Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica

Still, Holly; Hulbe, Christina L.

doi:10.5194/tc-15-2647-2021

Cited by 8 publications

(5 citation statements)

References 75 publications

(95 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the east side of RIS, the Shirase Coast Ice Rumples (SCIR) at the outlet of the MacAyeal and Bindschadler Ice Streams significantly modify the flow field and ice thickness due to grounding of the ice, consistent with the simulated pinning points in Section . Thinning of ice downstream of SCIR and diversion of the shear margins towards Roosevelt Island (RI) are both dynamical e ects that modify the buttressing capability of ice in this region (Still and others, 2019;Still and Hulbe, 2021). In our inferred B field, the ice covering the rumples is inferred to be softer while the downstream ice connected to RI is inferred to be sti er.…”

Section: West Antarctica Ice Shelvesmentioning

confidence: 80%

Variational inference of ice shelf rheology with physics-informed machine learning

Riel¹,

Minchew²

2022

Preprint

View full text Add to dashboard Cite

Floating ice shelves that fringe the coast of Antarctica resist the flow of grounded ice into the ocean. One of the key factors governing the amount of flow-resistance provided by an ice shelf is the rigidity of the ice that constitutes it. Ice rigidity is highly heterogeneous and must be calibrated from spatially-continuous surface observations assimilated into an ice flow model. Moreover, realistic uncertainties in calibrated rigidity values are needed to quantify uncertainties in forecasts of future shelf flow. Here, we present a physics-informed machine learning framework for inferring the full probability distribution of rigidity values for a given ice shelf, conditioned on surface velocity and thickness fields derived from remote sensing data. We employ variational inference to jointly train neural networks and a variational Gaussian Process to reconstruct surface observations and rigidity values and uncertainties. Application of the framework to synthetic and large ice shelves in Antarctica demonstrate that rigidity is well-constrained in areas where deformation of ice is measurable within the noise level of the observations. Further reduction in uncertainties can be achieved by complementing variational inference with conventional inversion methods. Our results demonstrate a path forward for continuous calibration of ice flow parameters from remote sensing observations.

show abstract

Section: West Antarctica Ice Shelvesmentioning

confidence: 80%

Variational inference of ice shelf rheology with physics-informed machine learning

Riel¹,

Minchew²

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Thus, significant (the most prominent zones of sediment accumulation along the Baltic depression) accumulation of unconsolidated sediments along geological steps indicates the importance of pinning points in ice stabilisation (e.g. Favier et al, 2016;Still and Hulbe, 2021). The only prominent high on the Baltic bed where we do not map accumulations of glaciogenic sediments is Åland Sill, possibly because of patchier sediment availability over the crystalline bedrock.…”

Section: What Was the Role Of Bedrock Structures Inmentioning

confidence: 85%

Reconstructing dynamics of the Baltic Ice Stream Complex during deglaciation of the Last Scandinavian Ice Sheet

Szuman,

Kalita,

Diemont

et al. 2024

The Cryosphere

View full text Add to dashboard Cite

Abstract. Landforms left behind by the last Scandinavian Ice Sheet (SIS) offer an opportunity to investigate controls governing ice sheet dynamics. Terrestrial sectors of the ice sheet have received considerable attention from landform and stratigraphic investigations. In contrast, despite its geographical importance, the Baltic Sea remains poorly constrained due to limitations in bathymetric data. Both ice-sheet-scale investigations and regional studies at the southern periphery of the SIS have considered the Baltic depression to be a preferential route for ice flux towards the southern ice margin throughout the last glaciation. During the deglaciation the Baltic depression hosted the extensive Baltic Ice Lake, which likely exerted a considerable control on ice dynamics. Here we investigate the Baltic depression using newly available bathymetric data and peripheral topographic data. These data reveal an extensive landform suite stretching from Denmark in the west to Estonia in the east and from the southern European coast to the Åland Sea, comprising an area of 0.3 million km2. We use these landforms to reconstruct aspects of the ice dynamic history of the Baltic sector of the ice sheet. Landform evidence indicates a complex retreat pattern that changes from lobate ice margins with splaying lineations to parallel mega-scale glacial lineations (MSGLs) in the deeper depressions of the Baltic Basin. Ice margin still-stands on underlying geological structures indicate the likely importance of pinning points during deglaciation, resulting in a stepped retreat signal. Over the span of the study area we identify broad changes in the ice flow direction, ranging from SE–NW to N–S and then to NW–SE. MSGLs reveal distinct corridors of fast ice flow (ice streams) with widths of 30 km and up to 95 km in places, rather than the often-interpreted Baltic-wide (300 km) accelerated ice flow zone. These smaller ice streams are interpreted as having operated close behind the ice margin during late stages of deglaciation. Where previous ice-sheet-scale investigations inferred a single ice source, our mapping identifies flow and ice margin geometries from both Swedish and northern Bothnian sources. We anticipate that our landform mapping and interpretations may be used as a framework for more detailed empirical studies by identifying targets to acquire high-resolution bathymetry and sediment cores and also for comparison with numerical ice sheet modelling.

