An ice sheet model of reduced complexity for paleoclimate studies

Neff, Basil; Born, Andreas; Stocker, Thomas F.

doi:10.5194/esd-7-397-2016

Cited by 5 publications

(6 citation statements)

References 102 publications

(148 reference statements)

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“…The model includes all dynamical components to represent the full 3-D flow in future applications. Most of the necessary infrastructure, including a 2-D horizontal grid, has already been developed in parallel to the isochronal model in a second ice-sheet model (Neff and others, 2016).…”

Section: Discussionmentioning

confidence: 99%

Tracer transport in an isochronal ice-sheet model

Born

2016

J. Glaciol.

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ABSTRACT. The full history of ice sheet and climate interactions is recorded in the vertical profiles of geochemical tracers in polar ice sheets. Numerical simulations of these archives promise great advances both in the interpretation of these reconstructions and the validation of the models themselves. However, fundamental mathematical shortcomings of existing models subject tracers to spurious diffusion, thwarting straightforward solutions. Here, I propose a new vertical discretization for ice-sheet models that eliminates numerical diffusion entirely. Vertical motion through the model mesh is avoided by mimicking the real-world flow of ice as a thinning of underlying layers. A new layer is added to the surface at equidistant time intervals, isochronally, thus identifying each layer uniquely by its time of deposition and age. This new approach is implemented for a two-dimensional section through the summit of the Greenland ice sheet. The ability to directly compare simulations of vertical ice cores with reconstructed data is used to find optimal model parameters from a large ensemble of simulations. It is shown that because this tuning method uses information from all times included in the ice core, it constrains ice-sheet sensitivity more robustly than a realistic reproduction of the modern ice-sheet surface.

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Section: Discussionmentioning

confidence: 99%

Tracer transport in an isochronal ice-sheet model

Born

2016

J. Glaciol.

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“…The experiments use a modification of the two-dimensional vertically isothermal IceBern2D ice sheet model described in [12]. The original version of the model was characterized by an excessively strong growth of ice sheets near mountain ranges, including at the boundary of the computational domain.…”

Section: The Model Of Ice Sheets In Use and Numerical Experimentsmentioning

confidence: 99%

Impact of the uncertainty of reconstruction of climate changes in the last glacial cycle on modelling of ice sheets dynamics

Ploskov,

Eliseev,

Mokhov

2023

29th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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Ensemble (taking into account the uncertainty of climatic paleoreconstructions) numerical experiments were carried out with a model of ice sheet dynamics for the last glacial cycle (128 thousand years) in the Northern Hemisphere. The model, as a whole, adequately reproduces the spatial distribution of ice sheets and the height of their domes and corresponding ocean level changes. When perturbed with a sufficiently large amplitude of paleoclimatic data, the model reveals significant differences in the results of modeling the ice sheets from those obtained for the initial paleoreconstruction, including for the period of the last glacial maximum and for the time interval 58-51 thousand years ago (the initial part of MIS3). According to the experiments results, the uncertainty of global reconstructions for the last glacial cycle is 2°C, which is consistent with the available estimates.

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“…Each horizontal axis has 313 grid cells. This grid is identical to the one used in the fast ice sheet model IceBern2D, into which BESSI is integrated as a subroutine (Neff et al, 2016). However, ice dynamics are disabled in all simulations shown here.…”

Section: Model Domain and Discretizationmentioning

confidence: 99%

“…BESSI is implemented in FORTRAN90 as a subroutine of the ice sheet model IceBern2D (Neff et al, 2016). The decision tree and calculation flow at each time step is shown in Fig.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…The interface for this coupling between ice and climate is provided by surface mass balance (SMB) models of different complexities, ranging from empirical temperature index models, also known as positive degree day (PDD) models (Reeh, 1991;Ohmura, 2001), to comprehensive physical energy balance models that resolve the snow surface at millimetre scale and with an evolving snow grain microstructure (Bartelt and Lehning, 2002). While empirical models that calculate the mass balance from fields of air temperature and precipitation alone perform adequately in specific regions and stable climate (Hock, 2003), their results become unreliable for large regions with spatially heterogenic and temporally varying climatic conditions (Bougamont et al, 2007;Robinson and Goelzer, 2014;Gabbi et al, 2014;Plach et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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

2019

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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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An ice sheet model of reduced complexity for paleoclimate studies

Cited by 5 publications

References 102 publications

Tracer transport in an isochronal ice-sheet model

Tracer transport in an isochronal ice-sheet model

Impact of the uncertainty of reconstruction of climate changes in the last glacial cycle on modelling of ice sheets dynamics

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

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