Iceberg calving rates from northern Ellesmere Island ice caps, Canadian Arctic, 1999–2003

Williamson, Scott; Sharp, Martin; Dowdeswell, Julian A.; Benham, Toby

doi:10.3189/002214308785837048

Cited by 39 publications

(60 citation statements)

References 30 publications

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“…Iceberg calving rates have also been derived for several other large ice caps and outlet glaciers in the Arctic. In the Russian archipelago of Severnaya Zemlya, the 5500 km 2 Academy of Sciences Ice Cap calves 0.65 km 3 a −1 , and the 14,000 km 2 Devon and 19,500 km 2 Agassiz ice caps in Arctic Canada produce about 0.55 km 3 a −1 and 0.67 km 3 a −1 of icebergs, respectively [ Dowdeswell et al , 2002; Burgess et al , 2005; Williamson et al , 2008]. Short and Gray [2005] also calculate that three eastward flowing outlet glaciers of the Prince of Wales Ice Cap on Canadian Ellesmere Island together produce 2.8 km 3 a −1 , with Trinity Glacier alone calving 2.3 km 3 a −1 of ice.…”

Section: Discussionmentioning

confidence: 99%

Iceberg calving flux and mass balance of the Austfonna ice cap on Nordaustlandet, Svalbard

et al. 2008

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[1] Satellite radar interferometry, 60 MHz airborne ice-penetrating radar data, and visible band satellite imagery were used to calculate the velocity structure, ice thickness, and the changing ice-marginal extent of Austfonna (8000 km 2 and 2500 km 3 ), the largest ice cap in the Eurasian Arctic. Ice cap motion is generally less than about 10 m a À1 , except where faster flowing curvilinear features with velocities of several tens to over 200 m a À1 are present. Most drainage basins of Austfonna have undergone ice-marginal retreat over the past few decades at an average of a few tens of meters per year. Integrating margin change around the whole ice cap gives a total area loss of about 10 km 2 a À1 . Iceberg flux from the marine margins of Austfonna is about 2.5 ± 0.5 km 3 a À1 (water equivalent), about 45% of the total calving flux from the whole Svalbard archipelago. When mass loss by iceberg production is taken into account, the total mass balance of Austfonna is negative by between about 2.5 and 4.5 km 3 a À1 . This iceberg flux represents about 33 ± 5% of total annual mass loss from Austfonna, with the remainder lost through surface ablation. Iceberg flux should be included in calculations of the total mass balance of the many large Arctic ice caps, including those located in the Russian and Canadian Arctic that end in tidewater. The neglect of this term has led to underestimates of mass loss from these ice caps and, thus, to underestimates of the contribution of Arctic ice caps to global sea level rise.

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Section: Discussionmentioning

confidence: 99%

Iceberg calving flux and mass balance of the Austfonna ice cap on Nordaustlandet, Svalbard

et al. 2008

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“…Many of them are tidewater glaciers located in the high-precipitation coastal areas [39,41,42]. Independent of this surge behaviour, glacier ice velocities during the summer are typically an order of magnitude larger than the mean annual velocities, and summer calving rates are 2-8 times larger than the annual average [41,43]. Other studies point to a high interannual variability of the velocities of the large outlet glaciers [44].…”

Section: Study Area and Data Sourcesmentioning

confidence: 97%

“…There is a large variability in the observed velocities, due to the different dynamic behaviour of the various glaciers. Some glaciers present a surge-type behaviour [42] or high seasonal and interannual variability of their velocities [43]. We can broadly group our studied glacier into three groups: (1) fast flowing with winter velocities greater than 600 m year −1 ; (2) medium flowing with winter velocities within 50-200 m year −1 ; and (3) slow flowing with speeds less than 50 m year −1 .…”

Section: Offset Tracking Velocity Mapping Of Southern Ellesmere's Icementioning

confidence: 99%

“…What is special in our application of the intensity offset tracking technique is that we retrieved the surface velocity fields exclusively from range offsets using ascending and descending passes. We also applied differential interferometry for the same areas in order to establish a comparison on the performance of both methodologies in glaciers with different dynamic regimes [42,43]. Sentinel-1 IW TOPS mode data was already tested with the offset tracking methodology by Nagler et al [21] giving successful region-wide results for the ice velocity field of Greenland.…”

