Journal of Glaciology最新文献_第8页

A comparison of contemporaneous airborne altimetry and ice-thickness measurements of Antarctic ice shelves 南极冰架同时期空中测高和冰厚测量的比较

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-08-03 DOI: 10.1017/jog.2023.49

Allison M. Chartrand, I. Howat

{"title":"A comparison of contemporaneous airborne altimetry and ice-thickness measurements of Antarctic ice shelves","authors":"Allison M. Chartrand, I. Howat","doi":"10.1017/jog.2023.49","DOIUrl":"https://doi.org/10.1017/jog.2023.49","url":null,"abstract":"\u0000 Estimates of ice shelf mass loss are typically based on surface height measurements, assuming hydrostatic equilibrium and estimated firn thickness. Recent investigations, however, challenge the assumption that ice shelves are freely floating, particularly in proximity to narrow structures such as basal channels and shear margins. We compare contemporaneous measurements of Antarctic ice shelf thickness, from ice-penetrating radar, to freeboard height, from laser altimetry, acquired during multiple airborne surveys. On average, the hydrostatic thickness differs from observed thickness by at least ~17 ± 98 m, but this difference varies well beyond the propagated error within and among ice shelves, and depends on the corrections applied. We find that uncertainty in firn thickness can account for most, but not all, of the imbalance. Overall, errors in hydrostatic thickness do not significantly impact estimated basal melt rates. Our results indicate that localized approaches to estimating ice shelf thickness and rates of change are not applicable at large scales, and vice versa, and point to the need for more abundant and accurate firn and ice thickness measurements to improve estimates and predictions of ice shelf mass loss.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43532270","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 perturbation analysis: a method to estimate ice-sheet bed topography and conditions from surface datasets 冰流摄动分析:一种从地表数据集估计冰盖床地形和条件的方法

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-08-03 DOI: 10.1017/jog.2023.50

Helen Ockenden, R. Bingham, Andrew Curtis, D. Goldberg

{"title":"Ice-flow perturbation analysis: a method to estimate ice-sheet bed topography and conditions from surface datasets","authors":"Helen Ockenden, R. Bingham, Andrew Curtis, D. Goldberg","doi":"10.1017/jog.2023.50","DOIUrl":"https://doi.org/10.1017/jog.2023.50","url":null,"abstract":"\u0000 One of the largest contributors to uncertainty in predictions of sea-level rise from ice-sheet models is a lack of knowledge about the bed topography beneath ice sheets. Bed topography maps are normally made by interpolating between linear radar surveys using methods that include kriging, mass conservation and flowline diffusion, all of which may miss influential mesoscale (2–30 km) bedforms. Previous works have explored an Ice-Flow Perturbation Analysis (IFPA) approach for estimating bed topography using the surface expression of these mesoscale bedforms. Using regions of Pine Island Glacier that have been intensively surveyed by ice-penetrating radar as test sites, and a refined IFPA methodology, we find that IFPA detects bedforms capable of influencing ice flow which are not represented in Bedmachine Antarctica and other interpolated bed products. We further explore the ability of IFPA to estimate relative bed slipperiness, finding higher slipperiness in the main trunk and tributaries. Alongside other methods which estimate ice thickness, bed topography maps from IFPA have the potential to constrain projections of future sea-level rise, especially where radar data are sparse.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41526673","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

JOG volume 69 issue 276 Cover and Back matter JOG卷69期276封面和封底

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-28 DOI: 10.1017/jog.2023.56

引用次数: 0

JOG volume 69 issue 276 Cover and Front matter JOG第69卷第276期封面和封面

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-28 DOI: 10.1017/jog.2023.55

Lecture Theatre

引用次数: 1

Numerical modelling of dense snow avalanches with a well-balanced scheme based on the 2D shallow water equations 基于二维浅水方程的良好平衡方案的密集雪崩数值模拟

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-25 DOI: 10.1017/jog.2023.48

