Preliminary observations from long-term current meter moorings near the Ross Ice Shelf, Antarctica

1985 ◽  
pp. 87-107 ◽  
Author(s):  
R. Dale Pillsbury ◽  
Stanley S. Jacobs
Keyword(s):  
Ice Shelf ◽  
Ross Ice Shelf

scholarly journals The supply of subglacial meltwater to the grounding line of the Siple Coast, West Antarctica

2012 ◽  
Vol 53 (60) ◽  
pp. 267-280 ◽  
Author(s):  
S.P. Carter ◽  
H.A. Fricker
Keyword(s):  
Temporal Variability ◽  
Freshwater Flux ◽  
Spatial And Temporal Variability ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ross Ice Shelf ◽  
Lake Volume ◽  
Grounding Line ◽  
Subglacial Lakes

AbstractRecent satellite studies have shown that active subglacial lakes exist under the Antarctic ice streams and persist almost to their grounding lines. When the lowest-lying lakes flood, the water crosses the grounding line and enters the sub-ice-shelf cavity. Modeling results suggest that this additional freshwater influx may significantly enhance melting at the ice-shelf base. We examine the spatial and temporal variability in subglacial water supply to the grounding lines of the Siple Coast ice streams, by combining estimates for lake volume change derived from Ice, Cloud and land Elevation Satellite (ICESat) data with a model for subglacial water transport. Our results suggest that subglacial outflow tends to concentrate towards six embayments in the Siple Coast grounding line. Although mean grounding line outflow is ~60m3 s–1 for the entire Siple Coast, maximum local grounding line outflow may temporarily exceed 300 m3 s–1 during the synchronized flooding of multiple lakes in a hydrologic basin. Variability in subglacial outflow due to subglacial lake drainage may account for a substantial portion of the observed variability in freshwater flux out of the Ross Ice Shelf cavity. The temporal variability in grounding line outflow results in a net reduction in long-term average melt rate, but temporary peak melting rates may exceed the long-term average by a factor of three.

scholarly journals Using distributed temperature sensors to monitor an Antarctic ice shelf and sub-ice-shelf cavity

2013 ◽  
Vol 59 (215) ◽  
pp. 583-591 ◽  
Author(s):  
S.W. Tyler ◽  
D.M. Holland ◽  
V. Zagorodnov ◽  
A.A. Stern ◽  
C. Sladek ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Monitoring Methods ◽  
Distributed Temperature Sensing ◽  
Ice Shelf ◽  
Term Operation ◽  
Ross Ice Shelf ◽  
Surface Data ◽  
Distributed Temperature Sensors ◽  
Fiber Optic Temperature

AbstractMonitoring of ice-shelf and sub-ice-shelf ocean temperatures represents an important component in understanding ice-sheet stability. Continuous monitoring is challenging due to difficult surface access, difficulties in penetrating the ice shelf, and the need for long-term operation of non-recoverable sensors. We aim to develop rapid lightweight drilling and near-continuous fiber-optic temperature-monitoring methods to meet these challenges. During November 2011, two instrumented moorings were installed within and below the McMurdo Ice Shelf (a sub-region of the Ross Ice Shelf, Antarctica) at Windless Bight. We used a combination of ice coring for the upper portion of each shelf borehole and hot-point drilling for penetration into the ocean. The boreholes provided temporary access to the ice-shelf cavity, into which distributed temperature sensing (DTS) fiber-optic cables and conventional pressure/temperature transducers were installed. The DTS moorings provided near-continuous (in time and depth) observations of ice and ocean temperatures to a depth of almost 800 m beneath the ice-shelf surface. Data received document the presence of near-freezing water throughout the cavity from November through January, followed by an influx of warmer water reaching ∼150 m beneath the ice-shelf base during February and March. The observations demonstrate prospects for achieving much higher spatial sampling of temperature than more conventional oceanographic moorings.

Some dynamics of water outflow from beneath the Ross Ice Shelf during 1995 and 1996

2002 ◽  
Vol 14 (1) ◽  
pp. 74-82 ◽  
Author(s):  
A. Bergamasco ◽  
V. Defendi ◽  
R. Meloni
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Sediment Traps ◽  
Shelf Water ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Current Profiler ◽  
Antarctic Research ◽  
Ice Shelf Water ◽  
Water Outflow

The paper presents two years of observations (1995 and 1996) for water velocity and temperature near the Ross Ice Shelf edge, where a mooring, composed of three current meters, five temperature and three conductivity sensors, one turbidimeter, two sediment traps and one Acoustic Doppler Current Profiler, was deployed. The mooring site was chosen to study the behaviour of the Ice Shelf Water, within the framework of the Project on the Climatic Long-term Interaction for the Mass balance in Antarctica of the Italian National Programme for Antarctic Research. The Ice Shelf Water outflow from below the Ross Ice Shelf is a persistent phenomenon in this area, but it is characterized by impulsive injections often associated with recirculation processes. Two years of data records of physical variables are investigated here in order to analyse the Ice Shelf Water outflow behaviour and to give an estimate of this feature. Our results show that the Ice Shelf Water events have variable duration (from one to seven days) and present an interannual variability in their timing. In spite of this, the mean Ice Shelf Water outflow during the overlapping period of the two time series is quite similar: 0.15 Sv for 1995 and 0.28 Sv for 1996.

