scholarly journals Ocean mixing beneath Pine Island Glacier ice shelf, West Antarctica

2016 ◽  
Vol 121 (12) ◽  
pp. 8496-8510 ◽  
Author(s):  
Satoshi Kimura ◽  
Adrian Jenkins ◽  
Pierre Dutrieux ◽  
Alexander Forryan ◽  
Alberto C. Naveira Garabato ◽  
...  
Keyword(s):  
Ocean Mixing ◽  
West Antarctica ◽  
Ice Shelf ◽  
Glacier Ice

scholarly journals History of lower Pine Island Glacier, West Antarctica, from Landsat imagery

2002 ◽  
Vol 48 (163) ◽  
pp. 536-544 ◽  
Author(s):  
Robert A. Bindschadler
Keyword(s):  
Landsat Imagery ◽  
West Antarctica ◽  
Ice Shelf ◽  
Landsat Images ◽  
The North ◽  
Glacier Ice ◽  
History Of ◽  
Upper Bound Estimate ◽  
Full Period ◽  
Observation Period

AbstractA 28 year record of lower Pine Island Glacier, West Antarctica, constructed from 15 Landsat images, shows changes at the terminus, grounding zone and both margins. The north margin has expanded 5 km into the adjacent ice shelf in a sustained event that was underway in 1973 and may have begun in 1957. Between 1991 and 1997, this expansion ceased and a new region of rifting was created associated with an ice rise on the glacier’s floating tongue. Changes in the topography of a nearby ice rise are used to deduce an upper-bound estimate of a 134 m thinning of the adjacent ice shelf. On the south margin, widening was limited to 1 km over the observation period and is seen propagating downstream in an intermediate-dated image. New areas of crevassing are also evident in the grounding zone of the glacier. Ice loss by the calving of large tabular bergs vastly exceeds mass loss by calving of many small bergs. These observations are consistent with reported changes of the 1990s and indicate that changes in the flow of Pine Island Glacier have occurred over the full period of satellite observations.

scholarly journals Velocities of the Smith Glacier ice tongue and Dotson Ice Shelf, Walgreen Coast, Marie Byrd Land, West Antarctica

1994 ◽  
Vol 20 ◽  
pp. 101-109 ◽  
Author(s):  
B.K. Lucchitta ◽  
K.F. Mullins ◽  
C.E. Smith ◽  
J.G. Ferrigno
Keyword(s):  
Progressive Increase ◽  
West Antarctica ◽  
Velocity Measurements ◽  
Ice Shelf ◽  
Time Intervals ◽  
Time Period ◽  
Grounding Line ◽  
Glacier Ice

Velocity measurements were made for two time intervals on the Smith Glacier ice tongue (1973–88 and 1988–90) and three on the Dotson Ice Shelf (1972–88, 1973–88 and 1988–90). The Smith Glacier ice tongue velocities for the two intervals are similar near the grounding line but show a progressive increase toward the terminus in the late 1980s. The Dotson Ice Shelf velocities remained virtually constant during all three time intervals. The increased velocities of the Smith Glacier ice tongue may be attributed to a general loss of densely packed icebergs that buttressed the terminus during the 1970s but drifted out to sea during the late 1980s. The Smith Glacier ice tongue receded as much as 10 km between 1973 and 1988, the Dotson lee Shelf 5–7 km in the same time period. Similar observations of drifting and ca1ving were made for the adjacent Thwaites Glacier ice tongue. The cause of the loss of ice in the region is unknown but it may have been a change in winds or a warming of the air or water during the late 1980s.

scholarly journals Velocities of Thwaites Glacier and smaller glaciers along the Marie Byrd Land coast, West Antarctica

1998 ◽  
Vol 27 ◽  
pp. 47-53 ◽  
Author(s):  
C. E. Rosanova ◽  
B. K. Lucchitta ◽  
J. G. Ferrigno
Keyword(s):  
West Antarctica ◽  
Ice Shelf ◽  
Time Intervals ◽  
Ice Shelves ◽  
Radar Images ◽  
Ice Surface ◽  
Grounding Line ◽  
Glacier Ice ◽  
Surface Patterns ◽  
High Precipitation

Average velocities for time intervals ranging from < 1 to 15 years were measured by tracking ice-surface patterns on sequential Landsat and European Remote-sensing Satellite synthetic aperture radar images. Velocities ofThwaites Glacier range from 2.2 km a−1 above the grounding line to 3.4 km a−1 at the limit of measurements onThwaites Glacier ice tongue. The glacier increases in velocity by about 1 km a−1 where it crosses the grounding line. Over the period 1984-93, Thwaites Glacier ice tongue accelerated by about 0.6 kin a .Velocities of the floating part of several minor glaciers and some ice shelves are also determined: Land Glacier, 17—1.9 km a−1 ; DeVicq Glacier, 0.7-1.1 km a−1; Dotson Ice Shelf 0.2-0.5 km a−1; Gctz Ice Shelf, 0.2-0.8 km a−1; and Sulzberger Ice Shelf, 0.01 -0.02 km a−1. The high velocities along the Marie Byrd Land coast are consistent with the high precipitation rates over West Antarctica and, for some of the glaciers, the lack of buttressing ice shelves.

