scholarly journals Changes in glacier dynamics at the northern Antarctic Peninsula since 1985

2017 ◽  
Author(s):  
Thorsten Seehaus ◽  
Alison Cook ◽  
Aline B. Silva ◽  
Matthias H. Braun
Keyword(s):  
Antarctic Peninsula ◽  
East Coast ◽  
Temporal Trends ◽  
Climatic Conditions ◽  
Surface Velocity ◽  
Glacier Area ◽  
Ice Dynamics ◽  
Ice Shelves ◽  
Ice Surface ◽  
Glacier Dynamics

Abstract. The climatic conditions along the northern Antarctic Peninsula have shown significant changes within the last 50 years. Most studies have focused on the glaciers affected by the disintegration of the ice shelves along the east coast. However, temporally and spatially detailed observations of the changes in ice dynamics along both the east and west coastlines are missing. Temporal trends of glacier area (1985–2015) and ice surface velocity (1992–2014) changes are derived from a broad multi-mission remote sensing database for 74 glacier basins on the northern Antarctic Peninsula (

scholarly journals Changes in glacier dynamics in the northern Antarctic Peninsula since 1985

2018 ◽  
Vol 12 (2) ◽  
pp. 577-594 ◽  
Author(s):  
Thorsten Seehaus ◽  
Alison J. Cook ◽  
Aline B. Silva ◽  
Matthias Braun
Keyword(s):  
Antarctic Peninsula ◽  
West Coast ◽  
East Coast ◽  
Hierarchical Cluster ◽  
Flow Speed ◽  
Climatic Conditions ◽  
Surface Velocity ◽  
Ice Shelf ◽  
The West ◽  
Ice Dynamics

Abstract. The climatic conditions along the northern Antarctic Peninsula have shown significant changes within the last 50 years. Here we present a comprehensive analysis of temporally and spatially detailed observations of the changes in ice dynamics along both the east and west coastlines of the northern Antarctic Peninsula. Temporal evolutions of glacier area (1985–2015) and ice surface velocity (1992–2014) are derived from a broad multi-mission remote sensing database for 74 glacier basins on the northern Antarctic Peninsula ( <  65° S along the west coast and north of the Seal Nunataks on the east coast). A recession of the glaciers by 238.81 km2 is found for the period 1985–2015, of which the glaciers affected by ice shelf disintegration showed the largest retreat by 208.59 km2. Glaciers on the east coast north of the former Prince Gustav Ice Shelf extent in 1986 receded by only 21.07 km2 (1985–2015) and decelerated by about 58 % on average (1992–2014). A dramatic acceleration after ice shelf disintegration with a subsequent deceleration is observed at most former ice shelf tributaries on the east coast, combined with a significant frontal retreat. In 2014, the flow speed of the former ice shelf tributaries was 26 % higher than before 1996. Along the west coast the average flow speeds of the glaciers increased by 41 %. However, the glaciers on the western Antarctic Peninsula revealed a strong spatial variability of the changes in ice dynamics. By applying a hierarchical cluster analysis, we show that this is associated with the geometric parameters of the individual glacier basins (hypsometric indexes, maximum surface elevation of the basin, flux gate to catchment size ratio). The heterogeneous spatial pattern of ice dynamic evolutions at the northern Antarctic Peninsula shows that temporally and spatially detailed observations as well as further monitoring are necessary to fully understand glacier change in regions with such strong topographic and climatic variances.

scholarly journals Climatic conditions, mass balance and dynamics of Larsen B ice shelf, Antarctic Peninsula, prior to collapse

2004 ◽  
Vol 39 ◽  
pp. 557-562 ◽  
Author(s):  
Pedro Skvarca ◽  
Hernán De Angelis ◽  
Andrés F. Zakrajsek
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Satellite Image ◽  
Climatic Conditions ◽  
Strain Rates ◽  
Ice Shelf ◽  
Ice Flow ◽  
Ice Shelves ◽  
Additional Information ◽  
Significant Acceleration

AbstractFollowing the collapse of Larsen A in 1995, about 3200 km2 of Larsen B ice shelf disintegrated in early 2002 during the warmest summer recorded on the northeastern Antarctic Peninsula. Immediately prior to disintegration the last field campaign was carried out on Larsen B. Measurements included surface net mass balance, velocity and strain rate on a longitudinal transect along Crane Glacier flowline and over a remnant section confined within Seal Nunataks that survived the collapse. In addition, an automatic weather station located nearby allowed derivation of melt days relevant to the formation and extent of surface meltwater. Repeated surveys allowed us to detect a significant acceleration in ice-flow velocity and associated increasing strain rates along the longitudinal transect. It may be possible to use this acceleration as a predictor of imminent ice-shelf collapse, applicable to ice shelves subject to similar climatic conditions. Additional information on recent ongoing changes was provided by a visible satellite image acquired in early 2003.

scholarly journals Present dynamics and future prognosis of a slowly surging glacier

2011 ◽  
Vol 5 (1) ◽  
pp. 299-313 ◽  
Author(s):  
G. E. Flowers ◽  
N. Roux ◽  
S. Pimentel ◽  
C. G. Schoof
Keyword(s):  
Mass Balance ◽  
Force Balance ◽  
Surface Velocity ◽  
Internal Dynamic ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Surface ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Negative Balance

