An optimized estimate of glacial melt from the Ross Ice Shelf using noble gases, stable isotopes, and CFC transient tracers

2009 ◽  
Vol 114 (C8) ◽  
Author(s):  
B. Loose ◽  
P. Schlosser ◽  
W. M. Smethie ◽  
S. Jacobs
Keyword(s):  
Stable Isotopes ◽  
Noble Gases ◽  
Ice Shelf ◽  
Ross Ice Shelf

scholarly journals Atmospheric variability and precipitation in the Ross Sea region, Antarctica

2021 ◽  
Author(s):  
◽  
Lana Cohen
Keyword(s):  
Stable Isotopes ◽  
Isotopic Composition ◽  
Ross Sea ◽  
Isotope Composition ◽  
Ice Cores ◽  
Atmospheric Variability ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The Pacific ◽  
Climate Proxies

<p>Understanding how atmospheric variability in the Pacific sector of Antarctica drives precipitation is essential for understanding current and past climate changes on the West Antarctic Ice Sheet and the Ross Ice Shelf. Precipitation plays a key role in the Antarctic climate system (via mass balance of ice sheets) and is necessary for understanding past climates (via snow and ice proxies). However precipitation is difficult to measure and model and its variability in these regions is still not well understood. This thesis compiles three separate but inter-related studies which provide further understanding of the atmospheric variability of the Ross Sea region and its role in driving precipitation.   Synoptic classifications over the Southern Ocean in the Pacific sector of Antarctica (50°S–Antarctic coast, 150°E–90°W) are derived from NCEP reanalysis data (1979–2011), producing a set of six synoptic types for the region. These six types describe the atmospheric variability of the Ross and Amundsen Seas region for the past 33 years and show how hemispheric scale circulation patterns such as the El Niño-Southern Oscillation and the Southern Annular Mode are reflected in local precipitation and temperature on the Ross Ice Shelf. The synoptic types also provide understanding of how different source regions and transport pathways can influence precipitation on the Ross Ice Shelf, which is important for the interpretation of climate proxies.   Because of the sparseness of in-situ meteorological measurements in Antarctica, many studies (including the two described above) rely on atmospheric reanalyses data. However, assessments of reanalyses precipitation have only been done on annual and longer timescales. An assessment of the ERA-Interim and NCEP-2 reanalyses precipitation data on synoptic timescales is developed using statistical, event-based analysis of snow accumulation data from automatic weather stations around the Ross Ice Shelf. The results show that there are important differences between the two reanalyses products and that ERA-Interim represents precipitation better than NCEP-2 for this region.   Stable isotopes in snow (δ¹⁸O and δD) are widely used as temperature proxies, but are also influenced by moisture history, source region conditions, and cloud micro-physical processes. Further understanding of the relative importance of these other factors is provided by modeling the isotopic composition of snow at Roosevelt Island, an ice core site on the Ross Ice Shelf. A Rayleigh fractionation model is used to determine isotope composition on sub-storm (hourly) timescales, and the results are compared to measured isotope composition. The model is able to reproduce the significant variability of measured isotopes and shows the importance of air-mass mixing and moisture trajectories on the isotopic composition of snow at Roosevelt Island.   Together, these studies show how synoptic variability influences precipitation on the Ross Ice Shelf and at Roosevelt Island in particular, and they provide a basis for interpreting stable isotopes and other precipitation-based climate proxies in ice cores from the Roosevelt Island site.</p>

scholarly journals Atmospheric variability and precipitation in the Ross Sea region, Antarctica

2021 ◽  
Author(s):  
◽  
Lana Cohen
Keyword(s):  
Stable Isotopes ◽  
Isotopic Composition ◽  
Ross Sea ◽  
Isotope Composition ◽  
Ice Cores ◽  
Atmospheric Variability ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The Pacific ◽  
Climate Proxies