Section: Comparison With Previous Studiesmentioning

confidence: 99%

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Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic

Sánchez-Gámez

Navarro

2017

Remote Sensing

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Abstract:The Terrain Observation by Progressive Scans (TOPS) acquisition mode of the Sentinel-1 mission provides a wide coverage per acquisition with resolutions of 5 m in range and 20 m in azimuth, which makes this acquisition mode attractive for glacier velocity monitoring. Here, we retrieve surface velocities from the southern Ellesmere Island ice caps (Canadian Arctic) using both offset tracking and Differential Interferometric Synthetic Aperture Radar (D-InSAR) techniques and combining ascending and descending passes. We optimise the offset tracking technique by omitting the azimuth offsets. By doing so, we are able to improve the final resolution of the velocity product, as Sentinel-1 shows a lower resolution in the azimuth direction. Simultaneously, we avoid the undesired ionospheric effect manifested in the data as azimuth streaks. The D-InSAR technique shows its merits when applied to slow-moving areas, while offset tracking is more suitable for fast-moving areas. This research shows that the methods used here are complementary and the use of both to determine glacier velocities is better than only using one or the other. We observe glacier surface velocities of up to 1200 m year −1 for the fastest tidewater glaciers. The land-terminating glaciers show typical velocities between 12 and 33 m year −1 , though with peaks up to 150 m year −1 in narrowing zones of the confining valleys.

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“…From 1961 to 2003 the ice caps and ice fields of the Canadian Arctic contributed 8% of the total global sea level rise that could be attributed to the melting of ice caps and glaciers [ Dyurgerov and Meier , 2005]. Current estimates are, however, based on the results of mass balance monitoring of a relatively small number of generally small ice masses, and there is only limited information about the extent and causes of ice cap area and volume change in the region [ Burgess and Sharp , 2004, 2008; Burgess et al , 2005; Mair et al , 2005; Abdalati et al , 2004; Williamson et al , 2008]. It is important to obtain as comprehensive a picture as possible of the recent and current mass balance status of these large ice caps, and those in other parts of the Arctic [ Dowdeswell et al , 2002, 2008], in order to assess their contribution to recent global sea level rise and predict the contribution that may be expected over the coming decades and centuries.…”

Section: Introductionmentioning

confidence: 99%

Mass balance of the Prince of Wales Icefield, Ellesmere Island, Nunavut, Canada

Mair¹,

Burgess²,

Sharp³

et al. 2009

J. Geophys. Res.

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[1] This paper estimates the mass balance of the Prince of Wales Icefield, Ellesmere Island, Canada, averaged over four decades, from measurements of surface mass balance (SMB) and iceberg calving. Shallow ice core net accumulation measurements and annual mass balance stake measurements are used in conjunction with a digital elevation model and knowledge of the location of the dominant moisture source for precipitation over the ice cap to interpolate and extrapolate spatial patterns of SMB across the Prince of Wales Icefield. The contribution of iceberg calving to the mass balance is calculated from estimates of (1) the annual volume of ice discharged at the major tidewater glacier termini and (2) the annual volume loss or gain due to terminus fluctuations. Two different approaches to determining the SMB conclude that the SMB of the ice field is approximately in balance (average equals À0.1 ± 0.4 km 3 w.e. a À1, where w.e. means water equivalent) largely because of its proximity to the main year-round moisture source that is the Smith Sound portion of the North Open Water polynya. Iceberg calving is a highly significant component of mass loss (À1.9 ± 0.2 km 3 w.e. a À1 ) and is sufficient to make the overall mass balance of the ice field averaged over the period 1963-2003 clearly negative (À2 ± 0.45 km 3 w.e. a À1 , equivalent to a mean-specific mass balance across the ice field of À0.1 m w.e. a À1). The Prince of Wales Icefield contributes $0.005 mm a À1 to global eustatic sea level rise.

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Iceberg calving rates from northern Ellesmere Island ice caps, Canadian Arctic, 1999–2003

Cited by 39 publications

References 30 publications

Iceberg calving flux and mass balance of the Austfonna ice cap on Nordaustlandet, Svalbard

Iceberg calving flux and mass balance of the Austfonna ice cap on Nordaustlandet, Svalbard

Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic

Mass balance of the Prince of Wales Icefield, Ellesmere Island, Nunavut, Canada

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