show abstract

“…4), outwash fans (Noormets and Flodén, 2002b), and large moraines in the central Baltic is consistently associated with these geological structures. This indicates the importance of pinning points in ice stabilisation (e.g., Favier et al, 2016;Still and Hulbe, 2021). The only prominent high on the Baltic bed where we do not map accumulations of glacigenic sediments is Åland Sill, possibly because of patchier sediment availability over the crystalline bedrock.…”

Section: What Was the Role Of Bedrock Structures In Controlling Stepp...mentioning

confidence: 88%

Evaluation of the role of the Baltic depression during deglaciation of the last Scandinavian Ice Sheet; a landform-driven investigation

Szuman

Kalita

Diemont

et al. 2023

Preprint

View full text Add to dashboard Cite

Abstract. Landforms left behind by the last Scandinavian Ice Sheet (SIS) offer an opportunity to investigate controls governing ice sheet dynamics. Terrestrial sectors of the ice sheet have received considerable attention by landform and stratigraphic investigations, but much less so for marine areas such as in the Baltic Sea. In contrast, despite its geographical importance, the Baltic Sea remain poorly constrained due to limitations in bathymetric data. The Baltic depression hosted the extensive Baltic Ice Lake, which likely exerted a considerable control on ice dynamics, providing an aqueous calving front that might have resulted in rapid collapse of this ice sheet sector. Both ice sheet scale investigations and regional studies at the southern periphery of the SIS have considered the Baltic depression as a preferential conduit for ice flux towards the southern ice margin throughout the last glaciation. Here we test this hypothesis using newly available bathymetric data and peripheral topographic data. For the first time, these data reveal an extensive landform suite stretching from Denmark in the west to Estonia in the east and from the southern European coast to the Aland Sea, comprising an area of 0.3 million km2. We use these landforms to reconstruct the ice dynamic history of the Baltic sector of the SIS. Landform evidence indicates a complex retreat pattern that changes from lobate ice margins with splaying lineations to parallel MSGL in the deeper depressions of the Baltic Basin. Ice margin still-stands on underlying geological structures indicate the likely importance of pinning points during deglaciation resulting in a stepped retreat signal. Over the length of the study area we identify broad changes in ice flow geometry, ranging from SE-NW to N-S and then to NW-SE. Mega-scale glacial lineations reveal distinct corridors of fast ice flow (ice streams) with widths of 30 up to 95 km, rather that the often-interpreted Baltic-wide (300 km) accelerated ice flow zone. These smaller ice streams are interpreted to have operated during late stages of deglaciation. Where previous ice sheet-scale investigations inferred a single ice source, our mapping identifies flow and ice marginal geometries from both Swedish and north Bothnian sources. We anticipate our landform mapping and interpretations may be used as a framework for more detailed empirical studies by identifying targets to acquire high resolution bathymetry and sediment cores and also for comparison with numerical ice sheet modelling.

show abstract

Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica

Cited by 8 publications

References 75 publications

Variational inference of ice shelf rheology with physics-informed machine learning

Variational inference of ice shelf rheology with physics-informed machine learning

Reconstructing dynamics of the Baltic Ice Stream Complex during deglaciation of the Last Scandinavian Ice Sheet

Evaluation of the role of the Baltic depression during deglaciation of the last Scandinavian Ice Sheet; a landform-driven investigation

Contact Info

Product

Resources

About