scholarly journals Climatically induced retreat and collapse of northern Larsen Ice Shelf, Antarctic Peninsula

1998 ◽  
Vol 27 ◽  
pp. 86-92 ◽  
Author(s):  
Helmut Rott ◽  
Wolfgang Rack ◽  
Thomas Nagler ◽  
Pedro Skvarca
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
High Sensitivity ◽  
Ice Shelf ◽  
Landsat Images ◽  
Surface Mass ◽  
Ice Shelves ◽  
Radar Images ◽  
Near Future ◽  
Larsen Ice Shelf

The areal changes of the northern Larsen Ite Shelf (LIS), Antarctic Peninsula, between March 1986 and March 1997 have been analyzed, based on synthetic aperture radar images of the European remote-sensing satellites ERS-1 and ERS-2 and on Landsat images. This analysis is complemented by data on ice motion and surface mass balance which have been obtained during several field campaigns since the early 1980s. After a period of retreat, coinciding with atmospheric warming and with decreasing net accumulation at the surface due to melt losses, the two northernmost sections of LIS disintegrated almost completely within a few days in January 1995. Recent observations of the ice-shelf section north of Jason Peninsula, which is presently the northernmost section of LIS, show increased summer melt and intensification of the rifting processes, probably causing accelerated retreat of this section in the near future. The retreat and the disintegration event of LIS indicate high sensitivity of ice shelves to prolonged perturbations of the mass balance.

scholarly journals Changing pattern of ice flow and mass balance for glaciers discharging into the Larsen A and B embayments, Antarctic Peninsula, 2011 to 2016

2017 ◽  
Author(s):  
Helmut Rott ◽  
Wael Abdel Jaber ◽  
Jan Wuite ◽  
Stefan Scheiblauer ◽  
Dana Floricioiu ◽  
...  
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Shelf ◽  
Satellite Mission ◽  
Surface Mass ◽  
Radar Images ◽  
Mass Losses ◽  
Satellite Radar

Abstract. We analyzed volume change and mass balance of outlet glaciers on the northern Antarctic Peninsula over the periods 2011 to 2013 and 2013 to 2016, using high resolution topographic data of the bistatic interferometric radar satellite mission TanDEM-X. Complementary to the geodetic method applying DEM differencing, we computed the net mass balance of the main outlet glaciers by the input/output method, accounting for the difference between the surface mass balance (SMB) and the discharge of ice into an ocean or ice shelf. The SMB values are based on output of the regional climate model RACMO Version 2.3p2. For studying glacier flow and retrieving ice discharge we generated time series of ice velocity from data of different satellite radar sensor, with radar images of the satellites TerraSAR-X and TanDEM-X as main source. The study area comprises tributaries to the Larsen-A, Larsen Inlet, and Prince-Gustav-Channel embayments (region A), the glaciers calving into Larsen B embayment (region B), and the glaciers draining into the remnant part of Larsen B ice shelf in SCAR Inlet (region C). The glaciers of region A, where the buttressing ice shelf disintegrated in 1995, and of region B (ice shelf break-up in 2002) show continuing losses in ice mass, with significant reduction of losses after 2013. The mass balance numbers for grounded glacier area of the region A are Bn = −3.98 ± 0.33 Gt a-1 during 2011 to 2013 and Bn = −2.38 ± 0.18 Gt a-1 during 2013 to 2016. The corresponding numbers for region B are Bn = −5.75 ± 0.45 Gt a-1 and Bn = −2.32 ± 0.25 Gt a-1. The mass losses in region C during the two periods were modest, Bn = −0.54 ± 0.38 Gt a-1, respectively Bn = −0.58 ± 0.25 Gt a-1. The main share in the overall mass losses of the region were contributed by two glaciers: Drygalski Glacier contributing 61 % to the mass deficit of region A, and Hektoria and Green glaciers accounting for 67 % to the mass deficit of region B. Hektoria and Green glaciers accelerated significantly in 2010/2011, triggering elevation losses up to 19.5 m a-1 on the lower terminus and a rate of mass depletion of 3.88 Gt a-1 during the period 2011 to 2013. Slowdown of calving velocities and reduced calving fluxes in 2013 to 2016 coincided with years when the sea ice cover in front of the glaciers persisted during summer.

scholarly journals Changing pattern of ice flow and mass balance for glaciers discharging into the Larsen A and B embayments, Antarctic Peninsula, 2011 to 2016

