Annual warming episodes in seawater temperatures in McMurdo Sound in relationship to endogenous ice in notothenioid fish

2003 ◽  
Vol 15 (3) ◽  
pp. 333-338 ◽  
Author(s):  
BEN M. HUNT ◽  
KEVIN HOEFLING ◽  
CHI-HING C. CHENG
Keyword(s):  
Ross Sea ◽  
Crystal Nucleation ◽  
Ice Crystal ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Notothenioid Fish ◽  
Equilibrium Melting Point ◽  
Anchor Ice ◽  
Near Shore

We obtained two years (1999–2001) of continuous, high resolution temperature and pressure data at two near-shore shallow water sites in McMurdo Sound, Ross Sea. Contrary to the long-held assumption of constant freezing conditions in the Sound, these records revealed dynamic temperature fluctuations and substantial warming during January to March reaching peak water temperatures of about −0.5°C. They also revealed that excursions above −1.1°C, the equilibrium melting point of ice in Antarctic notothenioid fish, totalled 8–21 days during the summer. Microscopic ice crystals are known to enter these fish but ice growth is arrested by antifreeze proteins. Prior to this study there were no known mechanisms of eliminating accumulated endogenous ice. The warm temperature excursions provide for the first time a possible physical mechanism, passive melting, for ice removal. The continuous records also showed a correlation between tidal pressures and cold temperature episodes, which suggests the influx of cold currents from under the Ross Ice Shelf may provide a mechanism for ice crystal nucleation as the source of the ice in McMurdo Sound fish. The accumulation of anchor ice on one logger caused it to float up which was recorded as a decrease in pressure. This is the first evidence for the time of onset of anchor ice formation in McMurdo Sound.

scholarly journals Movement of the Ross Ice Shelf Near Scott Base

1961 ◽  
Vol 3 (29) ◽  
pp. 859-866 ◽  
Author(s):  
W. J. P. Macdonald ◽  
T. Hatherton
Keyword(s):  
Ross Sea ◽  
Average Rate ◽  
The South ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Rate Of Movement

Abstract The rate of movement of the Ross Ice Shelf has been determined at its terminal face to the south-east of Scott Base. An average rate of movement of 23 cm./day in a direction 270° True was determined for the period March 1957 to October 1958. The terminating face of the ice shelf in McMurdo Sound is only about 3 metres thick compared with a thickness of several hundred metres in the Ross Sea. Altimeter heights are used to demonstrate a thinning of the shelf which is attributed to melting from below.

scholarly journals Beaches in McMurdo Sound, Antarctica

2021 ◽  
Author(s):  
◽  
Edward R T Butler
Keyword(s):  
Ross Sea ◽  
Wave Climate ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Local Wave ◽  
Western Side ◽  
Sand And Gravel ◽  
A Site ◽  
Raised Beaches

<p>Modern beaches in McMurdo Sound can be divided into 3 process regimes. Beaches on Ross Island (eastern McMurdo Sound) are characterised by marine processes with little ice modification. On ice-bound western McMurdo Sound, coastal orientation is of paramount importance. Ice thrust features are prominent on south facing beaches, which are open to the predominant wind direction and receive relatively small waves from the fetch restricted south. A greater degree of marine dominance is exhibited by beaches on north facing coasts where sea ice is blown offshore and the beaches are open to the larger storm waves from the eastern Ross Sea. The single most useful indicator of the relative importance of marine and ice processes on the beaches is the roundness of the beach material. Unlike the modern beaches, raised beach ridges at all sites comprise poorly sorted cobbles in a mixed sand and gravel matrix. These are inferred to be storm ridges. In contrast with the raised beaches, the modern beaches on the western side of the Sound have evidence of ice processes on them. This suggests that the modem beach has not experienced the same magnitude storms that produced the raised beaches. The size and frequency of the ridges is a product of the local wave climate. The number of raised beaches at any site is a useful indicator of the paleo-wave climate. More ridges occur in sheltered south facing locations, because they are more protected from open marine conditions, than on beaches in ice-free or north facing locations. When determining the marine limit of a site the most useful features are, low energy marine bedding features (such as flaser bedding) and boulder pavements. Based on inferred process information at the time of deposition, revised estimates of marine limits in McMurdo Sound and a new marine limit at Cape Barne are presented. Because the nature of the raised beaches has not been fully considered by previous authors sea level curves are inaccurate. The reconstruction of the retreat of the Ross Ice Shelf from marine limits in McMurdo Sound shows a three stage stepwise southward retreat of the Ross Ice Shelf. A breakout from somewhere north of Cape Roberts and south of Cape Ross back to Marble Point (on the western side of the Sound) while remaining north of Cape Bird (on the eastern side of the Sound), occurred sometime around 8,000 years ago. Another breakout cleared ice from Cape Bird to somewhere south of Cape Barne and south of Cape Bernacchi around 5,000 years ago. This differs with other authors work (Hall and Denton, 1999, Kellogg et al., 1996, Stuiver et al., 1981) by suggesting a considerably older date for the Ross Ice Sheet retreating from McMurdo Sound. The data presented here suggests that much of McMurdo Sound was ice free about 1,500 years before earlier estimates at about 6,500 years. The effect of the change in deglaciation timing is to reduce isostatic rebound rates. This suggests that there was less ice in McMurdo Sound during the Last Glacial Maximum.</p>

