Verification of model simulated mass balance, flow fields and tabular calving events of the Antarctic ice sheet against remotely sensed observations

Ren, Diandong; Leslie, Lance M.; Lynch, M. J.

doi:10.1007/s00382-012-1464-3

Cited by 12 publications

(19 citation statements)

References 82 publications

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“…This likely reflects warm seawater during the Antarctic summer, and an increase in the relative velocity of the iceberg resulting from drift in winter (Figure 3b) promoted the basal melting [17,45]. The longitudinal stretching of the iceberg after August 2018 could also contribute to the decrease in the freeboard as it is accompanied by ice thinning [44]. Assuming that CryoSat-2 observations reflect the maximum radar returns from the snow surface on the iceberg, the averaging rate of thickness change during February-November 2018 was calculated as −12.89 ± 3.34 m/year from Equation (1) based on an averaging snow depth change of 0.82 ± 0.06 m/year.…”

Section: Resultsmentioning

confidence: 99%

“…Longitudinal stretching of ice mass is possible if external restraining forces on its boundaries are small or not present [42,43]. Ice shelves experience similar longitudinal stretching and thinning when they lose buttressing forces due to unpinning or iceberg calving [44]. The observation of A68A shows that the sea ice in the northwestern region of A68A started to disappear since July 2018 ( Figure 4).…”

Section: Resultsmentioning

confidence: 99%

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Changes in a Giant Iceberg Created from the Collapse of the Larsen C Ice Shelf, Antarctic Peninsula, Derived from Sentinel-1 and CryoSat-2 Data

et al. 2019

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The giant tabular iceberg A68 broke away from the Larsen C Ice Shelf, Antarctic Peninsula, in July 2017. The evolution of A68 would have been affected by both the Larsen C Ice Shelf, the surrounding sea ice, and the nearby shallow seafloor. In this study, we analyze the initial evolution of iceberg A68A—the largest originating from A68—in terms of changes in its area, drift speed, rotation, and freeboard using Sentinel-1 synthetic aperture radar (SAR) images and CryoSat-2 SAR/Interferometric Radar Altimeter observations. The area of iceberg A68A sharply decreased in mid-August 2017 and mid-May 2018 via large calving events. In September 2018, its surface area increased, possibly due to its longitudinal stretching by melting of surrounding sea ice. The decrease in the area of A68A was only 2% over 1.5 years. A68A was relatively stationary until mid-July 2018, while it was surrounded by the Larsen C Ice Shelf front and a high concentration of sea ice, and when its movement was interrupted by the shallow seabed. The iceberg passed through a bay-shaped region in front of the Larsen C Ice Shelf after July 2018, showing a nearly circular motion with higher speed and greater rotation. Drift was mainly inherited from its rotation, because it was still located near the Bawden Ice Rise and could not pass through by the shallow seabed. The freeboard of iceberg A68A decreased at an average rate of −0.80 ± 0.29 m/year during February–November 2018, which could have been due to basal melting by warm seawater in the Antarctic summer and increasing relative velocity of iceberg and ocean currents in the winter of that year. The freeboard of the iceberg measured using CryoSat-2 could represent the returned signal from the snow surface on the iceberg. Based on this, the average rate of thickness change was estimated at −12.89 ± 3.34 m/year during the study period considering an average rate of snow accumulation of 0.82 ± 0.06 m/year predicted by reanalysis data from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). The results of this study reveal the initial evolution mechanism of iceberg A68A, which cannot yet drift freely due to the surrounding terrain and sea ice.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Changes in a Giant Iceberg Created from the Collapse of the Larsen C Ice Shelf, Antarctic Peninsula, Derived from Sentinel-1 and CryoSat-2 Data

et al. 2019

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“…In total, there are 15 years of GRACE measurements of time variations in gravity changes over the globe, before the quality of the data degrades. Before 2002, or for areas with land surface areas that are too small to be resolved by GRACE data, a land surface scheme within a model referred to as Scalable Extensible Geofluid Modeling framework for ENvironmenTal issues (SEGMENT [14,20,21], will be detailed in Subsection 2.2), driven by atmospheric parameters, is used to simulate groundwater fluctuations. The earthquake triad is interlinked with groundwater fluctuations.…”

Section: Numerical Model Setup and Parameterization Of The Earthquakementioning

confidence: 99%

“…The present amount of GM ( Figure S2c) is deduced from surface velocity using the method in Ref. [21]. Future variations of GM are diagnosed (relevant equation is detailed in the next subsection on GM generation that immediately follows).…”

Section: Numerical Earthquake Modelmentioning

confidence: 99%

How Droughts Influence Earthquakes

Ren¹,

Fu²

2019

Adv Environ Stud

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This study formulates co-seismic conditions involving three specific angles that relate to balancing of the magnitude and direction of the associated forces that collectively when perturbed can precipitate an earthquake event. The hypothesis developed in this research (1) Enlarges our knowledge base by extending the canonical frictional phenomena into fatigue conditions at the plate interface; 2) Indicates that large scale, extended droughts, by exerting cyclical unloading, create two mechanisms for enhancing tectonic instability and the associated triggering earthquakes; and (3) Integrates the role of (generic) groundwater fluctuations at the nexus thereby linking climate change caused extremes and perturbations of the tectonic earthquake cycle. With this hypothesis, mechanics-based process modelling has the potential to be used to determine the locations and development of the evolving regional stresses and to answer the questions of why, when and how extreme will be a specific earthquake event.

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“…Here, the focus is on model projections of sea level rise (SLR) from ice sheet melting in a warming climate. The modelling system is SEG-MENT [1,2], which embraces a range of geophysical flows, has a modular design and supports multi-rheology flows. For ice-sheet modelling, the SEGMENT-Ice module incorporates the complexities of both internal flow, and interactions of the ice sheet with its external environment at its upper and lower boundaries, and along its perimeter.…”

Section: Introductionmentioning

confidence: 99%