2018 ◽  
Vol 12 (4) ◽  
pp. 1273-1291 ◽  
Author(s):  
Helmut Rott ◽  
Wael Abdel Jaber ◽  
Jan Wuite ◽  
Stefan Scheiblauer ◽  
Dana Floricioiu ◽  
...  
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Shelf ◽  
Satellite Mission ◽  
Surface Mass ◽  
Radar Images ◽  
Satellite Radar ◽  
The Difference

Abstract. We analysed volume change and mass balance of outlet glaciers on the northern Antarctic Peninsula over the periods 2011 to 2013 and 2013 to 2016, using high-resolution topographic data from the bistatic interferometric radar satellite mission TanDEM-X. Complementary to the geodetic method that applies DEM differencing, we computed the net mass balance of the main outlet glaciers using the mass budget method, accounting for the difference between the surface mass balance (SMB) and the discharge of ice into an ocean or ice shelf. The SMB values are based on output of the regional climate model RACMO version 2.3p2. To study glacier flow and retrieve ice discharge we generated time series of ice velocity from data from different satellite radar sensors, with radar images of the satellites TerraSAR-X and TanDEM-X as the main source. The study area comprises tributaries to the Larsen A, Larsen Inlet and Prince Gustav Channel embayments (region A), the glaciers calving into the Larsen B embayment (region B) and the glaciers draining into the remnant part of the Larsen B ice shelf in Scar Inlet (region C). The glaciers of region A, where the buttressing ice shelf disintegrated in 1995, and of region B (ice shelf break-up in 2002) show continuing losses in ice mass, with significant reduction of losses after 2013. The mass balance numbers for the grounded glacier area of region A are −3.98 ± 0.33 Gt a−1 from 2011 to 2013 and −2.38 ± 0.18 Gt a−1 from 2013 to 2016. The corresponding numbers for region B are −5.75 ± 0.45 and −2.32 ± 0.25 Gt a−1. The mass balance in region C during the two periods was slightly negative, at −0.54 ± 0.38 Gt a−1 and −0.58 ± 0.25 Gt a−1. The main share in the overall mass losses of the region was contributed by two glaciers: Drygalski Glacier contributing 61 % to the mass deficit of region A, and Hektoria and Green glaciers accounting for 67 % to the mass deficit of region B. Hektoria and Green glaciers accelerated significantly in 2010–2011, triggering elevation losses up to 19.5 m a−1 on the lower terminus during the period 2011 to 2013 and resulting in a mass balance of −3.88 Gt a−1. Slowdown of calving velocities and reduced calving fluxes in 2013 to 2016 coincided with years in which ice mélange and sea ice cover persisted in proglacial fjords and bays during summer.

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 A synthesis of remote sensing data on Wilkins Ice Shelf, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 211-218 ◽  
Author(s):  
D.G. Vaughan ◽  
D.R. Mantripp ◽  
J. Sievers ◽  
C.S.M. Doake
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Remote Sensing Data ◽  
Dynamic Effect ◽  
Remotely Sensed Data ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Limit Of Viability ◽  
The Antarctic

Wilkins Ice Shelf has an area of 16000 km2 and lies off the west coast of the Antarctic Peninsula bounded by Alexander, Latady, Charcot and Rothschild islands. Several ice shelves, including Wilkins, exist close to a climatic limit of viability. The recent disintegration of the neighbouring Wordie Ice Shelf has been linked to atmopsheric warming observed on the Antarctic Peninsula. The limit of ice-shelf viability thus appears to have migrated south. Should this continue, the question arises; how long will Wilkins Ice Shelf survive?Compared with the other ice shelves on the Antarctic Peninsula, few surface glaciological data have been collected on Wilkins Ice Shelf. We compare, contrast and combine a variety of remotely sensed data: the recently declassified GEOSAT Geodetic Mission altimetry, Landsat MSS and TM imagery, and radio-echo sounding data (RES), to study its structure and mass balance regime.We find that this shelf has an unusual mass balance regime and relies heavily for sustenance on in situ accumulation. Its response to a continued atmospheric warming may be significantly different from that of Wordie Ice Shelf. Wordie Ice Shelf was fed by several dynamic outlet glaciers which accelerated the disintegration process when the ice shelf fractured. Wilkins Ice Shelf by contrast is almost stagnant and is expected to respond by normal calving at the ice front. Changes in the accumulation rate or basal melt-rate may, however, dominate any dynamic effect. Over the last two decades the ice front positions have remained stable.

scholarly journals Characteristics of ice rises and ice rumples in Dronning Maud Land and Enderby Land, Antarctica

