The motion field of northern Larsen Ice Shelf, Antarctic Peninsula, derived from satellite imagery

Rack, Wolfgang; Rott, Helmut; Siegel, A.; Skvarca, Pedro

doi:10.3189/172756499781821120

Cited by 20 publications

(22 citation statements)

References 13 publications

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“…By comparing Figure b with Figure c, it is quite clear that flow acceleration occurred at the upstream of Drygalski Glacier flow unit from 1979–1986 to 1986–1988, while the acceleration magnitude decreased rapidly along the flow direction toward downstream. This flow pattern was likely attributed to the lateral drag from shear margin of the near‐stagnant Seal Nunataks and the backstress from Lindenberg Island [ Rack et al , ; Rott et al , ]. The flow velocity of the northern ice front near Sobral Peninsula increased by 11.5% from 1979–1986 to 1986–1988, comparable to the 15% velocity increase from 1975–1986 to 1986–1989 reported by Bindschadler et al [].…”

Section: Historical Ice Velocity Fields Over Larsen Ice Shelfmentioning

confidence: 99%

Revealing the early ice flow patterns with historical Declassified Intelligence Satellite Photographs back to 1960s

Wang

Liu

et al. 2016

Geophysical Research Letters

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The reconnaissance ARGON satellites collected the earliest images of Antarctica from space dating back to the 1960s, providing valuable historical baseline information for studying polar ice sheets. Those photographs are underutilized for ice motion mapping, due to lack of sufficient ground controls for image orthorectification. In this study, we orthorectified the ARGON photographs by fully exploiting the metric qualities of WorldView satellite images: very high spatial resolution and precise geolocation. Through a case study over Larsen Ice Shelf, we demonstrated that the camera model with bundle block adjustment can achieve geolocation accuracy of better than the nominal resolution (140 m) for orthorectifying ARGON images, with WorldView imagery as ground control source. This allowed us to extend the ice velocity records of Larsen Ice Shelf back into 1960s~1970s for the first time. The retrospective analysis revealed that acceleration of the collapsed Larsen B occurred much earlier than previously thought.

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Section: Historical Ice Velocity Fields Over Larsen Ice Shelfmentioning

confidence: 99%

Revealing the early ice flow patterns with historical Declassified Intelligence Satellite Photographs back to 1960s

Wang

Liu

et al. 2016

Geophysical Research Letters

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“…To reduce the effects of possible intradecadal fluctuations in these parameters, observations spanning several decades are required. Such long‐term observations also contextualize any observed rapid change, such as may be observed prior to ice shelf collapse [e.g., Doake and Vaughan , 1991; Rack et al , 1999], and may, in turn, help to indirectly constrain changes in local climate conditions (e.g., ocean temperature), especially those covering the mid‐1900s when Antarctic observations of any kind were infrequent at best.…”

Section: Introductionmentioning

confidence: 99%

Velocity change of the Amery Ice Shelf, East Antarctica, during the period 1968–1999

et al. 2007

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[1] Historic velocity measurements of Antarctica's ice sheet represent vital baseline values that allow ice flow velocity variations to be observed over multidecadal timescales, such as those due to climate change. Using velocity values derived from geodetic quality measurements made in the 1960s and from more recent GPS and remote sensing studies during the 1990s, we examine the variability of ice flow velocities of the northern Amery Ice Shelf, East Antarctica, over the 30-year period, 1968-1999. The historic ice shelf velocities are reexamined using original field notes and the previous data analyses are shown to be erroneous, yielding positional and velocity errors of up to 4 km and 150 m/yr respectively. Once corrected, these historic measurements are shown to be in close (1-5 m/yr) general agreement with GPS-derived velocities from the 1990s at similar geographical locations, providing one of the first precise constraints on multidecadal ice shelf velocity variations on a large Antarctic ice shelf. Comparison of the terrestrial and GPS velocities with spatially dense velocity measurements from remote sensing imagery reveals a systematic bias in the latter of up to ±30 m/yr, mostly due to propagation of unmodeled vertical ice shelf motion due to tides and atmospheric pressure variations. We therefore excluded the remote sensing velocities from further comparison and suggest caution in the interpretation of similarly derived ice shelf velocities. Velocity differences between the GPS and terrestrial surveys were compared at nine geographical locations suggesting a small ($2.2 m/yr or $0.6%), but statistically significant, slowdown of the ice shelf.

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“…The ice shelf in Prince Gustav Channel collapsed between 1992 and 1995 (Rott et al, 1996). Larsen A collapsed in 1995 (Rott et al, 1996), and Larsen B followed in 2002 (Rack and Rott, 2004).…”

Section: And Glassermentioning

confidence: 99%

“…However, very few have studied ice shelf velocities using the correlation method. Bindschadler et al (1994) and Rack et al (1999) derived velocities using this method on the relatively small Larsen A ice shelf. Skvarca (1994) …”

Section: Introductionmentioning

confidence: 99%

Monitoring ice shelf velocities from repeat MODIS and Landsat data – a method study on the Larsen C ice shelf, Antarctic Peninsula, and 10 other ice shelves around Antarctica

2010

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Abstract.We investigate the velocity field of the Larsen C ice shelf, Antarctic Peninsula, over the periods 2002-2006 and 2006-2009 based on repeat optical satellite data. The velocity field of the entire ice shelf is measured using repeat low resolution MODIS data (250 m spatial resolution). The measurements are validated for two ice shelf sections against repeat medium resolution Landsat 7 ETM+ pan data (15 m spatial resolution). Horizontal surface velocities are obtained through image matching using both orientation correlation operated in the frequency domain and normalized crosscorrelation operated in the spatial domain, and the two methods compared. The uncertainty in the displacement measurements turns out to be about one fourth of the pixel size for the MODIS derived data, and about one pixel for the Landsat derived data. The difference between MODIS and Landsat based speeds is −15.4 m a −1 and 13.0 m a −1 , respectively, for the first period for the two different validation sections on the ice shelf, and −26.7 m a −1 and 27.9 m a −1 for the second period for the same sections. This leads us to conclude that repeat MODIS images are well suited to measure ice shelf velocity fields and monitor their changes over time. Orientation correlation seems better suited for this purpose because it produces fewer mismatches, is able to match images with regular noise and data voids, and is faster. Since it can match images with regular data voids it is possible to match Landsat 7 ETM+ images even after the 2003 failure of the Scan Line Corrector (SLC off) that leaves significant image stripes with no data. Image matching based on the original 12-bit radiometric resolution MODIS data produced slightly better results than using the 8-bit version of the same images. Streamline interpolation from the obtained surface velocity field on Larsen C indicates ice travel times of up to 450 to 550 years between the inland boundary and the ice shelf edge. In a Correspondence to: T. Haug (torborg.haug@geo.uio.no) second step of the study we test our method successfully on 10 other ice shelves around Antarctica demonstrating that the approach presented could in fact be used for large scale monitoring of ice shelf dynamics.

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The motion field of northern Larsen Ice Shelf, Antarctic Peninsula, derived from satellite imagery

Cited by 20 publications

References 13 publications

Revealing the early ice flow patterns with historical Declassified Intelligence Satellite Photographs back to 1960s

Revealing the early ice flow patterns with historical Declassified Intelligence Satellite Photographs back to 1960s

Velocity change of the Amery Ice Shelf, East Antarctica, during the period 1968–1999

Monitoring ice shelf velocities from repeat MODIS and Landsat data – a method study on the Larsen C ice shelf, Antarctic Peninsula, and 10 other ice shelves around Antarctica

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