scholarly journals Response of the Ross Ice Shelf, Antarctica, to ocean gravity-wave forcing

2012 ◽  
Vol 53 (60) ◽  
pp. 163-172 ◽  
Author(s):  
Peter D. Bromirski ◽  
Ralph A. Stephen
Keyword(s):  
Sea Ice ◽  
Gravity Wave ◽  
Seismic Station ◽  
Wind Waves ◽  
Signal Propagation ◽  
Spectral Peak ◽  
Dry Valleys ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Wave Forcing

AbstractComparison of the Ross Ice Shelf (RIS, Antarctica) response at near-front seismic station RIS2 with seismometer data collected on tabular iceberg B15A and with land-based seismic stations at Scott Base on Ross Island (SBA) and near Lake Vanda in the Dry Valleys (VNDA) allows identification of RIS-specific signals resulting from gravity-wave forcing that includes meteorologically driven wind waves and swell, infragravity (IG) waves and tsunami waves. The vibration response of the RIS varies with season and with the frequency and amplitude of the gravity-wave forcing. The response of the RIS to IG wave and swell impacts is much greater than that observed at SBA and VNDA. A spectral peak at near-ice-front seismic station RIS2 centered near 0.5 Hz, which persists during April when swell is damped by sea ice, may be a dominant resonance or eigenfrequency of the RIS. High-amplitude swell events excite relatively broadband signals that are likely fracture events (icequakes). Changes in coherence between the vertical and horizontal sensors in the 8–12 Hz band from February to April, combined with the appearance of a spectral peak near 10 Hz in April when sea ice damps swell, suggest that lower (higher) temperatures during austral winter (summer) months affect signal propagation characteristics and hence mechanical properties of the RIS.

scholarly journals Modeling the effect of Ross Ice Shelf melting on the Southern Ocean in quasi-equilibrium

2018 ◽  
Vol 12 (9) ◽  
pp. 3033-3044 ◽  
Author(s):  
Xiying Liu
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ross Sea ◽  
Global Ocean ◽  
Freshwater Flux ◽  
Quasi Equilibrium ◽  
Ice Shelf ◽  
Sea Ice Concentration ◽  
Ross Ice Shelf ◽  
Ice Concentration

Abstract. To study the influence of basal melting of the Ross Ice Shelf (BMRIS) on the Southern Ocean (ocean southward of 35∘ S) in quasi-equilibrium, numerical experiments with and without the BMRIS effect were performed using a global ocean–sea ice–ice shelf coupled model. In both experiments, the model started from a state of quasi-equilibrium ocean and was integrated for 500 years forced by CORE (Coordinated Ocean-ice Reference Experiment) normal-year atmospheric fields. The simulation results of the last 100 years were analyzed. The melt rate averaged over the entire Ross Ice Shelf is 0.25 m a−1, which is associated with a freshwater flux of 3.15 mSv (1 mSv = 103 m3 s−1). The extra freshwater flux decreases the salinity in the region from 1500 m depth to the sea floor in the southern Pacific and Indian oceans, with a maximum difference of nearly 0.005 PSU in the Pacific Ocean. Conversely, the effect of concurrent heat flux is mainly confined to the middle depth layer (approximately 1500 to 3000 m). The decreased density due to the BMRIS effect, together with the influence of ocean topography, creates local differences in circulation in the Ross Sea and nearby waters. Through advection by the Antarctic Circumpolar Current, the flux difference from BMRIS gives rise to an increase of sea ice thickness and sea ice concentration in the Ross Sea adjacent to the coast and ocean water to the east. Warm advection and accumulation of warm water associated with differences in local circulation decrease sea ice concentration on the margins of sea ice cover adjacent to open water in the Ross Sea in September. The decreased water density weakens the subpolar cell as well as the lower cell in the global residual meridional overturning circulation (MOC). Moreover, we observe accompanying reduced southward meridional heat transport at most latitudes of the Southern Ocean.

scholarly journals Ice Movement Studies on the Skelton Glacier

1961 ◽  
Vol 3 (29) ◽  
pp. 873-878
Author(s):  
Charles R. Wilson ◽  
A. P. Crary
Keyword(s):  
Ross Sea ◽  
Ice Thickness ◽  
Strain Rates ◽  
Shelf Area ◽  
Dry Valleys ◽  
Ice Shelf ◽  
The West ◽  
Ross Ice Shelf ◽  
High Plateau ◽  
Plateau Area

The volume of ice that flows annually from the Skelton Glacier on the west side of the Ross Ice Shelf between the Worcester and Royal Society Ranges was determined during 1958–59 traverse operations to be approximately 791 × 106 m.3 or 712 × 106 m.3 water equivalent. Annual accumulation on the Skelton névé field and small cirque glaciers is estimated to be 1,018 × 106 m.3 water equivalent, but this figure can be reduced to 712 × 106 m.3 by assuming that 30 per cent of the expected accumulation in the lower slopes of the glacier is lost to adjacent areas of the Ross Ice Shelf by katabatic winds. It is evident that little or no contribution to the nourishment of the Skelton Glacier comes from the high plateau area of East Antarctica. It is suggested that this condition exists generally in the western Ross Sea and Ross Shelf area, and is responsible for the existence of the present “dry” valleys in the McMurdo Sound area.Some estimates of local ice regime are made at two sites on the glacier where ice thickness and strain rates are known.

