Review of “Modelling Ross Ice Shelf melting effect on the Southern Ocean in quasi-equilibrium” by Liu

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.

Download Full-text

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

10.5194/tc-2017-228 ◽

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.

Download Full-text

Identifying Ocean Swell Generation Events from Ross Ice Shelf Seismic Data

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-19-0093.1 ◽

2019 ◽

Vol 36 (11) ◽

pp. 2171-2189 ◽

Cited By ~ 2

Author(s):

Momme C. Hell ◽

Bruce D. Cornelle ◽

Sarah T. Gille ◽

Arthur J. Miller ◽

Peter D. Bromirski

Keyword(s):

Southern Ocean ◽

Low Frequency ◽

Radial Distance ◽

Optimization Procedure ◽

Wave Model ◽

Heat Fluxes ◽

Supervised Machine Learning ◽

Extratropical Cyclones ◽

Ice Shelf ◽

Ross Ice Shelf

AbstractStrong surface winds under extratropical cyclones exert intense surface stresses on the ocean that lead to upper-ocean mixing, intensified heat fluxes, and the generation of waves, that, over time, lead to swell waves (longer than 10-s period) that travel long distances. Because low-frequency swell propagates faster than high-frequency swell, the frequency dependence of swell arrival times at a measurement site can be used to infer the distance and time that the wave has traveled from its generation site. This study presents a methodology that employs spectrograms of ocean swell from point observations on the Ross Ice Shelf (RIS) to verify the position of high wind speed areas over the Southern Ocean, and therefore of extratropical cyclones. The focus here is on the implementation and robustness of the methodology in order to lay the groundwork for future broad application to verify Southern Ocean storm positions from atmospheric reanalysis data. The method developed here combines linear swell dispersion with a parametric wave model to construct a time- and frequency-dependent model of the dispersed swell arrivals in spectrograms of seismic observations on the RIS. A two-step optimization procedure (deep learning) of gradient descent and Monte Carlo sampling allows detailed estimates of the parameter distributions, with robust estimates of swell origins. Median uncertainties of swell source locations are 110 km in radial distance and 2 h in time. The uncertainties are derived from RIS observations and the model, rather than an assumed distribution. This method is an example of supervised machine learning informed by physical first principles in order to facilitate parameter interpretation in the physical domain.

Download Full-text

Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004

10.3133/i2600h ◽

2007 ◽

Keyword(s):

Shelf Area ◽

Coastal Change ◽

Ice Shelf ◽

Ross Ice Shelf

Download Full-text

NEW TECTONIC BOUNDARY AND GONDWANA MARGIN INHERITANCE REVEALED IN CRUST BENEATH ROSS ICE SHELF, ANTARCTICA, THROUGH ROSETTA-ICE PROJECT INTEGRATION OF AEROGEOPHYSICS, GEOLOGY, AND OCEAN DATA

10.1130/abs/2017am-304189 ◽

2017 ◽

Author(s):

Christine S. Siddoway ◽

◽

Kirsteen Tinto ◽

Robin E. Bell ◽

Alec Lockett

Keyword(s):

Ice Shelf ◽

Ross Ice Shelf ◽

Project Integration ◽

Gondwana Margin ◽

Tectonic Boundary

Download Full-text

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

Geosciences ◽

10.3390/geosciences11040155 ◽

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.

Download Full-text

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

Antarctic Science ◽

10.1017/s0954102020000498 ◽

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.

Download Full-text