scholarly journals Variability of basal melt beneath the Pine Island Glacier ice shelf, West Antarctica

2011 ◽  
Vol 57 (204) ◽  
pp. 581-595 ◽  
Author(s):  
Robert Bindschadler ◽  
David G. Vaughan ◽  
Patricia Vornberger
Keyword(s):  
Landsat Imagery ◽  
Warm Water ◽  
West Antarctica ◽  
Ice Shelf ◽  
Amundsen Sea ◽  
Model Calculations ◽  
Annual Variations ◽  
Ice Surface ◽  
Grounding Line ◽  
Glacier Ice

AbstractObservations from satellite and airborne platforms are combined with model calculations to infer the nature and efficiency of basal melting of the Pine Island Glacier ice shelf, West Antarctica, by ocean waters. Satellite imagery shows surface features that suggest ice-shelf-wide changes to the ocean’s influence on the ice shelf as the grounding line retreated. Longitudinal profiles of ice surface and bottom elevations are analyzed to reveal a spatially dependent pattern of basal melt with an annual melt flux of 40.5 Gt a−1. One profile captures a persistent set of surface waves that correlates with quasi-annual variations of atmospheric forcing of Amundsen Sea circulation patterns, establishing a direct connection between atmospheric variability and sub-ice-shelf melting. Ice surface troughs are hydrostatically compensated by ice-bottom voids up to 150 m deep. Voids form dynamically at the grounding line, triggered by enhanced melting when warmer-than-average water arrives. Subsequent enlargement of the voids is thermally inefficient (4% or less) compared with an overall melting efficiency beneath the ice shelf of 22%. Residual warm water is believed to cause three persistent polynyas at the ice-shelf front seen in Landsat imagery. Landsat thermal imagery confirms the occurrence of warm water at the same locations.

scholarly journals Velocities of the Smith Glacier ice tongue and Dotson Ice Shelf, Walgreen Coast, Marie Byrd Land, West Antarctica

1994 ◽  
Vol 20 ◽  
pp. 101-109 ◽  
Author(s):  
B.K. Lucchitta ◽  
K.F. Mullins ◽  
C.E. Smith ◽  
J.G. Ferrigno
Keyword(s):  
Progressive Increase ◽  
West Antarctica ◽  
Velocity Measurements ◽  
Ice Shelf ◽  
Time Intervals ◽  
Time Period ◽  
Grounding Line ◽  
Glacier Ice

Velocity measurements were made for two time intervals on the Smith Glacier ice tongue (1973–88 and 1988–90) and three on the Dotson Ice Shelf (1972–88, 1973–88 and 1988–90). The Smith Glacier ice tongue velocities for the two intervals are similar near the grounding line but show a progressive increase toward the terminus in the late 1980s. The Dotson Ice Shelf velocities remained virtually constant during all three time intervals. The increased velocities of the Smith Glacier ice tongue may be attributed to a general loss of densely packed icebergs that buttressed the terminus during the 1970s but drifted out to sea during the late 1980s. The Smith Glacier ice tongue receded as much as 10 km between 1973 and 1988, the Dotson lee Shelf 5–7 km in the same time period. Similar observations of drifting and ca1ving were made for the adjacent Thwaites Glacier ice tongue. The cause of the loss of ice in the region is unknown but it may have been a change in winds or a warming of the air or water during the late 1980s.

scholarly journals Subglacial bathymetry and sediment layer distribution beneath the Pine Island Glacier ice shelf, West Antarctica, modeled using aerogravity and autonomous underwater vehicle data

2013 ◽  
Vol 54 (64) ◽  
pp. 27-32 ◽  
Author(s):  
Atsuhiro Muto ◽  
Sidhar Anandakrishnan ◽  
Richard B. Alley
Keyword(s):  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Flow Speed ◽  
Ocean Bottom ◽  
Sediment Layer ◽  
West Antarctica ◽  
Ice Shelf ◽  
The North ◽  
Submarine Ridge ◽  
Glacier Ice

Abstract Pine Island Glacier (PIG), West Antarctica, has been experiencing acceleration in its flow speed and mass loss for nearly two decades, driven in part by an increase in the delivery of relatively warm Circumpolar Deep Water (CDW). However, at present, the configuration of the sub-ice-shelf cavity and bed conditions beneath the PIG ice shelf that dictate such oceanic influences remain poorly understood. Here, we use aerogravity data and ocean bottom depths measured by an autonomous underwater vehicle (AUV) to model the bathymetry and sediment layer thickness beneath the PIG ice shelf. Results reveal that the deep basins, previously found by AUV on both landward and seaward sides of a submarine ridge, extend substantially to the north and south. The water column thickness of the basins reaches 400-550 m on the landward side of the ridge and 500-600 m on the seaward side. The sediment layer covers the whole expanse of the seabed beneath the ice shelf, and the thickness is in the range ∼200-1000 m. The thinnest sediments (<200 m) are found on the seaward slope of the submarine ridge, suggesting that erosion by advancing ice may have been concentrated in the lee of the topographic high.