scholarly journals Ross Ice Shelf Icequakes Associated With Ocean Gravity Wave Activity

2019 ◽  
Vol 46 (15) ◽  
pp. 8893-8902 ◽  
Author(s):  
Z. Chen ◽  
P. D. Bromirski ◽  
P. Gerstoft ◽  
R. A. Stephen ◽  
W. S. Lee ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Wave Activity ◽  
Ice Shelf ◽  
Ross Ice Shelf

scholarly journals Large Salt Beds on the Surface of the Ross Ice Shelf Near Black Island, Antarctica

1981 ◽  
Vol 27 (95) ◽  
pp. 11-18 ◽  
Author(s):  
Howard Thomas Brady ◽  
Barry Batts
Keyword(s):  
Thin Layer ◽  
Dry Valleys ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Extensive System ◽  
Ross Ice Shelf ◽  
Victoria Land ◽  
Marine Algal ◽  
Algal Mat

AbstractAn extensive system of mirabilite (Na2SO4· 10H2O) beds has been mapped on the Ross Ice Shelf near Black Island. The salt beds are normally underlain by a thin layer of mud and their surface is covered by a non-marine algal mat and boulder lag. These authors suggest the salt has been formed by the displacement of sub-ice-shelf brines to the ice-shelf surface. Evidence also suggests that other terrestrial mirabilite beds in the McMurdo Sound area were formed in the same manner and deposited by the Ross Ice Shelf during its Wisconsin retreat from McMurdo Sound. Mirabilite salt in the dry valleys, southern Victoria Land, may have also originated from melt waters which dissolved ice-shelf mirabilite beds.

scholarly journals Atmospheric forcing of sea ice anomalies in the Ross Sea polynya region

2017 ◽  
Vol 11 (1) ◽  
pp. 267-280 ◽  
Author(s):  
Ethan R. Dale ◽  
Adrian J. McDonald ◽  
Jack H. J. Coggins ◽  
Wolfgang Rack
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Strong Wind ◽  
Ice Shelf ◽  
Sea Ice Concentration ◽  
Ross Ice Shelf ◽  
Wind Speeds ◽  
Brightness Temperatures ◽  
Wind Event ◽  
Wind Events

Abstract. We investigate the impacts of strong wind events on the sea ice concentration within the Ross Sea polynya (RSP), which may have consequences on sea ice formation. Bootstrap sea ice concentration (SIC) measurements derived from satellite SSM/I brightness temperatures are correlated with surface winds and temperatures from Ross Ice Shelf automatic weather stations (AWSs) and weather models (ERA-Interim). Daily data in the austral winter period were used to classify characteristic weather regimes based on the percentiles of wind speed. For each regime a composite of a SIC anomaly was formed for the entire Ross Sea region and we found that persistent weak winds near the edge of the Ross Ice Shelf are generally associated with positive SIC anomalies in the Ross Sea polynya and vice versa. By analyzing sea ice motion vectors derived from the SSM/I brightness temperatures we find significant sea ice motion anomalies throughout the Ross Sea during strong wind events, which persist for several days after a strong wind event has ended. Strong, negative correlations are found between SIC and AWS wind speed within the RSP indicating that strong winds cause significant advection of sea ice in the region. We were able to partially recreate these correlations using colocated, modeled ERA-Interim wind speeds. However, large AWS and model differences are observed in the vicinity of Ross Island, where ERA-Interim underestimates wind speeds by a factor of 1.7 resulting in a significant misrepresentation of RSP processes in this area based on model data. Thus, the cross-correlation functions produced by compositing based on ERA-Interim wind speeds differed significantly from those produced with AWS wind speeds. In general the rapid decrease in SIC during a strong wind event is followed by a more gradual recovery in SIC. The SIC recovery continues over a time period greater than the average persistence of strong wind events and sea ice motion anomalies. This suggests that sea ice recovery occurs through thermodynamic rather than dynamic processes.

scholarly journals Modelling Ross Ice Shelf melting effect on the Southern Ocean in quasi-equilibrium

2017 ◽  
Author(s):  
Xiying Liu
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ross Sea ◽  
Global Ocean ◽  
Freshwater Flux ◽  
Quasi Equilibrium ◽  
Ice Shelf ◽  
Local Circulation ◽  
Sea Ice Concentration ◽  
Ross Ice Shelf

