Simulation of blowing snow over the antarctic ice sheet

A preliminary simulation of blowing snow over the Antarctic continent made with a mesoscale atmospheric model is presented. Sensitivity experiments show that the increase of surface friction arising in conjunction with blowing snow has a relatively more important impact on the dynamics of strong katabatic winds than previously supposed. Sublimation in blowing snow over the Antarctic continent also contributes to the global sea-level budget. It is found that this contribution is of the same order of magnitude as the estimated present sea-level rise.

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On the thickness of the Antarctic ice, and its relations to that of the glacial epoch

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691021000050 ◽

2021 ◽

pp. 1-8

Author(s):

James CROLL ◽

David SUGDEN

Keyword(s):

Thermal Regime ◽

Freezing Point ◽

Ice Sheet ◽

Heat Sources ◽

Mean Velocity ◽

Point Estimates ◽

Glacial Epoch ◽

Antarctic Continent ◽

Global Sea Level ◽

The Antarctic

ABSTRACT At a time when nobody has yet landed on the Antarctic continent (1879), this presentation and accompanying paper predicts the morphology, dynamics and thermal regime of the Antarctic ice sheet. Mathematical modelling of the ice sheet is based on the assumptions that the thickness of tabular icebergs reflects the average thickness of the ice at the margin and that the surface gradients are comparable to those of reconstructed former ice sheets in the Northern Hemisphere. The modelling shows that (a) ice is thickest near the centre at the South Pole and thins towards the margin; (b) the thickness at the pole is independent of the amount of snowfall at that place; and (c) the mean velocity at the margin, assuming a mean annual snowfall of two inches per year, is 400–500 feet per year. The thermal regime of the ice sheet is influenced by three heat sources – namely, the bed, the internal friction of ice flow and the atmosphere. The latter is the most significant and, since ice has a downwards as well as horizontal motion, this carries cold ice down into the ice sheet. Since the temperature at which ice melts is lowered by pressure at a rate of 0.0137 °F for every atmosphere of pressure (something known since 1784), much of the ice sheet and its base must be below the freezing point. Estimates of the thickness of ice at the centre depend closely on the surface gradients assumed and range between 3 and 24 miles. Such uncertainty is of concern since both the volume and gravitational attraction of the ice mass have an effect on global sea level. In order to improve our estimate of the volume of ice, we will have to wait 76 years for John Glen to develop a realistic flow law for ice.

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Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing

The Cryosphere ◽

10.5194/tc-13-2615-2019 ◽

2019 ◽

Vol 13 (10) ◽

pp. 2615-2631 ◽

Cited By ~ 3

Author(s):

Michelle Tigchelaar ◽

Axel Timmermann ◽

Tobias Friedrich ◽

Malte Heinemann ◽

David Pollard

Keyword(s):

Sea Level ◽

Late Quaternary ◽

Ice Sheet ◽

Volume Changes ◽

Antarctic Ice Sheet ◽

Glacial Ice ◽

Ice Volume ◽

Global Sea Level ◽

The Individual ◽

The Antarctic

Abstract. Antarctic ice volume has varied substantially during the late Quaternary, with reconstructions suggesting a glacial ice sheet extending to the continental shelf break and interglacial sea level highstands of several meters. Throughout this period, changes in the Antarctic Ice Sheet were driven by changes in atmospheric and oceanic conditions and global sea level; yet, so far modeling studies have not addressed which of these environmental forcings dominate and how they interact in the dynamical ice sheet response. Here, we force an Antarctic Ice Sheet model with global sea level reconstructions and transient, spatially explicit boundary conditions from a 408 ka climate model simulation, not only in concert with each other but, for the first time, also separately. We find that together these forcings drive glacial–interglacial ice volume changes of 12–14 ms.l.e., in line with reconstructions and previous modeling studies. None of the individual drivers – atmospheric temperature and precipitation, ocean temperatures, or sea level – single-handedly explains the full ice sheet response. In fact, the sum of the individual ice volume changes amounts to less than half of the full ice volume response, indicating the existence of strong nonlinearities and forcing synergy. Both sea level and atmospheric forcing are necessary to create full glacial ice sheet growth, whereas the contribution of ocean melt changes is found to be more a function of ice sheet geometry than climatic change. Our results highlight the importance of accurately representing the relative timing of forcings of past ice sheet simulations and underscore the need for developing coupled climate–ice sheet modeling frameworks that properly capture key feedbacks.

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Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet

Science Advances ◽

10.1126/sciadv.1500589 ◽

2015 ◽

Vol 1 (8) ◽

pp. e1500589 ◽

Cited By ~ 59

Author(s):

Ricarda Winkelmann ◽

Anders Levermann ◽

Andy Ridgwell ◽

Ken Caldeira

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Carbon Emissions ◽

Fossil Fuel ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Global Sea Level ◽

The Antarctic

The Antarctic Ice Sheet stores water equivalent to 58 m in global sea-level rise. We show in simulations using the Parallel Ice Sheet Model that burning the currently attainable fossil fuel resources is sufficient to eliminate the ice sheet. With cumulative fossil fuel emissions of 10,000 gigatonnes of carbon (GtC), Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 m per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice Sheet becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West and East Antarctica results in a threshold increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice Sheet in its entirety with associated sea-level rise that far exceeds that of all other possible sources.