2020 ◽  
Vol 66 (260) ◽  
pp. 1064-1078
Author(s):  
Vikram Goel ◽  
Kenichi Matsuoka ◽  
Cesar Deschamps Berger ◽  
Ian Lee ◽  
Jørgen Dall ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Cores ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Past ◽  
Dronning Maud Land ◽  
The Antarctic

AbstractIce rises and rumples, locally grounded features adjacent to ice shelves, are relatively small yet play significant roles in Antarctic ice dynamics. Their roles generally depend upon their location within the ice shelf and the stage of the ice-sheet retreat or advance. Large, long-stable ice rises can be excellent sites for deep ice coring and paleoclimate study of the Antarctic coast and the Southern Ocean, while small ice rises tend to respond more promptly and can be used to reveal recent changes in regional mass balance. The coasts of Dronning Maud Land (DML) and Enderby Land in East Antarctica are abundant with these features. Here we review existing knowledge, presenting an up-to-date status of research in these regions with focus on ice rises and rumples. We use regional datasets (satellite imagery, surface mass balance and ice thickness) to analyze the extent and surface morphology of ice shelves and characteristic timescales of ice rises. We find that large parts of DML have been changing over the past several millennia. Based on our findings, we highlight ice rises suitable for drilling ice cores for paleoclimate studies as well as ice rises suitable for deciphering ice dynamics and evolution in the region.

scholarly journals Detecting high spatial variability of ice-shelf basal mass balance (Roi Baudouin ice shelf, Antarctica)

2017 ◽  
Author(s):  
Sophie Berger ◽  
Reinhard Drews ◽  
Veit Helm ◽  
Sainan Sun ◽  
Frank Pattyn
Keyword(s):  
Spatial Variability ◽  
Mass Balance ◽  
Mass Conservation ◽  
Atmospheric Model ◽  
Small Scale ◽  
Ice Shelf ◽  
Surface Mass ◽  
Ice Shelves ◽  
Shelf Slope ◽  
Grounding Line

Abstract. Ice shelves control the dynamic mass loss of ice sheets through buttressing and their integrity depends on the spatial variability of their basal mass balance (BMB), i.e., the difference between refreezing and melting. Here, we present a novel technique – based on satellite observations – to capture the small-scale variability in the BMB of ice-shelves. As a case study we apply the methodology to the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica and derive its yearly-averaged BMB at 10 m horizontal gridding. We use mass conservation within a Lagrangian framework based on high-resolution surface velocities, atmospheric-model surface mass balance and hydrostatic ice-thickness fields (derived from TanDEM-X surface elevation). Spatial derivatives are implemented using the total-variation differentiation, which avoids spatial averaging hence loss of spatial resolution. Our BMB field exhibits high detail and ranges from −14.8 to 8.6 m a−1 ice equivalent. Highest melt rates are found close to the grounding line where the basal ice-shelf slope is the steepest. The BMB field agrees well with on-site measurements from phase-sensitive radar, although unresolved spatial variations in firn density determined from profiling radar occur. We show that the surface expression of an englacial lake (0.7 × 1.3 km2 wide and 30 m deep) lowers by 0.5 to 1.4 m a−1, which we tentatively attribute to a transient adaptation to hydrostatic equilibrium. We find evidence for elevated melting beneath ice-shelf channels (with melting being concentrated on the channel's flanks). However, farther downstream from the grounding line, the majority of ice-shelf channels advect passively toward the ice-shelf front. Although the absolute, satellite-based BMB values remain uncertain, we have high confidence in the spatial variability on sub-kilometre scales. This study highlights expected challenges for a full coupling between ice and ocean models.

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.

scholarly journals Constraining variable density of ice shelves using wide-angle radar measurements

2016 ◽  
Vol 10 (2) ◽  
pp. 811-823 ◽  
Author(s):  
Reinhard Drews ◽  
Joel Brown ◽  
Kenichi Matsuoka ◽  
Emmanuel Witrant ◽  
Morgane Philippe ◽  
...  
Keyword(s):  
Mass Balance ◽  
Propagation Speed ◽  
Radar Data ◽  
Temporal Variations ◽  
Variable Density ◽  
Ice Thickness ◽  
Wide Angle ◽  
Ice Shelf ◽  
Surface Mass ◽  
Ice Shelves