<p>Understanding how atmospheric variability in the Pacific sector of Antarctica drives precipitation is essential for understanding current and past climate changes on the West Antarctic Ice Sheet and the Ross Ice Shelf. Precipitation plays a key role in the Antarctic climate system (via mass balance of ice sheets) and is necessary for understanding past climates (via snow and ice proxies). However precipitation is difficult to measure and model and its variability in these regions is still not well understood. This thesis compiles three separate but inter-related studies which provide further understanding of the atmospheric variability of the Ross Sea region and its role in driving precipitation.   Synoptic classifications over the Southern Ocean in the Pacific sector of Antarctica (50°S–Antarctic coast, 150°E–90°W) are derived from NCEP reanalysis data (1979–2011), producing a set of six synoptic types for the region. These six types describe the atmospheric variability of the Ross and Amundsen Seas region for the past 33 years and show how hemispheric scale circulation patterns such as the El Niño-Southern Oscillation and the Southern Annular Mode are reflected in local precipitation and temperature on the Ross Ice Shelf. The synoptic types also provide understanding of how different source regions and transport pathways can influence precipitation on the Ross Ice Shelf, which is important for the interpretation of climate proxies.   Because of the sparseness of in-situ meteorological measurements in Antarctica, many studies (including the two described above) rely on atmospheric reanalyses data. However, assessments of reanalyses precipitation have only been done on annual and longer timescales. An assessment of the ERA-Interim and NCEP-2 reanalyses precipitation data on synoptic timescales is developed using statistical, event-based analysis of snow accumulation data from automatic weather stations around the Ross Ice Shelf. The results show that there are important differences between the two reanalyses products and that ERA-Interim represents precipitation better than NCEP-2 for this region.   Stable isotopes in snow (δ¹⁸O and δD) are widely used as temperature proxies, but are also influenced by moisture history, source region conditions, and cloud micro-physical processes. Further understanding of the relative importance of these other factors is provided by modeling the isotopic composition of snow at Roosevelt Island, an ice core site on the Ross Ice Shelf. A Rayleigh fractionation model is used to determine isotope composition on sub-storm (hourly) timescales, and the results are compared to measured isotope composition. The model is able to reproduce the significant variability of measured isotopes and shows the importance of air-mass mixing and moisture trajectories on the isotopic composition of snow at Roosevelt Island.   Together, these studies show how synoptic variability influences precipitation on the Ross Ice Shelf and at Roosevelt Island in particular, and they provide a basis for interpreting stable isotopes and other precipitation-based climate proxies in ice cores from the Roosevelt Island site.</p>

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.

scholarly journals Ross Ice Shelf airstream driven by polar vortex cyclone

Eos ◽  
2012 ◽  
Vol 93 (27) ◽  
pp. 256-256
Author(s):  
Colin Schultz
Keyword(s):  
Polar Vortex ◽  
Ice Shelf ◽  
Ross Ice Shelf

Ross Ice Shelf temperatures support a history of ice-shelf thickening

Nature ◽  
1979 ◽  
Vol 282 (5740) ◽  
pp. 703-705 ◽  
Author(s):  
Douglas R. MacAyeal ◽  
Robert H. Thomas
Keyword(s):  
Ice Shelf ◽  
Ross Ice Shelf ◽  
History Of

scholarly journals High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica

2016 ◽  
Vol 43 (1) ◽  
pp. 250-255 ◽  
Author(s):  
Oliver J. Marsh ◽  
Helen A. Fricker ◽  
Matthew R. Siegfried ◽  
Knut Christianson ◽  
Keith W. Nicholls ◽  
...  
Keyword(s):  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Grounding Line ◽  
Basal Melting

Ground-penetrating radar profiles of the McMurdo Shear Zone, Antarctica, acquired with an unmanned rover: Interpretation of crevasses, fractures, and folds within firn and marine ice

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA21-WA34 ◽  
Author(s):  
Steven A. Arcone ◽  
James H. Lever ◽  
Laura E. Ray ◽  
Benjamin S. Walker ◽  
Gordon Hamilton ◽  
...  
Keyword(s):  
Shear Zone ◽  
Ground Penetrating Radar ◽  
Ice Accretion ◽  
Ice Shelf ◽  
Ice Flow ◽  
Ross Ice Shelf ◽  
Robotic Vehicle ◽  
Ground Penetrating ◽  
Depth Ranges ◽  
Radar Antennas

The crevassed firn of the McMurdo shear zone (SZ) within the Ross Ice Shelf may also contain crevasses deep within its meteoric and marine ice, but the surface crevassing prevents ordinary vehicle access to investigate its structure geophysically. We used a lightweight robotic vehicle to tow 200- and 400-MHz ground-penetrating radar antennas simultaneously along 100 parallel transects over a [Formula: see text] grid spanning the SZ width. Transects were generally orthogonal to the ice flow. Total firn and meteoric ice thickness was approximately 160 m. Firn crevasses profiled at 400 MHz were up to 16 m wide, under snow bridges up to 10 m thick, and with strikes near 35°–40° to the transect direction. From the top down, 200-MHz profiles revealed firn diffractions originating to a depth of approximately 40 m, no discernible structure within the meteoric ice, a discontinuous transitional horizon, and at least 20 m of stratified marine ice; 28–31 m of freeboard found more marine ice exists. Based on 10 consecutive transects covering approximately [Formula: see text], we preliminarily interpreted the transitional horizon to be a thin saline layer, and marine ice hyperbolic diffractions and reflections to be responses to localized fractures, and crevasses filled with unstratified marine ice, all at strikes from 27° to 50°. We preliminarily interpreted off-nadir, marine ice horizons to be responses to linear and folded faults, similar to some in firn. The coinciding and synchronously folded areas of fractured firn and marine ice suggested that the visibly unstructured meteoric ice beneath our grid was also fractured, but either never crevassed, crevassed and sutured without marine ice inclusions, or that any ice containing crevasses might have eroded before marine ice accretion. We will test these interpretations with analysis of all transects and by extending our grid and increasing our depth ranges.

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