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PISM paleo simulations of the Antarctic Ice Sheet over the last two glacial cycles

10.5194/egusphere-egu2020-15081 ◽

2020 ◽

Author(s):

Torsten Albrecht ◽

Ricarda Winkelmann ◽

Anders Levermann

Keyword(s):

Boundary Conditions ◽

Sea Level ◽

Ice Sheet ◽

Sea Level Changes ◽

Glacial Cycles ◽

Antarctic Ice Sheet ◽

History Of ◽

Global Sea Level ◽

Glacial Time ◽

The Antarctic

<p>Simulations of the glacial-interglacial history of the Antarctic Ice Sheet provide insights into dynamic threshold behavior and estimates of the ice sheet's contributions to global sea-level changes, for the past, present and future. However, boundary conditions are weakly constrained, in particular at the interface of the ice-sheet and the bedrock. We use the Parallel Ice Sheet Model (PISM) to investigate the dynamic effects of different choices of input data and of various parameterizations on the sea-level relevant ice volume. We evaluate the model's transient sensitivity to corresponding parameter choices and to different boundary conditions over the last two glacial cycles and provide estimates of involved uncertainties. We also present isolated and combined effects of climate and sea-level forcing on glacial time scales.&#160;</p>

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Progress report on the Antarctic ice sheet

Polar Record ◽

10.1017/s0032247400050531 ◽

1960 ◽

Vol 10 (64) ◽

pp. 3-10 ◽

Cited By ~ 4

Author(s):

G. de Q. Robin

Keyword(s):

Sea Level ◽

Ross Sea ◽

Ice Sheet ◽

Great Depth ◽

Progress Report ◽

The Other ◽

The Past ◽

History Of ◽

Antarctic Continent ◽

The Antarctic

The art, science and sport of conducting scientific traverses across the Antarctic continent has advanced so rapidly during the past decade that we are making considerable progress towards understanding the main characteristics of that continent and its ice mantle. Many reports of recent work are provisional, so some changes of detail in the following account may eventually prove necessary. Nevertheless, some major features are now well established, such as the great depth of the subglacial floor to the east of the Ross Sea, and the observations that show considerable sections of the rock of East Antarctica† to be above sea level. On the other hand, the past glaciological history of the continent and the state of the present mass balance of the ice sheet still need much more investigation before we can be satisfied with the answers. The continued activity in Antarctica should result in our knowledge of the continent advancing much further during the coming decade.

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RESULTS FROM THE ANITA EXPERIMENT

Modern Physics Letters A ◽

10.1142/s0217732307024279 ◽

2007 ◽

Vol 22 (30) ◽

pp. 2237-2246 ◽

Cited By ~ 2

Author(s):

◽

ANDREA SILVESTRI ◽

S. W. BARWICK ◽

J. J. BEATTY ◽

D. Z. BESSON ◽

...

Keyword(s):

Neutrino Flux ◽

High Energy ◽

Long Duration ◽

Order Of Magnitude ◽

Successful Launch ◽

Balloon Experiment ◽

Antarctic Continent ◽

The Antarctic ◽

Prototype Instrument ◽

Better Than

The ANtarctic Impulse Transient Antenna (ANITA) is the first long-duration balloon experiment designed to search and measure the flux of Greisen–Zapsepin–Kuzmin (GZK) neutrinos. We present new limits on neutrinos fluxes of astronomical origin from data collected with the successful launch of a 2-antenna prototype instrument, called ANITA-lite, that circled the Antarctic continent for 18.4 days in January 2004. We performed a search for Ultra-High-Energy (UHE) neutrinos with energies above 3 × 1018 eV . No excess events above the background expectation were observed and a neutrino flux following E-2 spectrum for all neutrino flavors, is limited to [Formula: see text] for 1018.5 eV < Eν < 1023.5 eV at 90% confidence level. The launch of ANITA is scheduled for December 2006. Looking beyond ANITA, we describe a new idea, called ARIANNA (Antarctic Ross Iceshelf ANtenna Neutrino Array), to increase the sensitivity for GZK neutrinos by one order of magnitude better than ANITA.

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The role of history and strength of the oceanic forcing in sea-level projections from Antarctica with the Parallel Ice Sheet Model

10.5194/egusphere-egu2020-20029 ◽

2020 ◽

Author(s):

Ronja Reese ◽

Anders Levermann ◽

Torsten Albrecht ◽

Hélène Seroussi ◽

Ricarda Winkelmann

Keyword(s):