scholarly journals Movement of the Ross Ice Shelf Near Scott Base

1961 ◽  
Vol 3 (29) ◽  
pp. 859-866
Author(s):  
W. J. P. Macdonald ◽  
T. Hatherton
Keyword(s):  
Ross Sea ◽  
Average Rate ◽  
The South ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Rate Of Movement

AbstractThe rate of movement of the Ross Ice Shelf has been determined at its terminal face to the south-east of Scott Base. An average rate of movement of 23 cm./day in a direction 270° True was determined for the period March 1957 to October 1958. The terminating face of the ice shelf in McMurdo Sound is only about 3 metres thick compared with a thickness of several hundred metres in the Ross Sea. Altimeter heights are used to demonstrate a thinning of the shelf which is attributed to melting from below.

scholarly journals Late Pleistocene interactions of East and West Antarctic Ice-flow Regimes: evidence from the McMurdo Ice Shelf

1996 ◽  
Vol 42 (142) ◽  
pp. 486-500 ◽  
Author(s):  
Thomas B. Kellogg ◽  
Terry Hughes ◽  
Davida E. Kellogg
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Grounding Line ◽  
Glacier Ice ◽  
East And West

AbstractWe present new interpretations of deglaciation in McMurdo Sound and the western Ross Sea, with observationally based reconstructions of interactions between East and West Antarctic ice at the last glacial maximum (LGM), 16000, 12000, 8000 and 4000 BP. At the LGM, East Antarctic ice from Mulock Glacier split; one branch turned westward south of Ross Island but the other branch rounded Ross Island before flowing southwest into McMurdo Sound. This flow regime, constrained by an ice saddle north of Ross Island, is consistent with the reconstruction of Stuiver and others (1981a). After the LGM, grounding-line retreat was most rapid in areas with greatest water depth, especially along the Victoria Land coast. By 12000 BP, the ice-now regime in McMurdo Sound changed to through-flowing Mulock Glacier ice, with lesser contributions from Koettlitz, Blue and Ferrar Glaciers, because the former ice saddle north of Ross Island was replaced by a dome. The modern flew regime was established ∼4000 BP. Ice derived from high elevations on the Polar Plateau but now stranded on the McMurdo Ice Shelf, and the pattern of the Transantarctic Mountains erratics support our reconstructions of Mulock Glacier ice rounding Minna Bluff but with all ice from Skelton Glacier ablating south of the bluff. They are inconsistent with Drewry’s (1979) LGM reconstruction that includes Skelton Glacier ice in the McMurdo-Sound through-flow. Drewry’s (1979) model closely approximates our results for 12000-4000 BP. Ice-sheet modeling holds promise for determining whether deglaciation proceeded by grounding-line retreat of an ice sheet that was largely stagnant, because it never approached equilibrium flowline profiles after the Ross Ice Shelf grounded, or of a dynamic ice sheet with flowline profiles kept low by active ice streams that extended northward from present-day outlet glaciers after the Ross Ice Shelf grounded.

scholarly journals Late Wisconsin Reconstruction for the Ross Sea Region, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 231-244 ◽  
Author(s):  
David J. Drewry
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Ross Sea ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Level Lowering

AbstractIf sea-level depression in the Ross Sea embayment were: (1) &lt; 120–130 m, or (2) &gt; 120–130 m but sustained for &lt; 104a, it is unlikely that the Ross Ice Shelf would have become fully grounded over the whole continental shelf during Wisconsin times. Sediments flooring the Ross Sea and recent estimates of sea-level lowering and post-glacial emergence yield little support for grounded ice but do provide some evidence for expanded ice-shelf conditions. A reconstruction is presented based on this premise. The model is compatible with glacial geologic results, especially those in the McMurdo Sound area.