Abstract. The thickness of ice shelves, a basic parameter for mass balance estimates, is typically inferred using hydrostatic equilibrium, for which knowledge of the depth-averaged density is essential. The densification from snow to ice depends on a number of local factors (e.g., temperature and surface mass balance) causing spatial and temporal variations in density–depth profiles. However, direct measurements of firn density are sparse, requiring substantial logistical effort. Here, we infer density from radio-wave propagation speed using ground-based wide-angle radar data sets (10 MHz) collected at five sites on Roi Baudouin Ice Shelf (RBIS), Dronning Maud Land, Antarctica. We reconstruct depth to internal reflectors, local ice thickness, and firn-air content using a novel algorithm that includes traveltime inversion and ray tracing with a prescribed shape of the depth–density relationship. For the particular case of an ice-shelf channel, where ice thickness and surface slope change substantially over a few kilometers, the radar data suggest that firn inside the channel is about 5 % denser than outside the channel. Although this density difference is at the detection limit of the radar, it is consistent with a similar density anomaly reconstructed from optical televiewing, which reveals that the firn inside the channel is 4.7 % denser than that outside the channel. Hydrostatic ice thickness calculations used for determining basal melt rates should account for the denser firn in ice-shelf channels. The radar method presented here is robust and can easily be adapted to different radar frequencies and data-acquisition geometries.

scholarly journals A synthesis of remote sensing data on Wilkins Ice Shelf, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 211-218 ◽  
Author(s):  
D.G. Vaughan ◽  
D.R. Mantripp ◽  
J. Sievers ◽  
C.S.M. Doake
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Remote Sensing Data ◽  
Dynamic Effect ◽  
Remotely Sensed Data ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Limit Of Viability ◽  
The Antarctic

Wilkins Ice Shelf has an area of 16000 km2 and lies off the west coast of the Antarctic Peninsula bounded by Alexander, Latady, Charcot and Rothschild islands. Several ice shelves, including Wilkins, exist close to a climatic limit of viability. The recent disintegration of the neighbouring Wordie Ice Shelf has been linked to atmopsheric warming observed on the Antarctic Peninsula. The limit of ice-shelf viability thus appears to have migrated south. Should this continue, the question arises; how long will Wilkins Ice Shelf survive? Compared with the other ice shelves on the Antarctic Peninsula, few surface glaciological data have been collected on Wilkins Ice Shelf. We compare, contrast and combine a variety of remotely sensed data: the recently declassified GEOSAT Geodetic Mission altimetry, Landsat MSS and TM imagery, and radio-echo sounding data (RES), to study its structure and mass balance regime. We find that this shelf has an unusual mass balance regime and relies heavily for sustenance on in situ accumulation. Its response to a continued atmospheric warming may be significantly different from that of Wordie Ice Shelf. Wordie Ice Shelf was fed by several dynamic outlet glaciers which accelerated the disintegration process when the ice shelf fractured. Wilkins Ice Shelf by contrast is almost stagnant and is expected to respond by normal calving at the ice front. Changes in the accumulation rate or basal melt-rate may, however, dominate any dynamic effect. Over the last two decades the ice front positions have remained stable.

scholarly journals The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

2015 ◽  
Vol 9 (5) ◽  
pp. 5097-5136
Author(s):  
J. M. van Wessem ◽  
S. R. M. Ligtenberg ◽  
C. H. Reijmer ◽  
W. J. van de Berg ◽  
M. R. van den Broeke ◽  
...  
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Surface Mass Balance ◽  
High Accumulation ◽  
Surface Mass ◽  
Ice Shelves ◽  
Meltwater Runoff ◽  
The Antarctic

Abstract. This study presents a high-resolution (~ 5.5 km) estimate of Surface Mass Balance (SMB) over the period 1979–2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a Firn Densification Model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in-situ SMB observations and discharge rates from 6 glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr−1 over the western AP (WAP) and below 500 mm we yr−1 on the eastern AP (EAP), not resolved by coarser data-sets such as ERA-Interim. The other SMB components are one order of magnitude smaller, with drifting snow sublimation the largest ablation term removing up to 100 mm we yr−1 of mass. Snowmelt is widespread over the AP, reaching 500 mm we yr−1 towards the northern ice shelves, but the meltwater mostly refreezes. As a result runoff fluxes are low, but still considerable (200 mm we yr−1) over the Larsen (B/C), Wilkins and George VI ice shelves. The average AP ice sheet integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr−1 with an interannual variability of 58 Gt yr−1, which is dominated by precipitation (PR) (365 ± 57 Gt yr−1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr−1), where PR is large (276 ± 47 Gt yr−1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr−1) and PR (84 ± 11 Gt yr−1). Total sublimation is 11 ± 2 Gt yr−1 and meltwater runoff into the ocean is 4 ± 4 Gt yr−1. There are no significant trends in any of the AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (−0.36 Gt yr−2).

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