Abstract. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2) valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

Supraglacial Streams and Rivers

2019 ◽  
Vol 47 (1) ◽  
pp. 421-452 ◽  
Author(s):  
Lincoln H Pitcher ◽  
Laurence C. Smith
Keyword(s):  
Sea Level ◽  
Transport Processes ◽  
Future Research ◽  
Sea Level Changes ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Shelves ◽  
Streams And Rivers ◽  
Ice Surface ◽  
Global Sea Level

Supraglacial meltwater channels that flow on the surfaces of glaciers, ice sheets, and ice shelves connect ice surface climatology with subglacial processes, ice dynamics, and eustatic sea level changes. Their important role in transferring water and heat across and into ice is currently absent from models of surface mass balance and runoff contributions to global sea level rise. Furthermore, relatively little is known about the genesis, evolution, hydrology, hydraulics, and morphology of supraglacial rivers, and a first synthesis and review of published research on these unusual features is lacking. To that end, we review their ( a) known geographical distribution; ( b) formation, morphology, and sediment transport processes; ( c) hydrology and hydraulics; and ( d) impact on ice sheet surface energy balance, heat exchange, basal conditions, and ice shelf stability. We conclude with a synthesis of key knowledge gaps and provide recommendations for future research. ▪ Supraglacial streams and rivers transfer water and heat on glaciers, connecting climate with subglacial hydrology, ice sliding, and global sea level. ▪ Ice surface melting may expand under a warming climate, darkening the ice surface and further increasing melt.

scholarly journals Mapping tide-water glacier dynamics in East Greenland using Landsat data

1995 ◽  
Vol 41 (139) ◽  
pp. 584-595 ◽  
Author(s):  
John L. Dwyer
Keyword(s):  
Cross Correlation ◽  
Drainage Basin ◽  
Surface Velocity ◽  
Key Factors ◽  
Remotely Sensed Data ◽  
East Greenland ◽  
Ice Surface ◽  
Glacier Terminus ◽  
Glacier Dynamics ◽  
Continuous Presence

AbstractLandsat multispectral scanner and thematic mapper images were co-registered For the Kangerdlugssuaq Fjord region in East Greenland and were used to map glacier drainage-basin areas, changes in the positions of tide-water glacier termini and to estimate surface velocities of the larger tide-water glaciers. Statistics were compiled to document distance and area changes to glacier termini. The methodologies developed in this study are broadly applicable to the investigation of tide-water glaciers in other areas. The number of images available for consecutive years and the accuracy with which images are co-registered are key factors that influence the degree to which regional glacier dynamics can be characterized using remotely sensed data.Three domains of glacier state were interpreted: net increase in terminus area in the southern part of the study area, net loss of terminus area for glaciers in upper Kangerdlugssuaq Fjord and a slight loss of glacier terminus area northward from Ryberg Fjord. Local increases in the concentrations of drifting icebergs in the fjords coincide with the observed extension of glacier termini positions Ice-surface velocity estimates were derived for several glaciers using automated image cross-correlation techniques The velocity determined for Kangerdlugssuaq Gletscher is approximately 5.0 km a−1and that for Kong Christian IV Gletscher is 0.9 km a−1. The continuous presence of icebergs and brash ice in front of these glaciers indicates sustained rates of ice-front calving.

scholarly journals Present dynamics and future prognosis of a slowly surging glacier

2010 ◽  
Vol 4 (4) ◽  
pp. 1839-1876
Author(s):  
G. E. Flowers ◽  
N. Roux ◽  
S. Pimentel
Keyword(s):  
Mass Balance ◽  
Surface Profile ◽  
Yukon Territory ◽  
Force Balance ◽  
Surface Velocity ◽  
Internal Dynamic ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Surface ◽  
Glacier Flow

Abstract. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (e.g. period, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (~5 km2) valley glacier in the Yukon Territory of Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when high basal water pressures (55–90% of flotation) are prescribed over the central region of the glacier, consistent with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a large bedrock bump beneath the current equilibrium line of the glacier. This bump provides resistance to ice flow sufficient to cause the formation of a bulge in the ice-surface profile. We suggest that the bedrock bump contributes to the propensity for surges in this glacier, such that conditions suppressing ice-bulge formation over the bump may also inhibit surges. In our calculations such a situation arises for sufficiently negative values of mass balance. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a "slow surge", and confirm a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

scholarly journals Assessing Controls on Ice Dynamics at Crane Glacier, Antarctic Peninsula Using a Numerical Ice Flow Model

2021 ◽  
Author(s):  
Rainey Aberle
Keyword(s):  
Antarctic Peninsula ◽  
Flow Model ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Ice Flow ◽  
Surface Mass ◽  
Climate Conditions ◽  
Ice Shelves ◽  
Tidewater Glacier ◽  
Mass Discharge