scholarly journals Late Wisconsin Reconstruction for the Ross Sea Region, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 231-244 ◽  
Author(s):  
David J. Drewry
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Ross Sea ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Level Lowering

AbstractIf sea-level depression in the Ross Sea embayment were: (1) < 120–130 m, or (2) > 120–130 m but sustained for < 104 a, it is unlikely that the Ross Ice Shelf would have become fully grounded over the whole continental shelf during Wisconsin times. Sediments flooring the Ross Sea and recent estimates of sea-level lowering and post-glacial emergence yield little support for grounded ice but do provide some evidence for expanded ice-shelf conditions. A reconstruction is presented based on this premise. The model is compatible with glacial geologic results, especially those in the McMurdo Sound area.

scholarly journals Beaches in McMurdo Sound, Antarctica

2021 ◽  
Author(s):  
◽  
Edward R T Butler
Keyword(s):  
Ross Sea ◽  
Wave Climate ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Local Wave ◽  
Western Side ◽  
Sand And Gravel ◽  
A Site ◽  
Raised Beaches

<p>Modern beaches in McMurdo Sound can be divided into 3 process regimes. Beaches on Ross Island (eastern McMurdo Sound) are characterised by marine processes with little ice modification. On ice-bound western McMurdo Sound, coastal orientation is of paramount importance. Ice thrust features are prominent on south facing beaches, which are open to the predominant wind direction and receive relatively small waves from the fetch restricted south. A greater degree of marine dominance is exhibited by beaches on north facing coasts where sea ice is blown offshore and the beaches are open to the larger storm waves from the eastern Ross Sea. The single most useful indicator of the relative importance of marine and ice processes on the beaches is the roundness of the beach material. Unlike the modern beaches, raised beach ridges at all sites comprise poorly sorted cobbles in a mixed sand and gravel matrix. These are inferred to be storm ridges. In contrast with the raised beaches, the modern beaches on the western side of the Sound have evidence of ice processes on them. This suggests that the modem beach has not experienced the same magnitude storms that produced the raised beaches. The size and frequency of the ridges is a product of the local wave climate. The number of raised beaches at any site is a useful indicator of the paleo-wave climate. More ridges occur in sheltered south facing locations, because they are more protected from open marine conditions, than on beaches in ice-free or north facing locations. When determining the marine limit of a site the most useful features are, low energy marine bedding features (such as flaser bedding) and boulder pavements. Based on inferred process information at the time of deposition, revised estimates of marine limits in McMurdo Sound and a new marine limit at Cape Barne are presented. Because the nature of the raised beaches has not been fully considered by previous authors sea level curves are inaccurate. The reconstruction of the retreat of the Ross Ice Shelf from marine limits in McMurdo Sound shows a three stage stepwise southward retreat of the Ross Ice Shelf. A breakout from somewhere north of Cape Roberts and south of Cape Ross back to Marble Point (on the western side of the Sound) while remaining north of Cape Bird (on the eastern side of the Sound), occurred sometime around 8,000 years ago. Another breakout cleared ice from Cape Bird to somewhere south of Cape Barne and south of Cape Bernacchi around 5,000 years ago. This differs with other authors work (Hall and Denton, 1999, Kellogg et al., 1996, Stuiver et al., 1981) by suggesting a considerably older date for the Ross Ice Sheet retreating from McMurdo Sound. The data presented here suggests that much of McMurdo Sound was ice free about 1,500 years before earlier estimates at about 6,500 years. The effect of the change in deglaciation timing is to reduce isostatic rebound rates. This suggests that there was less ice in McMurdo Sound during the Last Glacial Maximum.</p>

scholarly journals Late Pleistocene interactions of East and West Antarctic Ice-flow Regimes: evidence from the McMurdo Ice Shelf

1996 ◽  
Vol 42 (142) ◽  
pp. 486-500
Author(s):  
Thomas B. Kellogg ◽  
Terry Hughes ◽  
Davida E. Kellogg
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Grounding Line ◽  
Glacier Ice ◽  
East And West