Abstract. To study the influence of basal melting of Ross Ice Shelf (BMR) on the Southern Ocean (ocean southward of 35° S) in quasi-equilibrium, numerical experiments with and without BMR effect have been performed with a global ocean-sea ice-ice shelf coupled model. In both experiments, the model started from a state of quasi-equilibrium ocean and was integrated for 500 years forced by CORE (Coordinated Ocean-ice Reference Experiment) normal year atmospheric fields. The simulation results of the last 100 years have been analysed. It’s shown that, the melt rate averaged over the entire Ross Ice Shelf is 0.253 m/a, which is associated with a freshwater flux of 3.15 mSv (1 mSv = 103 m3/s). The extra freshwater flux decreases the salinity in the Southern Ocean substantially whereas the effect of concurrent heat flux is not so significant except in the middle layer of water body (roughly from 1500 m to 3000 m). The decreased density due to BMR effect creates local circulation anomalies in the Ross Sea and nearby water with the help of ocean bathymetry. Through advection by the Antarctic Circumpolar Current, the flux anomaly from BMR gives rise to the increase of sea ice thickness and sea ice concentration in the Ross Sea adjacent to the coast and the ocean water westward. The warm advection and downwelling associated with the local circulation anomalies decrease the sea ice concentration in the rim of sea ice cover adjacent to open water in the Ross Sea in September. The decreased density weakens the sub-polar cell as well as the lower cell in the global residual meridional overturning circulation. And, northward meridional heat transport anomaly in most latitudes of the global ocean is accompanied accordingly.

scholarly journals ARIANNA: Current developments and understanding the ice for neutrino detection

2019 ◽  
Vol 216 ◽  
pp. 01008 ◽  
Author(s):  
Anna Nelles
Keyword(s):  
Signal Propagation ◽  
High Gain ◽  
Neutrino Interaction ◽  
Simulation Framework ◽  
Pilot Phase ◽  
Dipole Antennas ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Neutrino Detection ◽  
Radio Signals

The ARIANNA experiment aims to detect the radio signals of cosmogenic neutrinos. It is running in its pilot phase on the Ross Ice-shelf, and one station has been installed at South Pole. The ARIANNA concept is based on installing high-gain log periodic dipole antennas close to the surface monitoring the underlying ice for the radi signals following a neutrino interaction. Especially, but not only in this configuration, it is essential to understand the trajectories that the signals take through the ice. We will report on various experimental evidence concerning the signal propagation in ice. We will discuss the implications for neutrino detection, results of neutrino searches and give the first introduction to a new modular simulation framework.

scholarly journals Seasonal and spatial variations in the ocean-coupled ambient wavefield of the Ross Ice Shelf

2019 ◽  
Vol 65 (254) ◽  
pp. 912-925 ◽  
Author(s):  
Michael G. Baker ◽  
Richard C. Aster ◽  
Robert E. Anthony ◽  
Julien Chaput ◽  
Douglas A. Wiens ◽  
...  
Keyword(s):  
Sea Ice ◽  
Solid Earth ◽  
Spatial Variations ◽  
Horizontal Component ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Seasonal And Spatial Variations ◽  
Temporal And Spatial ◽  
Seismic Wavefield ◽  
Seismographic Network

AbstractThe Ross Ice Shelf (RIS) is host to a broadband, multimode seismic wavefield that is excited in response to atmospheric, oceanic and solid Earth source processes. A 34-station broadband seismographic network installed on the RIS from late 2014 through early 2017 produced continuous vibrational observations of Earth's largest ice shelf at both floating and grounded locations. We characterize temporal and spatial variations in broadband ambient wavefield power, with a focus on period bands associated with primary (10–20 s) and secondary (5–10 s) microseism signals, and an oceanic source process near the ice front (0.4–4.0 s). Horizontal component signals on floating stations overwhelmingly reflect oceanic excitations year-round due to near-complete isolation from solid Earth shear waves. The spectrum at all periods is shown to be strongly modulated by the concentration of sea ice near the ice shelf front. Contiguous and extensive sea ice damps ocean wave coupling sufficiently so that wintertime background levels can approach or surpass those of land-sited stations in Antarctica.

scholarly journals Large Salt Beds on the Surface of the Ross Ice Shelf Near Black Island, Antarctica

1981 ◽  
Vol 27 (95) ◽  
pp. 11-18
Author(s):  
Howard Thomas Brady ◽  
Barry Batts
Keyword(s):  
Thin Layer ◽  
Dry Valleys ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Extensive System ◽  
Ross Ice Shelf ◽  
Victoria Land ◽  
Marine Algal ◽  
Algal Mat

AbstractAn extensive system of mirabilite (Na2SO4 · 10H2O) beds has been mapped on the Ross Ice Shelf near Black Island. The salt beds are normally underlain by a thin layer of mud and their surface is covered by a non-marine algal mat and boulder lag. These authors suggest the salt has been formed by the displacement of sub-ice-shelf brines to the ice-shelf surface. Evidence also suggests that other terrestrial mirabilite beds in the McMurdo Sound area were formed in the same manner and deposited by the Ross Ice Shelf during its Wisconsin retreat from McMurdo Sound. Mirabilite salt in the dry valleys, southern Victoria Land, may have also originated from melt waters which dissolved ice-shelf mirabilite beds.

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