Journal of Glaciology最新文献_第6页

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

Journal of Glaciology Pub Date : 2023-09-26 DOI: 10.1017/jog.2023.70

George Malczyk, Noel Gourmelen, Mauro Werder, Martin Wearing, Dan Goldberg

{"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

Journal of Glaciology Pub Date : 2023-09-26 DOI: 10.1017/jog.2023.73

Guillaume Jouvet, Guillaume Cordonnier

{"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

Journal of Glaciology 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

{"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

Journal of Glaciology Pub Date : 2023-09-21 DOI: 10.1017/jog.2023.71

Alex Huth, Ravindra Duddu, Benjamin Smith, Olga Sergienko

{"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

Journal of Glaciology Pub Date : 2023-09-21 DOI: 10.1017/jog.2023.65

Anna-Mireilla Hayden, Christine F. Dow

{"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

Journal of Glaciology 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

{"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

Journal of Glaciology 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

{"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

Journal of Glaciology Pub Date : 2023-09-06 DOI: 10.1017/jog.2023.63

J. Voermans, J. Rabault, A. Marchenko, T. Nose, T. Waseda, A. Babanin

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

Journal of Glaciology 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

{"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

Journal of Glaciology Pub Date : 2023-09-06 DOI: 10.1017/jog.2023.67

Giovanni Corti, B. Rabus, G. Flowers

{"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