AbstractWe present new interpretations of deglaciation in McMurdo Sound and the western Ross Sea, with observationally based reconstructions of interactions between East and West Antarctic ice at the last glacial maximum (LGM), 16000, 12000, 8000 and 4000 BP. At the LGM, East Antarctic ice from Mulock Glacier split; one branch turned westward south of Ross Island but the other branch rounded Ross Island before flowing southwest into McMurdo Sound. This flow regime, constrained by an ice saddle north of Ross Island, is consistent with the reconstruction of Stuiver and others (1981a). After the LGM, grounding-line retreat was most rapid in areas with greatest water depth, especially along the Victoria Land coast. By 12000 BP, the ice-now regime in McMurdo Sound changed to through-flowing Mulock Glacier ice, with lesser contributions from Koettlitz, Blue and Ferrar Glaciers, because the former ice saddle north of Ross Island was replaced by a dome. The modern flew regime was established ∼4000 BP. Ice derived from high elevations on the Polar Plateau but now stranded on the McMurdo Ice Shelf, and the pattern of the Transantarctic Mountains erratics support our reconstructions of Mulock Glacier ice rounding Minna Bluff but with all ice from Skelton Glacier ablating south of the bluff. They are inconsistent with Drewry’s (1979) LGM reconstruction that includes Skelton Glacier ice in the McMurdo-Sound through-flow. Drewry’s (1979) model closely approximates our results for 12000-4000 BP. Ice-sheet modeling holds promise for determining whether deglaciation proceeded by grounding-line retreat of an ice sheet that was largely stagnant, because it never approached equilibrium flowline profiles after the Ross Ice Shelf grounded, or of a dynamic ice sheet with flowline profiles kept low by active ice streams that extended northward from present-day outlet glaciers after the Ross Ice Shelf grounded.

Iceberg-induced changes to polynya operation and regional oceanography in the southern Ross Sea, Antarctica, from in situ observations

2012 ◽  
Vol 24 (5) ◽  
pp. 514-526 ◽  
Author(s):  
N.J. Robinson ◽  
M.J.M. Williams
Keyword(s):  
Water Column ◽  
Ross Sea ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
Dense Water ◽  
Modelling Studies ◽  
Polar Ocean ◽  
Ocean Processes

AbstractTwo massive tabular icebergs calved from the Ross Ice Shelf in 2000 (B-15) and 2002 (C-19) and perturbed regional ocean processes for several years. Here we document the ocean's response in McMurdo Sound to the icebergs using in situ data collected before, during and after the icebergs’ residence in the Ross Sea. Departures from typical McMurdo Sound seasonal oceanography included the non-appearance of Antarctic Surface Water in summer, a cooler and more homogeneous water column during winter and ‘super-fresh’ High Salinity Shelf Water that gradually recovered its salinity. We found that each iceberg triggered a distinct response to regional ocean processes. B-15a, the largest piece of iceberg B-15, restricted surface circulation, cooled and freshened the upper water column and reduced melting near the ice shelf front for four years. Iceberg C-19 interrupted the operation of the Ross Sea polynya, from which McMurdo Sound took three to four years to recover, and was responsible for a geographic shift in the dense water formation region for the south-western Ross Sea. These results differ from earlier modelling studies and highlight the challenges of modelling the polar ocean. We also show that one pathway previously thought to supply dense water to the Ross Ice Shelf cavity was not operating at that time.

scholarly journals Environmental and Oceanographic Conditions at the Continental Margin of the Central Basin, Northwestern Ross Sea (Antarctica) Since the Last Glacial Maximum

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 155
Author(s):  
Fiorenza Torricella ◽  
Romana Melis ◽  
Elisa Malinverno ◽  
Giorgio Fontolan ◽  
Mauro Bussi ◽  
...  
Keyword(s):  
Continental Margin ◽  
Ross Sea ◽  
Time Interval ◽  
Central Basin ◽  
Ice Shelf ◽  
Last Glacial ◽  
Ross Ice Shelf ◽  
Sedimentary Sequences ◽  
Ash Layer ◽  
The Last Glacial

The continental margin is a key area for studying the sedimentary processes related to the advance and retreat of the Ross Ice Shelf (Antarctica); nevertheless, much remains to be investigated. The aim of this study is to increase the knowledge of the last glacial/deglacial dynamics in the Central Basin slope–basin system using a multidisciplinary approach, including integrated sedimentological, micropaleontological and tephrochronological information. The analyses carried out on three box cores highlighted sedimentary sequences characterised by tree stratigraphic units. Collected sediments represent a time interval from 24 ka Before Present (BP) to the present time. Grain size clustering and data on the sortable silt component, together with diatom, silicoflagellate and foraminifera assemblages indicate the influence of the ice shelf calving zone (Unit 1, 24–17 ka BP), progressive receding due to Circumpolar Deep Water inflow (Unit 2, 17–10.2 ka BP) and (Unit 3, 10.2 ka BP–present) the establishment of seasonal sea ice with a strengthening of bottom currents. The dominant and persistent process is a sedimentation controlled by contour currents, which tend to modulate intensity in time and space. A primary volcanic ash layer dated back at around 22 ka BP is correlated with the explosive activity of Mount Rittmann.

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