The widespread retreat of glaciers and the collapse of ice shelves along the Antarctic Peninsula has been attributed to atmospheric and oceanic warming, which promotes mass loss. However, several glaciers on the eastern peninsula that were buttressed by the Larsen A and B ice shelves prior to collapse in 1995 and 2002, respectively, have been advancing in recent years. This asymmetric pattern of rapid retreat and long-term re-advance is similar to the tidewater glacier cycle, which can occur largely independent of climate forcing. Here, I use a width- and depth-integrated numerical ice flow model to investigate glacier response to ice shelf collapse and the influence of changing climate conditions at Crane Glacier, formerly a tributary of the Larsen B ice shelf, over the last ~10 years. Sensitivity tests to explore the influence of perturbations in surface mass balance and submarine melt (up to 10 m a-1) and fresh water impounded in crevasses (up to 10 m) on glacier dynamics reveal that by 2100, the modeled mass discharge ranges from 0.53-98 Gt a-1, with the most substantial changes due to surface melt-induced thinning. My findings suggest that the growth of a floating ice tongue can hinder enhanced flow, allowing the grounding zone to remain steady for many decades, analogous to the advancing stage of the tidewater glacier cycle. Additionally, former tributary glaciers can take several decades to geometrically adjust to ice shelf collapse at their terminal boundary while elevated glacier discharge persists.

Velocities of the Amery Ice Shelf's primary tributary glaciers, 2004–12

2015 ◽  
Vol 27 (5) ◽  
pp. 511-523 ◽  
Author(s):  
M.L. Pittard ◽  
J.L. Roberts ◽  
C.S. Watson ◽  
B.K. Galton-Fenzi ◽  
R.C. Warner ◽  
...  
Keyword(s):  
Surface Velocity ◽  
Ice Shelf ◽  
Ice Flow ◽  
Ice Shelves ◽  
Ice Surface ◽  
Amery Ice Shelf ◽  
Landsat 7 ◽  
One Year ◽  
Shelf Region

AbstractMonitoring the rate of ice flow into ice shelves is vital to understanding how, where and when mass changes occur in Antarctica. Previous observations of ice surface velocity indicate that the Amery Ice Shelf and tributary glaciers have been relatively stable over the period 1968 to 1999. This study measured the displacement of features on the ice surface over a sequence of Landsat 7 images separated by approximately one year and spanning 2004 to 2012 using the surface feature tracking software IMCORR. The focus is on the region surrounding the southern grounding zone of the Amery Ice Shelf and its primary tributary glaciers: the Fisher, Lambert and Mellor glaciers. No significant changes in surface velocity were observed over this period. Accordingly, the velocity fields from each image pair between 2004 and 2012 were used to synthesize an average velocity dataset of the Amery Ice Shelf region and to compare it to previously published velocity datasets and in situ global positioning system velocity observations. No significant change in ice surface velocities was found between 2004 and 2012 in the Amery Ice Shelf region, which suggests that it continues to remain stable.

FEM-modelling of ice dynamics without remeshing

2020 ◽  
Author(s):  
Josefin Ahlkrona ◽  
Daniel Elfverson
Keyword(s):  
Stokes Equations ◽  
Partial Slip ◽  
The Finite Element Method ◽  
Ice Dynamics ◽  
Ice Shelves ◽  
Ice Surface ◽  
Level Set Function ◽  
Irregular Geometries ◽  
Structured Meshes ◽  
Set Function

&lt;p&gt;&lt;span&gt;The Finite Element Method (FEM) has become a popular method for numerical ice sheet modelling, partly due to its capability of representing complex geometries. However, there is a limit to just how complicated these geometries can be. In the presence of irregular geometries and moving boundaries like those appearing in glaciology, costly remeshing and low mesh quality may become issues. To overcome these problems, new unfitted sharp interface methods such as CutFEM are being developed by the FEM community. The CutFEM method allows for the boundary to cut through a mesh, without requiring the element nodes to be located on the boundary. In this way simple structured meshes can be used and remeshing is avoided while accuracy and stability is retained. We develop a CutFEM method for the full Stokes equations and apply it to a transient simulation of the Arolla Glacier with both no slip and partial slip conditions at the bed, using a level-set function to track the moving ice surface. We demonstrate accuracy of the method and discuss extensions to modelling ice shelves and moving grounding lines.&lt;/span&gt;&lt;/p&gt;

scholarly journals Oceanic Environment of George VI Ice Shelf, Antarctic Peninsula

1988 ◽  
Vol 11 ◽  
pp. 161-164 ◽  
Author(s):  
M. H. Talbot
Keyword(s):  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Sea Water ◽  
Freezing Point ◽  
Climatic Conditions ◽  
Warm Water ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Water Characteristics ◽  
The Antarctic

A collation of available data shows that sea-water with a temperature 3°C above the in-situ freezing point lies beneath George VI Ice Shelf in the Antarctic Peninsula, and is widespread on the Amundsen-Bellingshausen continental shelf. The presence of warm water is a factor in the recent and continuing disintegration of ice shelves in the region, yet the meteorology and oceanography of the sector are little known. We discuss a plausible link between the present climatic conditions, sea-water characteristics and the warm-water intrusion on to the continental shelf, thereby illustrating an indirect climatic influence on the mass balance of ice shelves.

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