Tracking the Cracking: a Holistic Analysis of Rapid Ice Shelf Fracture Using Seismology, Geodesy, and Satellite Imagery on the Pine Island Glacier Ice Shelf, West Antarctica

Abstract Satellite imagery is used as a basis to review and critique the results of studies at the mouths of Ice Streams Β and C and Crary Ice Rise. In many cases, these past analyses are extended by taking advantage of the broad coverage within each image. New perspectives are provided by the image data and some longstanding controversies are resolved. The grounding line is easily delineated and mapped in areas covered by imagery. Extensive areas of grounded ice with complex patterns of flow stripes are identified on the flanks of Crary Ice Rise. The imagery also allows a corrected map of surface topography in the vicinity of the Downstream Β camp. New questions are posed by hitherto unseen features. Data from the IGY traverse of the Ross Ice Shelf in 1957 are included to demonstrate that large changes have occurred in the past almost 30 years in the area upstream of Crary Ice Rise. These changes include modifications in the surface topography, elimination of crevasses and increases in the ice thickness by approximately 60 m.

Download Full-text

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

Journal of Glaciology ◽

10.3189/172756502781831052 ◽

2002 ◽

Vol 48 (163) ◽

pp. 536-544 ◽

Cited By ~ 21

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.

Download Full-text

Siple Coast Project research of Crary Ice Rise and the mouths of Ice Streams B and C, West Antarctica: review and new perspectives

Journal of Glaciology ◽

10.3189/s0022143000016439 ◽

1993 ◽

Vol 39 (133) ◽

pp. 538-552 ◽

Cited By ~ 1

Author(s):

Robert Bindschadler

Keyword(s):

Surface Topography ◽

Satellite Imagery ◽

Image Data ◽

Ice Thickness ◽

West Antarctica ◽

Ice Shelf ◽

Ice Streams ◽

Ross Ice Shelf ◽

The Past ◽

Grounding Line

AbstractSatellite imagery is used as a basis to review and critique the results of studies at the mouths of Ice Streams Β and C and Crary Ice Rise. In many cases, these past analyses are extended by taking advantage of the broad coverage within each image. New perspectives are provided by the image data and some longstanding controversies are resolved. The grounding line is easily delineated and mapped in areas covered by imagery. Extensive areas of grounded ice with complex patterns of flow stripes are identified on the flanks of Crary Ice Rise. The imagery also allows a corrected map of surface topography in the vicinity of the Downstream Β camp. New questions are posed by hitherto unseen features. Data from the IGY traverse of the Ross Ice Shelf in 1957 are included to demonstrate that large changes have occurred in the past almost 30 years in the area upstream of Crary Ice Rise. These changes include modifications in the surface topography, elimination of crevasses and increases in the ice thickness by approximately 60 m.

Download Full-text

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

Annals of Glaciology ◽

10.3189/1994aog20-1-101-109 ◽

1994 ◽

Vol 20 ◽

pp. 101-109 ◽

Cited By ~ 1

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.

Download Full-text

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

Annals of Glaciology ◽

10.3189/1998aog27-1-47-53 ◽

1998 ◽

Vol 27 ◽

pp. 47-53 ◽

Cited By ~ 13

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.

Download Full-text

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

Journal of Glaciology ◽

10.3189/002214311797409802 ◽

2011 ◽

Vol 57 (204) ◽

pp. 581-595 ◽

Cited By ~ 57

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.

Download Full-text

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

Annals of Glaciology ◽

10.1017/s026030550001630x ◽

1994 ◽

Vol 20 ◽

pp. 101-109 ◽

Cited By ~ 3

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.

Download Full-text

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

Annals of Glaciology ◽

10.3189/2013aog64a110 ◽

2013 ◽

Vol 54 (64) ◽

pp. 27-32 ◽

Cited By ~ 17

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.

Download Full-text

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

Journal of Glaciology ◽

10.3189/172756502781831061 ◽

2002 ◽

Vol 48 (163) ◽

pp. 552-558 ◽

Cited By ~ 47

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.

Download Full-text