Journal of Glaciology最新文献_第2页

Observed meltwater-induced flexure and fracture at a doline on George VI Ice Shelf, Antarctica 在南极洲乔治六世冰架上观察到的融水引起的挠曲和断裂

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2024-05-03 DOI: 10.1017/jog.2024.31

Alison F. Banwell, Ian C. Willis, Laura A. Stevens, Rebecca L. Dell, Douglas R. MacAyeal

{"title":"Observed meltwater-induced flexure and fracture at a doline on George VI Ice Shelf, Antarctica","authors":"Alison F. Banwell, Ian C. Willis, Laura A. Stevens, Rebecca L. Dell, Douglas R. MacAyeal","doi":"10.1017/jog.2024.31","DOIUrl":"https://doi.org/10.1017/jog.2024.31","url":null,"abstract":"Global Navigation Satellite System (GNSS) observations and ground-based timelapse photography obtained over the record-high 2019/2020 melt season are combined to characterise the flexure and fracture behaviour of a previously formed doline on George VI Ice Shelf, Antarctica. The GNSS timeseries shows a downward vertical displacement of the doline centre with respect to the doline rim of ~60 cm in response to loading from a central meltwater lake. The GNSS data also show a tens-of-days episode of rapid-onset, exponentially decaying horizontal displacement, where the horizontal distance between the doline rim and its centre increases by ~70 cm. We interpret this event as the initiation and/or widening of a fracture, aided by stress perturbations associated with meltwater loading in the doline basin. Viscous flexure modelling indicates that the meltwater loading generates tensile surface stresses exceeding 75 kPa. This, together with our timelapse photos of circular fractures around the doline, suggests the first such documentation of meltwater-loading-induced ‘ring fracture’ formation on an ice shelf, equivalent to the fracture type proposed as part of the chain-reaction lake drainage process involved in the 2002 breakup of the Larsen B Ice Shelf.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835293","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

Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland 瑞士 Grosser Aletschgletscher 航天雷达信号穿透造成的高程偏差

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2024-04-30 DOI: 10.1017/jog.2024.37

Jacqueline Bannwart, Livia Piermattei, Inés Dussaillant, Lukas Krieger, Dana Floricioiu, Etienne Berthier, Claudia Roeoesli, Horst Machguth, Michael Zemp

{"title":"Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland","authors":"Jacqueline Bannwart, Livia Piermattei, Inés Dussaillant, Lukas Krieger, Dana Floricioiu, Etienne Berthier, Claudia Roeoesli, Horst Machguth, Michael Zemp","doi":"10.1017/jog.2024.37","DOIUrl":"https://doi.org/10.1017/jog.2024.37","url":null,"abstract":"<p>Digital elevation models (DEMs) from the spaceborne interferometric radar mission TanDEM-X hold a large potential for glacier change assessments. However, a bias is potentially introduced through the penetration of the X-band signal into snow and firn. To improve our understanding of radar penetration on glaciers, we compare DEMs derived from the almost synchronous acquisition of TanDEM-X and Pléiades optical stereo-images of Grosser Aletschgletscher in March 2021. We found that the elevation bias – averaged per elevation bin – can reach up to 4–8 m in the accumulation area, depending on post co-registration corrections. Concurrent in situ measurements (ground-penetrating radar, snow cores, snow pits) reveal that the signal is not obstructed by the last summer horizon but reaches into perennial firn. Because of volume scattering, the TanDEM-X surface is determined by the scattering phase centre and does not coincide with a specific firn layer. We show that the bias corresponds to more than half of the decadal ice loss rate. To minimize the radar penetration bias, we recommend to select DEMs from the same time of the year and over long observation periods. A correction of the radar penetration bias is recommended, especially when combining optical and TanDEM-X DEMs.</p>","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196967","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

Improved processing methods for eddy covariance measurements in calculating sensible heat fluxes at glacier surfaces 在计算冰川表面显热通量时改进涡度协方差测量的处理方法

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2024-04-30 DOI: 10.1017/jog.2024.39

Cole Lord-May, Valentina Radić

{"title":"Improved processing methods for eddy covariance measurements in calculating sensible heat fluxes at glacier surfaces","authors":"Cole Lord-May, Valentina Radić","doi":"10.1017/jog.2024.39","DOIUrl":"https://doi.org/10.1017/jog.2024.39","url":null,"abstract":"<p>Bulk aerodynamic methods have been shown to perform poorly in computing turbulent heat fluxes at glacier surfaces during shallow katabatic winds. Katabatic surface layers have different wind shear and flux profiles to the surface layers for which the bulk methods were developed, potentially invalidating their use in these conditions. In addition, eddy covariance-derived turbulent heat fluxes are unlikely to be representative of surface conditions when eddy covariance data are collected close to the wind speed maximum (WSM). Here we utilize two months of eddy covariance and meteorological data measured at three different heights (1 m, 2 m, and 3 m) at Kaskawulsh Glacier in the Yukon, Canada, to re-examine the performance of bulk methods relative to eddy covariance-derived fluxes under different near-surface flow regimes. We propose a new set of processing methods for one-level eddy covariance data to ensure the validity of calculated fluxes during highly variable flows and low-level wind speed maxima, which leads to improved agreement between eddy covariance-derived and modelled fluxes across all flow regimes, with the best agreement (correlation >0.9) 1 m above the surface. Contrary to previous studies, these results show that adequately processed eddy covariance data collected at or above the WSM can provide valid estimates of surface heat fluxes.</p>","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141197160","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

Short-term calving front dynamics and mass loss at Sálajiegna glacier, northern Sweden, assessed by uncrewed surface and aerial vehicles 瑞典北部 Sálajiegna 冰川的短期崩塌前沿动态和质量损失，由无人驾驶的地面和空中飞行器进行评估

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2024-04-24 DOI: 10.1017/jog.2024.34

Florian Vacek, Clemens Deutsch, Jakob Kuttenkeuler, Nina Kirchner

引用次数: 0

Potential threats of glacial lake changes to the Sichuan-Tibet Railway 冰湖变化对川藏公路的潜在威胁

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2024-04-22 DOI: 10.1017/jog.2024.40

Menger Peng, Guoqing Zhang, Jinyuan Yu, Weicai Wang, Fenglin Xu, Sonam Rinzin

引用次数: 0

Transient subglacial water routing efficiency modulates ice velocities prior to surge termination on Sít’ Kusá, AK 瞬态冰川下水路由效率调节阿拉斯加州 Sít' Kusá 浪涌终止前的冰速