A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle

Morzadec, K. Le; Tarasov, Lev; Morlighem, Mathieu; Seroussi, Hélène

doi:10.5194/gmd-8-3199-2015

Cited by 15 publications

(23 citation statements)

References 37 publications

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“…The ice margin retreated on the order of 150 km inland from the present-day coastline in response to warming during the early and middle Holocene (Briner et al, 2016). This landscape is punctuated by widely traceable moraine sequences (Weidick, 1968;Ten Brink and Weidick, 1974) that extend nearly 600 km throughout western Greenland and provide a constraint on the past retreat pattern of the GrIS in this region; the chronology of these moraines continues to be refined (Weidick et al, 2004(Weidick et al, , 2012Young et al, 2013;Larsen et al, 2015;Lesnek and Briner, 2018). This history provides a benchmark for ice sheet model-data comparisons that will further enhance our understanding of the processes that influenced GrIS variability during the past while at the same time helping to highlight deficiencies in existing model frameworks.…”

Section: Introductionmentioning

confidence: 99%

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The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)

et al. 2019

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Abstract. Geologic archives constraining the variability of the Greenland ice sheet (GrIS) during the Holocene provide targets for ice sheet models to test sensitivities to variations in past climate and model formulation. Even as data–model comparisons are becoming more common, many models simulating the behavior of the GrIS during the past rely on meshes with coarse horizontal resolutions (≥10 km). In this study, we explore the impact of model resolution on the simulated nature of retreat across southwestern Greenland during the Holocene. Four simulations are performed using the Ice Sheet System Model (ISSM): three that use a uniform mesh and horizontal mesh resolutions of 20, 10, and 5 km, and one that uses a nonuniform mesh with a resolution ranging from 2 to 15 km. We find that the simulated retreat can vary significantly between models with different horizontal resolutions based on how well the bed topography is resolved. In areas of low topographic relief, the horizontal resolution plays a negligible role in simulated differences in retreat, with each model instead responding similarly to retreat driven by surface mass balance (SMB). Conversely, in areas where the bed topography is complex and high in relief, such as fjords, the lower-resolution models (10 and 20 km) simulate unrealistic retreat that occurs as ice surface lowering intersects bumps in the bed topography that would otherwise be resolved as troughs using the higher-resolution grids. Our results highlight the important role that high-resolution grids play in simulating retreat in areas of complex bed topography, but also suggest that models using nonuniform grids can save computational resources through coarsening the mesh in areas of noncomplex bed topography where the SMB predominantly drives retreat. Additionally, these results emphasize that care must be taken with ice sheet models when tuning model parameters to match reconstructed margins, particularly for lower-resolution models in regions where complex bed topography is poorly resolved.

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Section: Introductionmentioning

confidence: 99%

“…(a) Mapped moraines and the existing chronology of ice retreat over the northern and southern portion of our domain. The mapped moraines and corresponding ages of retreat were taken fromLesnek and Briner (2018). (b, c) Simulated ice sheet margin for the different model resolutions shown over locations in the northern (b) and southern (c) domain.…”

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confidence: 99%

The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)

et al. 2019

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“…Tarasov et al, 2012) run at grid resolution of 0.5 • longitude by 0.25 • latitude. The model has been upgraded to hybrid shallow-ice and shallow-shelf physics, with ice dynamical core from Pollard and DeConto (2012) and includes: a 4 km deep permafrost resolving bed thermal component (Tarasov and Peltier, 2007), visco-elastic bedrock response with global ice-sheet and sea-level loading, sub-shelf melt, parametrizations for subgrid mass-balance and ice flow (Morzadec et al, 2015), and updated parametrizations for surface mass-balance and ice calving.…”

Section: Greenland Ice-sheetmentioning

confidence: 99%

The penultimate deglaciation: protocol for PMIP4 transient numerical simulations between 140 and 127 ka, version 1.0

