recorders on landfast sea ice. From observations of low-frequency dispersive waves, we obtain an estimate of the effective elastic modulus in the range of 0.4–0.7 GPa. This is lower than the purely elastic modulus of the ice estimated at 1 GPa as derived from in situ beam experiments. Importantly, our experimental observation is significantly lower than the default value currently in use in wave models. While our estimate is not representative for all sea ice, it does indicate that considerably more measurements are required to provide confidence in the development of parameterizations for this complex sea-ice property for wave models.
目前,由于缺乏海冰特性(包括弹性模量)的现场观测和信息,我们对波浪-冰相互作用的理解进展受到阻碍。在这里,我们通过在登陆海冰上部署三个开源地震检波器记录器,利用冰中波浪的观测来估计海冰的有效弹性模量。根据低频色散波的观测,我们获得了0.4–0.7 GPa范围内的有效弹性模量的估计值。这低于根据现场梁实验估计的1GPa的冰的纯弹性模量。重要的是,我们的实验观测值明显低于目前波浪模型中使用的默认值。虽然我们的估计并不代表所有海冰,但它确实表明,需要更多的测量来为波浪模型的这种复杂海冰特性的参数化发展提供信心。
{"title":"Estimating the elastic modulus of landfast ice from wave observations","authors":"J. Voermans, J. Rabault, A. Marchenko, T. Nose, T. Waseda, A. Babanin","doi":"10.1017/jog.2023.63","DOIUrl":"https://doi.org/10.1017/jog.2023.63","url":null,"abstract":"\u0000 Progress in our understanding of wave–ice interactions is currently hindered by the lack of in situ observations and information of sea-ice properties, including the elastic modulus. Here, we estimate the effective elastic modulus of sea ice using observations of waves in ice through the deployment of three open-source geophone recorders on landfast sea ice. From observations of low-frequency dispersive waves, we obtain an estimate of the effective elastic modulus in the range of 0.4–0.7 GPa. This is lower than the purely elastic modulus of the ice estimated at 1 GPa as derived from in situ beam experiments. Importantly, our experimental observation is significantly lower than the default value currently in use in wave models. While our estimate is not representative for all sea ice, it does indicate that considerably more measurements are required to provide confidence in the development of parameterizations for this complex sea-ice property for wave models.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46365000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Quantified mass loss of the Laohugou ice core and its precipitation signal during 1961–2005 at high elevation in the northeastern Tibetan Plateau 青藏高原东北部高海拔老虎沟冰芯1961-2005年量化质量损失及其降水信号
IF 3.4 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-06 DOI: 10.1017/jog.2023.51
W. Du, Shichang Kang, Ji-zu Chen, Weijun Sun, Xiang Qin, Zhenming Ji, Wenxuan Sun, Yanan Qiu
Ice records provide a qualitative rather than a quantitative indication of the trend of climate change. Using the bulk aerodynamic method and degree day model, this study quantified ice mass loss attributable to sublimation/evaporation (S/E) and meltwater on the basis of integrated observations (1960–2006) of glacier-related and atmospheric variables in the northeastern Tibetan Plateau. During 1961–2005, the average annual mass loss in the ice core was 95.33 ± 20.56 mm w.e. (minimum: 78.97 mm w.e. in 1967, maximum: 146.67 mm w.e. in 2001), while the average ratio of the revised annual ice accumulation was 21.2 ± 7.7% (minimum: 11.0% in 1992, maximum 44.8% in 2000). A quantitative formula expressing the relationship between S/E and air temperature at the monthly scale was established, which could be extended to estimation of S/E changes of other glaciers in other regions. The elevation effect on alpine precipitation determined using revised ice accumulation and instrumental data was found remarkable. This work established a method for quantitative assessment of the temporal variation in ice core mass loss, and advanced the reconstruction of long-term precipitation at high elevations. Importantly, the formula established for reconstruction of S/E from temperature time series data could be used in other regions.