M. Sanz-Ramos, E. Bladé, P. Oller, G. Furdada

引用次数: 2

A shallow approximation for ice streams sliding over strong beds 冰流在坚固床上滑动的浅层近似

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-25 DOI: 10.1017/jog.2023.47

K. Warburton, D. Hewitt, C. Meyer, J. Neufeld

引用次数: 0

Changes in glacier albedo and the driving factors in the Western Nyainqentanglha Mountains from 2001 to 2020 2001年至2020年尼安春坦古拉山脉西部冰川反照率变化及其驱动因素

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-18 DOI: 10.1017/jog.2023.45

Shaoting Ren, L. Jia, M. Menenti, Jing Zhang

{"title":"Changes in glacier albedo and the driving factors in the Western Nyainqentanglha Mountains from 2001 to 2020","authors":"Shaoting Ren, L. Jia, M. Menenti, Jing Zhang","doi":"10.1017/jog.2023.45","DOIUrl":"https://doi.org/10.1017/jog.2023.45","url":null,"abstract":"Abstract Glacier surface albedo dominates glacier energy balance, thus strongly affecting the glacier mass balance. Glaciers in the Western Nyainqentanglha Mountains (WNM) experienced large mass losses in the past two decades, but long-term changes of glacier albedo and its drivers are less understood. In this study, we retrieved glacier albedo with MODIS reflectance data to characterize the spatiotemporal variability of albedo from 2001 to 2020. Air temperature, rainfall, snowfall and deposition of light-absorbing impurities (LAIs) were evaluated as potential drivers of the observed variability in glacier albedo. The results showed that: (1) the glacier albedo experienced large inter-annual fluctuations, with the mean albedo being 0.552 ± 0.002 and a clear decreasing trend of 0.0443 ± 2 × 10−4 dec−1 in the WNM. The fastest decline was observed in autumn and in the vicinity of the equilibrium line altitude, indicating an extended melt season and an expansion of the ablation region to higher elevation; (2) local meteorology and LAIs deposition are the main drivers of glacier albedo change, but their effects on seasonal albedos are different due to different glacier processes. Both air temperature and the balance between liquid and solid precipitation affect summer and autumn albedos due to glacier ablation. Air temperature is the main driver of spring and winter albedos due to sublimation and metamorphism of snow, while snowfall carried by westerlies has limited influence on these two seasonal albedos due to less snowfall. LAIs mainly affect spring albedo due to high concentration coupled with the southerly wind in spring. These findings highlight the significance of changes in glacier albedo and the key role of local meteorology and LAIs deposition in determining such changes, which play an important role in glaciological and cryosphere processes.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48144694","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

Future projections for the Antarctic ice sheet until the year 2300 with a climate-index method 用气候指数法对南极冰盖到2300年的未来预测

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-11 DOI: 10.1017/jog.2023.41

R. Greve, C. Chambers, T. Obase, F. Saito, W. Chan, A. Abe‐Ouchi

{"title":"Future projections for the Antarctic ice sheet until the year 2300 with a climate-index method","authors":"R. Greve, C. Chambers, T. Obase, F. Saito, W. Chan, A. Abe‐Ouchi","doi":"10.1017/jog.2023.41","DOIUrl":"https://doi.org/10.1017/jog.2023.41","url":null,"abstract":"\u0000 As part of the Coupled Model Intercomparison Project Phase 6 (CMIP6), the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) was devised to assess the likely sea-level-rise contribution from the Earth's ice sheets. Here, we construct an ensemble of climate forcings for Antarctica until the year 2300 based on original ISMIP6 forcings until 2100, combined with climate indices from simulations with the MIROC4m climate model until 2300. We then use these forcings to run simulations for the Antarctic ice sheet with the SICOPOLIS model. For the unabated warming pathway RCP8.5/SSP5-8.5, the ice sheet suffers a severe mass loss, amounting to ~ 1.5 m SLE (sea-level equivalent) for the fourteen-experiment mean, and ~ 3.3 m SLE for the most sensitive experiment. Most of this loss originates from West Antarctica. For the reduced emissions pathway RCP2.6/SSP1-2.6, the loss is limited to a three-experiment mean of ~ 0.16 m SLE. The means are approximately two times larger than what was found in a previous study (Chambers and others, 2022, doi:10.1017/jog.2021.124) that assumed a sustained late-21st-century climate beyond 2100, demonstrating the importance of post-2100 climate trends on Antarctic mass changes in the 22nd and 23rd centuries.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47979689","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