Mass Loss ◽

Sea Level ◽

Ice Sheet ◽

Ocean Warming ◽

Ice Streams ◽

Antarctic Ice Sheet ◽

Median Response ◽

Ice Shelves ◽

Order Of Magnitude ◽

The Antarctic

<p>Mass loss from the Antarctic Ice Sheet constitutes the largest uncertainty in projections of future sea-level rise. Ocean-driven melting underneath the floating ice shelves and subsequent acceleration of the inland ice streams is the major reason for currently observed mass loss from Antarctica and is expected to become more important in the future. Here we show that for projections of future mass loss from the Antarctic Ice Sheet, it is essential (1) to better constrain the sensitivity of sub-shelf melt rates to ocean warming, and (2) to include the historic trajectory of the ice sheet. In particular, we find that while the ice-sheet response in simulations using the Parallel Ice Sheet Model is comparable to the median response of models in three Antarctic Ice Sheet Intercomparison projects &#8211; initMIP, LARMIP-2 and ISMIP6 &#8211; conducted with a range of ice-sheet models, the projected 21st century sea-level contribution differs significantly depending on these two factors. For the highest emission scenario RCP8.5, this leads to projected ice loss ranging from 1.4 to 4.3 cm of sea-level equivalent in the ISMIP6 simulations where the sub-shelf melt sensitivity is comparably low, opposed to a likely range of 9.2 to 35.9 cm using the exact same initial setup, but emulated from the LARMIP-2 experiments with a higher melt sensitivity based on oceanographic studies. Furthermore, using two initial states, one with and one without a previous historic simulation from 1850 to 2014, we show that while differences between the ice-sheet configurations in 2015 are marginal, the historic simulation increases the susceptibility of the ice sheet to ocean warming, thereby increasing mass loss from 2015 to 2100 by about 50%. Our results emphasize that the uncertainty that arises from the forcing is of the same order of magnitude as the ice-dynamic response for future sea-level projections.</p>

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Semi-equilibrated global sea-level change projections for the next 10 000 years

Earth System Dynamics ◽

10.5194/esd-11-953-2020 ◽

2020 ◽

Vol 11 (4) ◽

pp. 953-976

Author(s):

Jonas Van Breedam ◽

Heiko Goelzer ◽

Philippe Huybrechts

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Sea Level Change ◽

Strong Increase ◽

Antarctic Ice Sheet ◽

Level Change ◽

Global Sea Level ◽

The Antarctic

Abstract. The emphasis for informing policy makers on future sea-level rise has been on projections by the end of the 21st century. However, due to the long lifetime of atmospheric CO2, the thermal inertia of the climate system and the slow equilibration of the ice sheets, global sea level will continue to rise on a multi-millennial timescale even when anthropogenic CO2 emissions cease completely during the coming decades to centuries. Here we present global sea-level change projections due to the melting of land ice combined with steric sea effects during the next 10 000 years calculated in a fully interactive way with the Earth system model of intermediate complexity LOVECLIMv1.3. The greenhouse forcing is based on the Extended Concentration Pathways defined until 2300 CE with no carbon dioxide emissions thereafter, equivalent to a cumulative CO2 release of between 460 and 5300 GtC. We performed one additional experiment for the highest-forcing scenario with the inclusion of a methane emission feedback where methane is slowly released due to a strong increase in surface and oceanic temperatures. After 10 000 years, the sea-level change rate drops below 0.05 m per century and a semi-equilibrated state is reached. The Greenland ice sheet is found to nearly disappear for all forcing scenarios. The Antarctic ice sheet contributes only about 1.6 m to sea level for the lowest forcing scenario with a limited retreat of the grounding line in West Antarctica. For the higher-forcing scenarios, the marine basins of the East Antarctic Ice Sheet also become ice free, resulting in a sea-level rise of up to 27 m. The global mean sea-level change after 10 000 years ranges from 9.2 to more than 37 m. For the highest-forcing scenario, the model uncertainty does not exclude the complete melting of the Antarctic ice sheet during the next 10 000 years.

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A numerical model of blowing snow around an Antarctic building

Annals of Glaciology ◽

10.1017/s0260305500016669 ◽

1994 ◽

Vol 20 ◽

pp. 341-346

Author(s):

I. Moore ◽

S.D. Mobbs ◽

D.B. Ingham ◽

J.C. King

Keyword(s):

Numerical Model ◽

Qualitative Agreement ◽

Progress Report ◽

Blowing Snow ◽

Ice Shelf ◽

British Antarctic Survey ◽

Drifting Snow ◽

Antarctic Continent ◽

Useful Life ◽

The Antarctic

The accumulation of drifting snow around buildings in regions of severe climate has important implications on their design and location. This paper studies one such building, at a station run by the British Antarctic Survey and located on the Brunt Ice Shelf at the edge of the Antarctic continent. Four previous stations have been built in the area, the buildings of which were designed to become covered in snow and all have been crushed within a few years. The current station, Halley V, consists of three buildings which are all raised from the ice shelf by means of legs. They were designed in such a way that the action of the wind blowing underneath the buildings would keep them-clear of snow. This paper describes a model which predicts the shape and position of drift formation, and then compares the results with those observed at Halley. This model is a first attempt to address the problem and as such the paper can be considered to be a progress report; improvements arc currently being made as part of continuing research. It is found that there is some qualitative agreement and possible reasons for a few quantitative discrepancies are discussed. Both the model and the true data show clearly that the new design is very effective in prolonging the useful life of the buildings.

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