冰记录提供了气候变化趋势的定性而非定量指示。本研究采用整体空气动力学方法和度日模型,在对青藏高原东北部冰川相关和大气变量的综合观测(1960-2006)的基础上,量化了升华/蒸发(S/E)和融水造成的冰质量损失。1961年至2005年间,冰芯的平均年质量损失为95.33±20.56毫米(1967年最小:78.97毫米,2001年最大:146.67毫米),而修正后的年积冰平均比例为21.2±7.7%(1992年最小:11.0%,2000年最大:44.8%)。建立了一个表示月尺度S/E与气温关系的定量公式,该公式可推广到其他地区其他冰川S/E变化的估计。使用修正的冰积累和仪器数据确定的海拔对高山降水的影响是显著的。这项工作建立了一种定量评估冰芯质量损失时间变化的方法,并提出了高海拔地区长期降水的重建方法。重要的是,根据温度-时间序列数据建立的S/E重建公式可以用于其他区域。
{"title":"Quantified mass loss of the Laohugou ice core and its precipitation signal during 1961–2005 at high elevation in the northeastern Tibetan Plateau","authors":"W. Du, Shichang Kang, Ji-zu Chen, Weijun Sun, Xiang Qin, Zhenming Ji, Wenxuan Sun, Yanan Qiu","doi":"10.1017/jog.2023.51","DOIUrl":"https://doi.org/10.1017/jog.2023.51","url":null,"abstract":"\u0000 Ice records provide a qualitative rather than a quantitative indication of the trend of climate change. Using the bulk aerodynamic method and degree day model, this study quantified ice mass loss attributable to sublimation/evaporation (S/E) and meltwater on the basis of integrated observations (1960–2006) of glacier-related and atmospheric variables in the northeastern Tibetan Plateau. During 1961–2005, the average annual mass loss in the ice core was 95.33 ± 20.56 mm w.e. (minimum: 78.97 mm w.e. in 1967, maximum: 146.67 mm w.e. in 2001), while the average ratio of the revised annual ice accumulation was 21.2 ± 7.7% (minimum: 11.0% in 1992, maximum 44.8% in 2000). A quantitative formula expressing the relationship between S/E and air temperature at the monthly scale was established, which could be extended to estimation of S/E changes of other glaciers in other regions. The elevation effect on alpine precipitation determined using revised ice accumulation and instrumental data was found remarkable. This work established a method for quantitative assessment of the temporal variation in ice core mass loss, and advanced the reconstruction of long-term precipitation at high elevations. Importantly, the formula established for reconstruction of S/E from temperature time series data could be used in other regions.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43247250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Detection and characterization of discontinuous motion on Thompson Glacier, Canadian High Arctic, using synthetic aperture radar speckle tracking and ice-flow modeling 利用合成孔径雷达散斑跟踪和冰流建模探测和表征加拿大北极高地汤普森冰川的不连续运动
IF 3.4 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2023-09-06 DOI: 10.1017/jog.2023.67
Giovanni Corti, B. Rabus, G. Flowers
We investigate unusual discontinuous glacier motion on Thompson Glacier, Umingmat Nunaat, Arctic Canada, using synthetic aperture radar (SAR) images and ice-flow modeling. A novel intensity-rescaling scheme is developed to reduce errors in high-resolution speckle tracking, resulting in a ~25% improvement in accuracy. Interferometric SAR (InSAR) and speckle tracking using high resolution RADARSAT-2 data indicate velocity discontinuities of up to 1 cm d−1 across deep and longitudinally extensive supraglacial channels on Thompson Glacier. We use a cross-sectional finite-element ice-flow model to determine the conditions under which velocity discontinuities of the observed magnitude and signature are possible. The modeling suggests that discontinuous motion across (long and straight) supraglacial channels can occur without ice fracture and under a wide variety of glacier thermal structures, including in fully temperate glaciers. Despite the wide range of conditions conducive to discontinuous motion, the form we observe requires that the associated channels be deep, longitudinally extensive and located in regions of lateral shearing. We speculate that these combined conditions are rare except on polythermal glaciers, where drainage features such as moulins are comparatively scarce and lower deformation rates allow channels to incise consistently and persist over many years.