Effects of topography on dynamics and mass loss of lake-terminating glaciers in southern Patagonia 地形对巴塔哥尼亚南部湖泊冰川动力学和质量损失的影响

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-11 DOI: 10.1017/jog.2023.42

M. Minowa, Marius Schaefer, P. Skvarca

{"title":"Effects of topography on dynamics and mass loss of lake-terminating glaciers in southern Patagonia","authors":"M. Minowa, Marius Schaefer, P. Skvarca","doi":"10.1017/jog.2023.42","DOIUrl":"https://doi.org/10.1017/jog.2023.42","url":null,"abstract":"\u0000 Calving glaciers are highly sensitive to bedrock geometry near their terminus. To understand the mechanisms controlling rapid calving glaciers’ mass loss, we measured the lake topography in front of four lake-terminating glaciers in the southern Patagonian icefield. Using remotely sensed surface elevation data, we calculated flotation height and surface slope and compared those with changes in ice-front position, surface speed and surface elevation. Rapid retreat accompanied by rapid flow acceleration and ice surface steepening was observed at Glaciar Upsala from 2008–2011, and at O'Higgins and Viedma glaciers from 2016–present. Surface lowering in the lower part of Glaciar Upsala reached 30 m a−1 and was 18 m a−1 and 12 m a−1 at O'Higgins and Viedma glaciers, respectively. Near- or super-buoyant conditions were observed prior to these events, leading to gradual flow acceleration due to low effective pressure and decoupling from the bed. The super-buoyant condition and gradual acceleration imply full-thickness buoyant calving, which causes the ice front to retreat from the shallow bedrock topography with substantial flow acceleration. We conclude that the buoyancy force plays an important role in the rapid mass loss of lake-terminating glaciers in southern Patagonia.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48290401","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

Mass-balance and ablation processes of a perennial polar ice patch on the northern coast of Ellesmere Island 埃尔斯米尔岛北海岸一个常年极地冰盖的质量平衡和消融过程

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-07-11 DOI: 10.1017/jog.2023.44

Gautier Davesne, David H. Fortier, F. Dominé, C. Kinnard

{"title":"Mass-balance and ablation processes of a perennial polar ice patch on the northern coast of Ellesmere Island","authors":"Gautier Davesne, David H. Fortier, F. Dominé, C. Kinnard","doi":"10.1017/jog.2023.44","DOIUrl":"https://doi.org/10.1017/jog.2023.44","url":null,"abstract":"\u0000 Ice patches have implications for landscape and ecosystem dynamics in polar deserts, however, the understanding of the driving factors that control their spatio-temporal variability is limited. This study aims to assess the seasonal and long-term evolution of ice patches on Ward Hunt Island (WHI; 83°N, Canadian High Arctic) based on field measurements of surface mass and energy balance. Results show that mass gains of the ice patch systems occur mostly through drifting snow, making them highly linked to the topography as well as the frequency and magnitude of wind events. Summer ablation is primarily driven by net radiation, but the short-term variability in melt rate is driven by sensible heat fluxes. The highest ablation rates occur during the passage of warm fronts that combine strong winds and mild temperatures. Conversely, foggy days reduce fluxes of solar radiation and sensible heat to the snow/ice surface, thereby suppressing ablation. Ice patches are less climate-sensitive than other cryospheric elements due to a feedback between snow accumulation and topography, however, summer ablation is strongly influenced by micrometeorology. Model projections of these factors suggest that conditions will become critical for preserving ice patches at WHI and along the northern coast of Ellesmere Island as early as in the next decades.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48656005","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