Tracer transport in an isochronal ice-sheet model

Born, Andreas

doi:10.1017/jog.2016.111

Cited by 14 publications

(27 citation statements)

References 74 publications

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“…Just as ice-sheet-wide maps of radiostratigraphy could be used to constrain and initialise ice-flow models (e.g. Clarke and others, 2005; MacGregor and others, 2016 a ; Born, 2017; Goelzer and others, 2018), the surface layers mapped in this study could serve a similar purpose for models that can leverage this information. We are not aware of any large-scale model of the GrIS that is presently equipped to ingest these data directly, although Gilbert and others (2016) did find that a thermomechanical ice-flow model of the Barnes Ice Cap based on Elmer/Ice could successfully reproduce both the borehole-observed depth and the apparent rheological contrast of the Pleistocene–Holocene transition.…”

Section: Discussionmentioning

confidence: 99%

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

et al. 2020

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Each summer, surface melting of the margin of the Greenland Ice Sheet exposes a distinctive visible stratigraphy that is related to past variability in subaerial dust deposition across the accumulation zone and subsequent ice flow toward the margin. Here we map this surface stratigraphy along the northern margin of the ice sheet using mosaicked Sentinel-2 multispectral satellite imagery from the end of the 2019 melt season and finer-resolution WorldView-2/3 imagery for smaller regions of interest. We trace three distinct transitions in apparent dust concentration and the top of a darker basal layer. The three dust transitions have been identified previously as representing late-Pleistocene climatic transitions, allowing us to develop a coarse margin chronostratigraphy for northern Greenland. Substantial folding of late-Pleistocene stratigraphy is observed but uncommon. The oldest conformal surface-exposed ice in northern Greenland is likely located adjacent to Warming Land and may be up to ~55 thousand years old. Basal ice is commonly exposed hundreds of metres from the ice margin and may indicate a widespread frozen basal thermal state. We conclude that the ice margin across northern Greenland offers multiple opportunities to recover paleoclimatically distinct ice relative to previously studied regions in southwestern Greenland.

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Section: Discussionmentioning

confidence: 99%

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

et al. 2020

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“…Just as ice-sheet-wide maps of radiostratigraphy could be used to constrain and initialise ice-flow models (e.g. Clarke and others, 2005;MacGregor and others, 2016a;Born, 2017;Goelzer and others, 2018), the surface layers mapped in this study could serve a similar purpose for models that can leverage this information. We are not aware of any large-scale model of the GrIS that is presently equipped to ingest these data directly, although Gilbert and others (2016) did find that a thermomechanical ice-flow model of the Barnes Ice Cap based on Elmer/Ice could successfully reproduce both the borehole-observed depth and the apparent rheological contrast of the Pleistocene-Holocene transition.…”

Section: Journal Of Glaciology 679mentioning

confidence: 99%

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

MacGregor

Fahnestock

Colgan

et al. 2020

Preprint

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<p>Each summer, surface melting of the margin of the Greenland Ice Sheet exposes a distinctive visible stratigraphy that is related to past variability in subaerial dust deposition across the accumulation zone and subsequent ice flow toward the margin. Here we map this surface stratigraphy along the northern margin of the ice sheet using mosaicked Sentinel-2 multispectral satellite imagery from the end of the 2019 melt season and finer-resolution WorldView-2/3 imagery for smaller regions of interest. We trace three distinct transitions in apparent dust concentration and the top of a darker basal layer. The three dust transitions have been identified previously as representing late-Pleistocene climatic transitions, allowing us to develop a coarse margin chronostratigraphy for northern Greenland. Substantial folding of late-Pleistocene stratigraphy is observed but uncommon. The oldest conformal surface-exposed ice in northern Greenland is likely located adjacent to Warming Land and may be up to ~55 thousand years old. Basal ice is commonly exposed hundreds of meters from the ice margin and may indicate a widespread frozen basal thermal state. We conclude that the ice margin across northern Greenland offers multiple compelling opportunities to recover paleoclimatically valuable ice relative to previously studied regions in southwestern Greenland.</p>

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“…For the same reason, boxes with a depth index of 2 to 14 can only contain masses above m split = 300 kg m −2 , where liquid water refreezes. A conceptually similar vertical grid is used in the isochronal ice sheet model of Born (2017). Horizontal interactions between columns are not simulated.…”

Section: Model Domain and Discretizationmentioning

confidence: 99%

“…The long-term mass balance may be notably reduced when subject to interannual variability in the forcing because of its highly nonlinear response to deviations from the climatological average (Mikkelsen et al, 2018). This effect is exacerbated by the fact that even initially very small changes in the surface mass balance accelerate over time due to the ice-elevation feedback, leading to the complete loss of ice in certain regions (Born and Nisancioglu, 2012). In addition, the loss of ice causes profound changes in the local atmospheric circulation, which feed back into the energy and mass balance (Merz et al, 2014a, b).…”

Section: Introductionmentioning

confidence: 99%

An efficient surface energy–mass balance model for snow and ice

2019

Self Cite

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Abstract. A comprehensive understanding of the state and dynamics of the land cryosphere and associated sea level rise is not possible without taking into consideration the intrinsic timescales of the continental ice sheets. At the same time, the ice sheet mass balance is the result of seasonal variations in the meteorological conditions. Simulations of the coupled climate–ice-sheet system thus face the dilemma of skillfully resolving short-lived phenomena, while also being computationally fast enough to run over tens of thousands of years. As a possible solution, we present the BErgen Snow SImulator (BESSI), a surface energy and mass balance model that achieves computational efficiency while simulating all surface and internal fluxes of heat and mass explicitly, based on physical first principles. In its current configuration it covers most land areas of the Northern Hemisphere. Input data are daily values of surface air temperature, total precipitation, and shortwave radiation. The model is calibrated using present-day observations of Greenland firn temperature, cumulative Greenland mass changes, and monthly snow extent over the entire domain. The results of the calibrated simulations are then discussed. Finally, as a first application of the model and to illustrate its numerical efficiency, we present the results of a large ensemble of simulations to assess the model's sensitivity to variations in temperature and precipitation.

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Tracer transport in an isochronal ice-sheet model

Cited by 14 publications

References 74 publications

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

The age of surface-exposed ice along the northern margin of the Greenland Ice Sheet

An efficient surface energy–mass balance model for snow and ice

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