我们使用合成孔径雷达(SAR)图像和冰流建模,研究了加拿大北极乌明马特-努纳特汤普森冰川上不寻常的不连续冰川运动。开发了一种新的强度重新缩放方案,以减少高分辨率散斑跟踪中的误差,从而使精度提高约25%。干涉SAR(InSAR)和使用高分辨率RADARSAT-2数据的散斑跟踪表明,汤普森冰川上深层和纵向扩展的冰上通道的速度不连续性高达1 cm d−1。我们使用截面有限元冰流模型来确定观测到的幅度和特征的速度不连续性可能存在的条件。该模型表明,在没有冰破裂的情况下,在各种各样的冰川热结构下,包括在全温带冰川中,可以发生跨越(长而直)冰上通道的不连续运动。尽管有利于不连续运动的广泛条件,但我们观察到的形式要求相关通道是深的、纵向延伸的,并且位于横向剪切区域。我们推测,除了多热冰川外,这些综合条件很少见,多热冰川的排水特征(如丘林)相对较少,较低的变形率使通道能够持续切割并持续多年。
{"title":"Detection and characterization of discontinuous motion on Thompson Glacier, Canadian High Arctic, using synthetic aperture radar speckle tracking and ice-flow modeling","authors":"Giovanni Corti, B. Rabus, G. Flowers","doi":"10.1017/jog.2023.67","DOIUrl":"https://doi.org/10.1017/jog.2023.67","url":null,"abstract":"\u0000 We investigate unusual discontinuous glacier motion on Thompson Glacier, Umingmat Nunaat, Arctic Canada, using synthetic aperture radar (SAR) images and ice-flow modeling. A novel intensity-rescaling scheme is developed to reduce errors in high-resolution speckle tracking, resulting in a ~25% improvement in accuracy. Interferometric SAR (InSAR) and speckle tracking using high resolution RADARSAT-2 data indicate velocity discontinuities of up to 1 cm d−1 across deep and longitudinally extensive supraglacial channels on Thompson Glacier. We use a cross-sectional finite-element ice-flow model to determine the conditions under which velocity discontinuities of the observed magnitude and signature are possible. The modeling suggests that discontinuous motion across (long and straight) supraglacial channels can occur without ice fracture and under a wide variety of glacier thermal structures, including in fully temperate glaciers. Despite the wide range of conditions conducive to discontinuous motion, the form we observe requires that the associated channels be deep, longitudinally extensive and located in regions of lateral shearing. We speculate that these combined conditions are rare except on polythermal glaciers, where drainage features such as moulins are comparatively scarce and lower deformation rates allow channels to incise consistently and persist over many years.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49181057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
期刊
Journal of Glaciology
全部 Acc. Chem. Res. ACS Applied Bio Materials ACS Appl. Electron. Mater. ACS Appl. Energy Mater. ACS Appl. Mater. Interfaces ACS Appl. Nano Mater. ACS Appl. Polym. Mater. ACS BIOMATER-SCI ENG ACS Catal. ACS Cent. Sci. ACS Chem. Biol. ACS Chemical Health & Safety ACS Chem. Neurosci. ACS Comb. Sci. ACS Earth Space Chem. ACS Energy Lett. ACS Infect. Dis. ACS Macro Lett. ACS Mater. Lett. ACS Med. Chem. Lett. ACS Nano ACS Omega ACS Photonics ACS Sens. ACS Sustainable Chem. Eng. ACS Synth. Biol. Anal. Chem. BIOCHEMISTRY-US Bioconjugate Chem. BIOMACROMOLECULES Chem. Res. Toxicol. Chem. Rev. Chem. Mater. CRYST GROWTH DES ENERG FUEL Environ. Sci. Technol. Environ. Sci. Technol. Lett. Eur. J. Inorg. Chem. IND ENG CHEM RES Inorg. Chem. J. Agric. Food. Chem. J. Chem. Eng. Data J. Chem. Educ. J. Chem. Inf. Model. J. Chem. Theory Comput. J. Med. Chem. J. Nat. Prod. J PROTEOME RES J. Am. Chem. Soc. LANGMUIR MACROMOLECULES Mol. Pharmaceutics Nano Lett. Org. Lett. ORG PROCESS RES DEV ORGANOMETALLICS J. Org. Chem. J. Phys. Chem. J. Phys. Chem. A J. Phys. Chem. B J. Phys. Chem. C J. Phys. Chem. Lett. Analyst Anal. Methods Biomater. Sci. Catal. Sci. Technol. Chem. Commun. Chem. Soc. Rev. CHEM EDUC RES PRACT CRYSTENGCOMM Dalton Trans. Energy Environ. Sci. ENVIRON SCI-NANO ENVIRON SCI-PROC IMP ENVIRON SCI-WAT RES Faraday Discuss. Food Funct. Green Chem. Inorg. Chem. Front. Integr. Biol. J. Anal. At. Spectrom. J. Mater. Chem. A J. Mater. Chem. B J. Mater. Chem. C Lab Chip Mater. Chem. Front. Mater. Horiz. MEDCHEMCOMM Metallomics Mol. Biosyst. Mol. Syst. Des. Eng. Nanoscale Nanoscale Horiz. Nat. Prod. Rep. New J. Chem. Org. Biomol. Chem. Org. Chem. Front. PHOTOCH PHOTOBIO SCI PCCP Polym. Chem.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1