Menviel¹,

Capron²,

Govin³

et al. 2019

Preprint

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Abstract. The penultimate deglaciation (PDG, ~ 138–128 thousand years before present, hereafter ka) is the transition from the penultimate glacial maximum to the Last Interglacial (LIG, ~ 129–116 ka). The LIG stands out as one of the warmest interglacials of the last 800 ka, with high-latitude temperature warmer than today and global sea level likely higher by at least 6 meters. Considering the transient nature of the Earth system, the LIG climate and ice-sheets evolution were certainly influenced by the changes occurring during the penultimate deglaciation. It is thus important to investigate, with coupled Atmosphere-Ocean General Circulation Models (AOGCMs), the climate and environmental response to the large changes in boundary conditions (i.e. orbital configuration, atmospheric greenhouse gas concentrations, ice-sheet geometry, and associated meltwater fluxes) occurring during the penultimate deglaciation. A deglaciation working group has recently been set up as part of the Paleoclimate Modelling Intercomparison Project (PMIP) phase 4, with a protocol to perform transient simulations of the last deglaciation (19–11 ka; although the protocol covers 26–0 ka). Similar to the last deglaciation, the disintegration of continental ice-sheets during the penultimate deglaciation led to significant changes in the oceanic circulation during Heinrich Stadial 11 (~ 136–129 ka). However, the two deglaciations bear significant differences in magnitude and temporal evolution of climate and environmental changes. Here, as part of the PAGES-PMIP working group on Quaternary Interglacials, we propose a protocol to perform transient simulations of the penultimate deglaciation under the auspices of PMIP4. This design includes time-varying changes in orbital forcing, greenhouse gas concentrations, continental ice-sheets as well as freshwater input from the disintegration of continental ice-sheets. This experiment is designed for AOGCMs to assess the coupled response of the climate system to all forcings. Additional sensitivity experiments are proposed to evaluate the response to each forcing. Finally, a selection of paleo records representing different parts of the climate system is presented, providing an appropriate benchmark for upcoming model-data comparisons across the penultimate deglaciation.

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“…The temperature forcing is adjusted throughout the run using a lapse rate correction of 5°C km -1 (Abe-Ouchi et al, 2007) to account for changes in ice surface height throughout the simulation, while elevation-dependent desertification is included (Budd and Smith, 1981) to ensure reduction in precipitation by a factor of 2 for 30 every kilometer change in ice sheet surface elevation. Further details regarding the positive degree day scheme implemented within ISSM can be found in Le Morzadec et al (2015).…”

Section: Smb (Smb)mentioning

confidence: 99%

The impact of model resolution on the simulated Holocene retreat of the Southwestern Greenland Ice Sheet using the Ice Sheet System Model (ISSM)

Cuzzone¹,

Schlegel²,

Morlighem³

et al. 2018

Preprint

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Abstract. Geologic archives constraining the variability of the Greenland Ice Sheet (GrIS) during the Holocene provide targets for ice sheet models to test sensitivities to variations in past climate and model formulation. Even as data-model comparisons are becoming more common, many models simulating the behaviour of the GrIS during the past rely on meshes with coarse horizontal resolution (≥ 10 km). In this study, we explore the impact of model resolution on the simulated nature of retreat across Southwestern Greenland during the Holocene. Four simulations are performed using the Ice Sheet System Model (ISSM); three which use a uniform mesh and horizontal mesh resolutions of 20 km, 10 km, and 5 km and one non-uniform mesh with resolution ranging from 2 km to 15 km. We find that the simulated retreat can vary significantly between models with different horizontal resolutions based on how well the bed topography is resolved. In areas of low topographic relief, model resolution plays a negligible role in simulated differences in retreat, with models instead responding similarly to surface mass balance (SMB) driven retreat. Conversely, in areas where the bed topography is complex and high in relief, such as fjords, lower resolution models (10 km and 20 km) simulate unrealistic retreat driven as ice-surface lowering intersects bumps in the bed topography which would otherwise be resolved as troughs in the higher resolution models. Our results highlight the important role that high resolution grids play in simulating retreat in areas of complex bed topography, but also suggest that models using non-uniform grids can save computational resources through coarsening the mesh in areas of non-complex bed topography where the SMB drives retreat. Additionally, these results emphasize that care must be taken with ice sheet models when tuning model parameters to match reconstructed margins, particularly for lower resolution models in regions where complex bed topography is poorly resolved.

show abstract

A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle

Cited by 15 publications

References 37 publications

The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)

The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)

The penultimate deglaciation: protocol for PMIP4 transient numerical simulations between 140 and 127 ka, version 1.0

The impact of model resolution on the simulated Holocene retreat of the Southwestern Greenland Ice Sheet using the Ice Sheet System Model (ISSM)

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