Summertime water masses off the northern Larsen C Ice Shelf, Antarctica

Nicholls, Keith W.; Pudsey, Carol J.; Morris, Peter

doi:10.1029/2004gl019924

Cited by 45 publications

(106 citation statements)

References 13 publications

(13 reference statements)

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“…Conversely, other research indicates that it is unlikely that temperature changes of the deep Weddell Sea are having a major impact on melt rates at the base of Larsen C Ice Shelf (Nicholls et al, 2004). Observations show that although MWDW is present at the ice front, the Ice Shelf Water is not derived from this directly, but from MWDW pre-conditioned by winter cooling and by salinification from sea-ice production.…”

Section: Larsen C Ice Shelfmentioning

confidence: 81%

“…This suggests that enhanced ocean-driven melting could provide a link between regional climate warming and successive disintegration of these sections of the Larsen Ice Shelf. Oceanographic observations in this region are limited, however, and another study has shown that regional ocean warming may not have had a major impact on basal melt rates (Nicholls et al, 2004). Other changes in the ice-shelf dynamics prior to their collapse have also been detected, such as an acceleration in iceshelf flow of up to 50%, revealed through observations using satellite radar interferometry for the Larsen B Ice Shelf Vieli et al, 2006;Skvarca et al, 2003).…”

Section: Larsen a And Larsen B Ice Shelvesmentioning

confidence: 98%

“…The mean rate of elevation change of Larsen C was 0.08 ± 0.04 ma −1 . There is evidence that nearby Weddell Deep Waters (WDW) have warmed (Robertson et al, 2002), and in 2002 oceanographic measurements showed large quantities of Modified Weddell Deep Waters (MWDW) present in front of the northern Larsen C (Nicholls et al, 2004). The study by Shepherd et al (2003) stated that although basal melt rates are uncertain, enhanced ocean melting has been and is thinning the Larsen Ice Shelf.…”

Section: Larsen C Ice Shelfmentioning

confidence: 99%

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Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years

2010

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Abstract. In recent decades, seven out of twelve ice shelves around the Antarctic Peninsula (AP) have either retreated significantly or have been almost entirely lost. At least some of these retreats have been shown to be unusual within the context of the Holocene and have been widely attributed to recent atmospheric and oceanic changes. To date, measurements of the area of ice shelves on the AP have either been approximated, or calculated for individual shelves over dissimilar time intervals. Here we present a new dataset containing up-to-date and consistent area calculations for each of the twelve ice shelves on the AP over the past five decades. The results reveal an overall reduction in total ice-shelf area by over 28 000 km 2 since the beginning of the period. Individual ice shelves show different rates of retreat, ranging from slow but progressive retreat to abrupt collapse. We discuss the pertinent features of each ice shelf and also broad spatial and temporal patterns in the timing and rate of retreat. We believe that an understanding of this diversity and what it implies about the underlying dynamics and control will provide the best foundation for developing a reliable predictive skill for ice-shelf change.

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Section: Larsen C Ice Shelfmentioning

confidence: 81%

Section: Larsen a And Larsen B Ice Shelvesmentioning

confidence: 98%

Section: Larsen C Ice Shelfmentioning

confidence: 99%

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Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years

2010

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“…Here, an increased freshwater flux due to enhanced melting of ice shelves fringing the Amundsen Sea was suggested to be the cause. The thinning of Larsen Ice Shelf was attributed to increased basal melting due to warmer shelf waters (Shepherd et al, 2003), although a warming on the western Weddell Sea continental shelf lacks observations (e.g., Nicholls et al, 2004). Nevertheless, the presence of ISW with temperatures below surface freezing at the northern front of Larsen C Ice Shelf (Fig.…”

Section: Winter Conditionsmentioning

confidence: 99%

“…In austral summer 2006/07 the southernmost stations were occupied at ∼66 • S, near the northern front of Larsen C ice shelf (Fig. 1a) where Nicholls et al (2004) already had observed the outflow of glacial melt water.…”

Section: Observationsmentioning

confidence: 99%

On the freshening of the northwestern Weddell Sea continental shelf

et al. 2011

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Abstract. We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ∼64 • S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.

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The structure and effect of suture zones in the Larsen C Ice Shelf, Antarctica

McGrath

Steffen

Holland

et al. 2014

J. Geophys. Res. Earth Surf.

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Ice shelf fractures frequently terminate where they encounter suture zones, regions of material heterogeneity that form between meteoric inflows in ice shelves. This heterogeneity can consist of marine ice, meteoric ice with modified rheological properties, or the presence of fractures. Here, we use radar observations on the Larsen C Ice Shelf, Antarctica, to investigate (i) the termination of a 25 km long rift in the Churchill Peninsula suture zone, which was found to contain~60 m of accreted marine ice, and (ii) the along-flow evolution of a suture zone originating at Cole Peninsula. We determine a steady state field of basal melting/freezing rates and apply it to a flowline model to delineate the along-flow evolution of layers within the ice shelf. The thickening surface wedge of locally accumulated meteoric ice, which likely has limited lateral variation in its mechanical properties, accounts for~60% of the total ice thickness near the calving front. Thus, we infer that the lower 40% of the ice column and the material heterogeneities present there are responsible for resisting fracture propagation and thereby delaying tabular calving events, as demonstrated in the >40 year time series leading up to the 2004/2005 calving event for Larsen C. This likely represents a highly sensitive aspect of ice shelf stability, as changes in the oceanic forcing may lead to the loss of this heterogeneity.

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Summertime water masses off the northern Larsen C Ice Shelf, Antarctica

Cited by 45 publications

References 13 publications

Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years

Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years

On the freshening of the northwestern Weddell Sea continental shelf

The structure and effect of suture zones in the Larsen C Ice Shelf, Antarctica

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