scholarly journals Sensitivity of Pine Island Glacier, West Antarctica, to changes in ice-shelf and basal conditions: a model study

2002 ◽  
Vol 48 (163) ◽  
pp. 552-558 ◽  
Author(s):  
Marjorie Schmeltz ◽  
Eric Rignot ◽  
Todd K. Dupont ◽  
Douglas R. MacAyeal
Keyword(s):  
Shear Stress ◽  
Element Model ◽  
Shelf Area ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Stream ◽  
Model Study ◽  
Grounding Line ◽  
Glacier Velocity ◽  
Basal Shear

AbstractWe use a finite-element model of coupled ice-stream/ice-shelf flow to study the sensitivity of Pine Island Glacier, West Antarctica, to changes in ice-shelf and basal conditions. By tuning a softening coefficient of the ice along the glacier margins, and a basal friction coefficient controlling the distribution of basal shear stress underneath the ice stream, we are able to match model velocity to that observed with interferometric synthetic aperture radar (InSAR). We use the model to investigate the effect of small perturbations on ice flow. We find that a 5.5–13% reduction in our initial ice-shelf area increases the glacier velocity by 3.5–10% at the grounding line. The removal of the entire ice shelf increases the grounding-line velocity by > 70%. The changes in velocity associated with ice-shelf reduction are felt several tens of km inland. Alternatively, a 5% reduction in basal shear stress increases the glacier velocity by 13% at the grounding line. By contrast, softening of the glacier side margins would have to be increased a lot more to produce a comparable change in ice velocity. Hence, both the ice-shelf buttressing and the basal shear stress contribute significant resistance to the flow of Pine Island Glacier.

scholarly journals Thermohaline structure and circulation beneath the Langhovde Glacier ice shelf in East Antarctica

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Masahiro Minowa ◽  
Shin Sugiyama ◽  
Masato Ito ◽  
Shiori Yamane ◽  
Shigeru Aoki
Keyword(s):  
Freezing Point ◽  
East Antarctica ◽  
Ice Shelf ◽  
Rate Estimate ◽  
Ice Shelves ◽  
Plume Water ◽  
Warm Deep Water ◽  
Glacier Ice ◽  
Basal Melting

AbstractBasal melting of ice shelves is considered to be the principal driver of recent ice mass loss in Antarctica. Nevertheless, in-situ oceanic data covering the extensive areas of a subshelf cavity are sparse. Here we show comprehensive structures of temperature, salinity and current measured in January 2018 through four boreholes drilled at a ~3-km-long ice shelf of Langhovde Glacier in East Antarctica. The measurements were performed in 302–12 m-thick ocean cavity beneath 234–412 m-thick ice shelf. The data indicate that Modified Warm Deep Water is transported into the grounding zone beneath a stratified buoyant plume. Water at the ice-ocean interface was warmer than the in-situ freezing point by 0.65–0.95°C, leading to a mean basal melt rate estimate of 1.42 m a−1. Our measurements indicate the existence of a density-driven water circulation in the cavity beneath the ice shelf of Langhovde Glacier, similar to that proposed for warm-ocean cavities of larger Antarctic ice shelves.

scholarly journals Sensitivity of the dynamics of Pine Island Glacier, West Antarctica, to climate forcing for the next 50 years

2014 ◽  
Vol 8 (5) ◽  
pp. 1699-1710 ◽  
Author(s):  
H. Seroussi ◽  
M. Morlighem ◽  
E. Rignot ◽  
J. Mouginot ◽  
E. Larour ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Three Dimensional ◽  
Major Contributor ◽  
West Antarctica ◽  
Climatic Impact ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Grounding Line

Abstract. Pine Island Glacier, a major contributor to sea level rise in West Antarctica, has been undergoing significant changes over the last few decades. Here, we employ a three-dimensional, higher-order model to simulate its evolution over the next 50 yr in response to changes in its surface mass balance, the position of its calving front and ocean-induced ice shelf melting. Simulations show that the largest climatic impact on ice dynamics is the rate of ice shelf melting, which rapidly affects the glacier speed over several hundreds of kilometers upstream of the grounding line. Our simulations show that the speedup observed in the 1990s and 2000s is consistent with an increase in sub-ice-shelf melting. According to our modeling results, even if the grounding line stabilizes for a few decades, we find that the glacier reaction can continue for several decades longer. Furthermore, Pine Island Glacier will continue to change rapidly over the coming decades and remain a major contributor to sea level rise, even if ocean-induced melting is reduced.

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