Atmospheric Dynamics Footprint on the January 2016 Ice Sheet Melting in West Antarctica

2020 ◽  
Author(s):  
Xiaoming Hu ◽  
Sergio Sejas ◽  
Ming Cai ◽  
Zhenning Li ◽  
Song Yang
Keyword(s):  
Energy Flux ◽  
Ross Sea ◽  
Ice Sheet ◽  
Radiative Energy ◽  
West Antarctica ◽  
West Antarctic Ice Sheet ◽  
Surface Energy Flux ◽  
West Antarctic ◽  
Melting Period ◽  
Vapor Cloud

<p>In January of 2016, the Ross Sea sector of the West Antarctic Ice Sheet experienced a three-week long melting episode. Here we quantify the association of the large-extent and long-lasting melting event with the enhancement of the downward longwave (LW) radiative fluxes at the surface due to water vapor, cloud, and atmospheric dynamic feedbacks using the ERA-Interim dataset. The abnormally long-lasting temporal surges of atmospheric moisture, warm air, and low clouds increase the downward LW radiative energy flux at the surface during the massive ice-melting period. The concurrent timing and spatial overlap between poleward wind anomalies and positive downward LW radiative surface energy flux anomalies due to warmer air temperature provides direct evidence that warm air advection from lower latitudes to West Antarctica causes the rapid long-lasting warming and vast ice mass loss in January of 2016.</p>

scholarly journals Ancient pre-glacial erosion surfaces preserved beneath the West Antarctic Ice Sheet

2014 ◽  
Vol 2 (2) ◽  
pp. 681-713
Author(s):  
K. C. Rose ◽  
N. Ross ◽  
R. G. Bingham ◽  
H. F. J. Corr ◽  
F. Ferraccioli ◽  
...  
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Deep Ocean ◽  
Ocean Basin ◽  
Weddell Sea ◽  
West Antarctica ◽  
Ice Streams ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Wave Erosion

Abstract. We present ice-penetrating radar evidence for ~150 km wide planation surfaces beneath the upstream Institute and Möller Ice Streams, West Antarctica. Accounting for isostatic rebound under ice-free conditions, the surfaces would be around sea level. We, thus, interpreted the surfaces as ancient, marine erosion (wave-cut) platforms. The scale and geometry of the platforms are comparable to erosion surfaces identified in the Ross Sea embayment, on the opposite side of West Antarctica. Their formation is likely to have begun after the development of the deep ocean basin of the Weddell Sea (~160 Myr ago). In order to form wave-cut platforms, the sea must be relatively free of sea ice for a sustained period to allow wave erosion at wave base. As a consequence, the most recent period of sustained marine erosion is likely to be the Mid-Miocene Climatic Optimum (17–15 Ma), when warm atmospheric and oceanic temperatures would have prevented ice from blanketing the coast during periods of ice-sheet retreat. The erosion surfaces are preserved in this location due to the collective action of the Pirrit and Martin–Nash Hills on ice-sheet flow, which results in a region of slow flowing, cold-based ice downstream of this major topographic barrier. This investigation shows that smooth, flat subglacial topography does not always correspond with regions of either present or former fast ice flow, as has previously been assumed.

scholarly journals The paradox of a long grounding during West Antarctic Ice Sheet retreat in Ross Sea

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Philip J. Bart ◽  
Benjamin J. Krogmeier ◽  
Manon P. Bart ◽  
Slawek Tulaczyk
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

Reassessing the Contribution of West Antarctica to Last Interglacial Sea Level in Light of 3D Mantle Viscosity Structure

2021 ◽  
Author(s):  
Linda Pan ◽  
Evelyn M. Powell ◽  
Konstantin Latychev ◽  
Jerry X. Mitrovica ◽  
Jessica R. Creveling ◽  
...  
Keyword(s):  
Sea Level ◽  
Complex Structure ◽  
Ice Sheet ◽  
West Antarctica ◽  
Last Interglacial ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Low Viscosity ◽  
Global Mean Sea Level ◽  
Warming World