scholarly journals A ground-based radar for measuring vertical strain rates and time-varying basal melt rates in ice sheets and shelves

2015 ◽  
Vol 61 (230) ◽  
pp. 1079-1087 ◽  
Author(s):  
Keith W. Nicholls ◽  
Hugh F.J. Corr ◽  
Craig L. Stewart ◽  
Lai Bun Lok ◽  
Paul V. Brennan ◽  
...  
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Present System ◽  
Strain Rates ◽  
Time Varying ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Vertical Strain ◽  
Phase Sensitive

AbstractThe ApRES (autonomous phase-sensitive radio-echo sounder) instrument is a robust, lightweight and relatively inexpensive radar that has been designed to allow long-term, unattended monitoring of ice-shelf and ice-sheet thinning. We describe the instrument and demonstrate its capabilities and limitations by presenting results from three trial campaigns conducted in different Antarctic settings. Two campaigns were ice sheet-based – Pine Island Glacier and Dome C – and one was conducted on the Ross Ice Shelf. The ice-shelf site demonstrates the ability of the instrument to collect a time series of basal melt rates; the two grounded ice applications show the potential to recover profiles of vertical strain rate and also demonstrate some of the limitations of the present system.

scholarly journals Ice Stream Slowdown Will Drive Long-Term Thinning of the Ross Ice Shelf, With or Without Ocean Warming

2018 ◽  
Vol 45 (1) ◽  
pp. 201-206 ◽  
Author(s):  
Adam J. Campbell ◽  
Christina L. Hulbe ◽  
Choon-Ki Lee
Keyword(s):  
Ocean Warming ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Ice Stream

scholarly journals Tidal and spatial variability of flow speed and seismicity near the grounding zone of Beardmore Glacier, Antarctica

2019 ◽  
Vol 60 (79) ◽  
pp. 37-44
Author(s):  
Jade Cooley ◽  
Paul Winberry ◽  
Michelle Koutnik ◽  
Howard Conway
Keyword(s):  
Seismic Activity ◽  
Flow Speed ◽  
Ice Shelf ◽  
Flow Paths ◽  
South Side ◽  
Ross Ice Shelf ◽  
North Side ◽  
Grounding Line ◽  
Horizontal Strain

ABSTRACTGPS measurements of tidal modulation of ice flow and seismicity within the grounding zone of Beardmore Glacier show that tidally induced fluctuations of horizontal flow are largest near the grounding line and decrease downstream. Seismic activity is continuous, but peaks occur on falling and rising tides. Beamforming methods reveal that most seismic events originate from two distinct locations, one on the grid-north side of the grounding zone, and one on the grid-south side. The broad pattern of deformation generated as Beardmore Glacier merges with the Ross Ice Shelf results in net extension along the grid-north side of the grounding zone and net compression along the grid-south side. During falling tides, seismic activity peaks on both sides because of increased vertical flexure across the grounding line. During rising tides, seismic activity in the region of extension on the grid-north side is relatively low because the tidal influence on both horizontal strain rate and vertical flexure is small. On the grid-south side during rising tides, however, tidally induced horizontal strain rates promote increased seismicity in regions of long-term compressional flow paths. Our study highlights how concurrent geodetic and seismic measurements provide insight into grounding-zone mechanics and their influence on ice-shelf buttressing.

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.

New determinations of tides on the north-western Ross Ice Shelf

2020 ◽  
pp. 1-14
Author(s):  
Richard D. Ray ◽  
Kristine M. Larson ◽  
Bruce J. Haines
Keyword(s):  
Time Series ◽  
Tide Gauge ◽  
High Rate ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Global Positioning ◽  
North Western

Abstract New determinations of ocean tides are extracted from high-rate Global Positioning System (GPS) solutions at nine stations sitting on the Ross Ice Shelf. Five are multi-year time series. Three older time series are only 2–3 weeks long. These are not ideal, but they are still useful because they provide the only in situ tide observations in that sector of the ice shelf. The long tide-gauge observations from Scott Base and Cape Roberts are also reanalysed. They allow determination of some previously neglected tidal phenomena in this region, such as third-degree tides, and they provide context for analysis of the shorter datasets. The semidiurnal tides are small at all sites, yet M2 undergoes a clear seasonal cycle, which was first noted by Sir George Darwin while studying measurements from the Discovery expedition. Darwin saw a much larger modulation than we observe, and we consider possible explanations - instrumental or climatic - for this difference.

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