<p>Studies of peak global mean sea level (GMSL) during the Last Interglacial (LIG; 130-116 ka) commonly cite values ranging from ~2-5 m for the maximum contribution from grounded, marine-based sectors of the West Antarctic Ice Sheet (WAIS). However, this estimate neglects viscoelastic crustal uplift and the associated meltwater flux out of marine sectors as they are exposed, a contribution considered to be small and slowly-accumulating. This assumption should be revisited, as a range of evidence indicates that West Antarctica is underlain by shallow mantle of anomalously low viscosity. By incorporating this complex structure into a gravitationally self-consistent sea-level calculation, we find that GMSL differs substantially from previous estimates. Our results indicate that these estimates thus require a reassessment of the contribution to GMSL rise from WAIS collapse, as will ice sheet models that do not account for the uplift mechanism. This conclusion has important implications for the sea level budget not only during the LIG, but also for all previous interglacials and projections of GMSL change in the future warming world.  </p>

Active subglacial volcanism in West Antarctica as assessed by airborne geophysics: Distribution and context

2020 ◽  
Author(s):  
Donald Blankenship ◽  
Enrica Quatini ◽  
Duncan Young
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Rift System ◽  
West Antarctica ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Volcanism

<p>A combination of aerogeophysics, seismic observations and direct observation from ice cores and subglacial sampling has revealed at least 21 sites under the West Antarctic Ice sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogenous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially underrepresented. Unsurprisingly, the sites of active subglacial volcanism we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea to Siple Coast lithospheric transition.</p>

scholarly journals A Three-Dimensional Time-Dependent Model of the West Antarctic Ice Sheet

1984 ◽  
Vol 5 ◽  
pp. 29-36 ◽  
Author(s):  
W. F. Budd ◽  
D. Jenssen ◽  
I. N. Smith
Keyword(s):  
Environmental Changes ◽  
Three Dimensional ◽  
Ice Sheet ◽  
West Antarctica ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Image Position ◽  
Basal Shear

The area of West Antarctica which drains into the Ross Ice Shelf is examined for the purpose of understanding its dynamics and developing a numerical model to study its reaction to environmental changes. A high resolution 20 km grid is used to compile a database for surface and bedrock elevation, accumulation, and surface temperatures. Balance velocities Vb are computed and found to approximate observed velocities. These balance velocities are used with basal shear stress and ice thickness above buoyancy Z* to derive parameters k2, p and q for a sliddinq relation of the form Reasonable matching is obtained for p = 1, q = 2 and k2= 5 × 106 m3 bar−1 a−1. This sliding relation is then used in a first complete dynamic and thermodynamic velocity calculation for West Antarctica and for an improved simulation of the whole Antarctic ice sheet.

scholarly journals A time marker at 17.5 kyr BP detected throughout West Antarctica

2005 ◽  
Vol 41 ◽  
pp. 47-51 ◽  
Author(s):  
Robert W. Jacobel ◽  
Brian C. Welch
Keyword(s):  
Accumulation Rate ◽  
Ice Sheet ◽  
Weddell Sea ◽  
West Antarctica ◽  
Layer Depth ◽  
Time Marker ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Stream ◽  
Siple Dome

AbstractDeep radar soundings as part of the International Trans-Antarctic Scientific Expedition (US-ITASE) traverses in West Antarctica have revealed a bright internal reflector that we have imaged throughout widespread locations across the ice sheet. The layer is seen in traverses emanating from Byrd Station in four directions and has been traced continuously for distances of 535km toward the Weddell Sea drainage, 500km toward South Pole, 150km toward the Executive Committee Range and 160km toward Kamb Ice Stream (former Ice Stream C). The approximate area encompassed by the layer identified in these studies is 250 000km2. If the layer identification can also be extended to Siple Dome where we have additional radar soundings (Jacobel and others, 2000), the approximate area covered would increase by 50%. In many locations echo strength from the layer rivals the bed echo in amplitude even though it generally lies at a depth greater than half the ice thickness. At Byrd Station, where the layer depth is 1260 m, an age of ~17.5 kyr BP has been assigned based on the Blunier and Brook (2001) chronology. Hammer and others (1997) note that the acidity at this depth is >20 times the amplitude of any other part of the core. The depiction of this strong and widespread dated isochrone provides a unique time marker for much of the ice in West Antarctica. We apply a layer-tracing technique to infer the depth–time scale at the inland West Antarctic ice sheet divide and use this in a simple model to estimate the average accumulation rate.

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