Comparison of surface mass balance of ice sheets simulated by positive-degree-day method and energy balance approach

Bauer, Eva; Ganopolski, Andrey

doi:10.5194/cp-13-819-2017

Cited by 34 publications

(38 citation statements)

References 61 publications

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“…In the aforementioned papers the ice sheet tends to be limited to the western/northwestern side of the North American continent (e.g., Charbit et al, 2013;Beghin et al, 2014), little or no ice is established in western Eurasia (e.g., Charbit et al, 2013;Beghin et al, 2014), and attempts to remedy these shortcomings typically result in substantial ice formation in Siberia and Alaska (see Charbit et al, 2013, who tested the sensitivity of the same PDD-based SMB parameterizations as were used in this study). These results appear to be largely independent of both the choice of ice sheet model (the above studies used SICOPOLIS and GRISLI), and the complexity of the SMB parameterization (Charbit et al, 2013;Bauer and Ganopolski, 2017). Although it is not completely fair to compare CLIMBER-2 to a low resolution version of CAM3 (the complexity and general purpose of these models are extremely different), it is possible that these similarities demonstrate a fundamental problem with low-resolution climate models that transcends model complexity.…”

Section: Discussionmentioning

confidence: 95%

The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

Löfverström

Liakka

2018

The Cryosphere

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Abstract. Coupled climate-ice sheet simulations have been growing in popularity in recent years. Experiments of this type are however challenging as ice sheets evolve over multimillennial timescales, which is beyond the practical integration limit of most Earth system models. A common method to increase model throughput is to trade resolution for computational efficiency (compromise accuracy for speed). Here we analyze how the resolution of an atmospheric general circulation model (AGCM) influences the simulation quality in a stand-alone ice sheet model. Four identical AGCM simulations of the Last Glacial Maximum (LGM) were run at different horizontal resolutions: T85 (1.4 • ), T42 (2.8 • ), T31 (3.8 • ), and T21 (5.6 • ). These simulations were subsequently used as forcing of an ice sheet model. While the T85 climate forcing reproduces the LGM ice sheets to a high accuracy, the intermediate resolution cases (T42 and T31) fail to build the Eurasian ice sheet. The T21 case fails in both Eurasia and North America. Sensitivity experiments using different surface mass balance parameterizations improve the simulations of the Eurasian ice sheet in the T42 case, but the compromise is a substantial ice buildup in Siberia. The T31 and T21 cases do not improve in the same way in Eurasia, though the latter simulates the continent-wide Laurentide ice sheet in North America. The difficulty to reproduce the LGM ice sheets in the T21 case is in broad agreement with previous studies using low-resolution atmospheric models, and is caused by a substantial deterioration of the model climate between the T31 and T21 resolutions. It is speculated that this deficiency may demonstrate a fundamental problem with using low-resolution atmospheric models in these types of experiments.

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Section: Discussionmentioning

confidence: 95%

The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

Löfverström

Liakka

2018

The Cryosphere

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“…Then we ran a set of offline simulations in which, similarly to Bauer and Ganopolski (2017), the climate and ice sheets are prescribed from the reference simulation and the surface mass balance is diagnosed for experiments with different surface albedo set-ups. To separate the importance of snow aging and dust on snow albedo, we ran offline experiments with and without snow aging and with and without the effect of aeolian and glaciogenic dust sources on snow albedo.…”

Section: Methodsmentioning

confidence: 99%

The importance of snow albedo for ice sheet evolution over the last glacial cycle

Willeit

Ganopolski

2018

Clim. Past

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Abstract. The surface energy and mass balance of ice sheets strongly depends on the amount of solar radiation absorbed at the surface, which is mainly controlled by the albedo of snow and ice. Here, using an Earth system model of intermediate complexity, we explore the role played by surface albedo for the simulation of glacial cycles. We show that the evolution of the Northern Hemisphere ice sheets over the last glacial cycle is very sensitive to the representation of snow albedo in the model. It is well known that the albedo of snow depends strongly on snow grain size and the content of lightabsorbing impurities. Excluding either the snow aging effect or the dust darkening effect on snow albedo leads to an excessive ice build-up during glacial times and consequently to a failure in simulating deglaciation. While the effect of snow grain growth on snow albedo is well constrained, the albedo reduction due to the presence of dust in snow is much more uncertain because the light-absorbing properties of dust vary widely as a function of dust mineral composition. We also show that assuming slightly different optical properties of dust leads to very different ice sheet and climate evolutions in the model. Conversely, ice sheet evolution is less sensitive to the choice of ice albedo in the model. We conclude that a proper representation of snow albedo is a fundamental prerequisite for a successful simulation of glacial cycles.

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“…It is computationally expensive to do this due to the long time period of simulations. Alternatively, an approach of coupling ice sheet models to Earth system Models of Intermediate Complexity (EMICs, Claussen et al, 2002) 15 has been used (e.g., Charbit et al, 2005;Ganopolski et al, 2010;Bauer and Ganopolski, 2017), while the missing processes in EMICs may also have large effects on regional ice sheet distributions. Another approach for long-term ice sheet simulations is by using time slice simulations at the LGM or present day, and interpolating between them by using the…”

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confidence: 99%

Sensitivity of atmospheric forcing on Northern Hemisphere ice sheets during the last glacial-interglacial cycle using output from PMIP3

Niu

Lohmann

Hinck

et al. 2017

Preprint

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Abstract. We use the three-dimensional Parallel Ice Sheet Model (PISM) to simulate Northern Hemisphere ice sheets evolution through the last glacial-interglacial cycle. The simulation is driven by the NGRIP 18O index combined with climate forcing at two time slices, the Last Glacial Maximum (LGM) and present day (PD). In order to investigate the sensitivity of the ice sheets to the atmospheric forcing, atmospheric output from nine climate models from the Paleoclimate ModelingIntercomparison Project Phase III (PMIP3) are used to force the ice sheet model with the same set-up. The results show large 5 diversity in simulated ice sheets between different models. By comparing the atmospheric forcing, we found that summer surface air temperature pattern resembles the ice sheet extent pattern at the LGM, which shows great sensitivity to summer surface air temperature. This implies that careful constrains on climate output is essential for simulating reliable glacial-interglacial Northern Hemisphere ice sheets. The ablation process is of vital importance for high-latitude Northern Hemisphere ice sheets.Besides, the absent nonlinear interactions between ice sheet and atmosphere and ocean, which have different signals regionally, 10 also contribute to the mismatches between simulated ice sheets and geological evidences. Hence, we highlight the needs for coupling an ice sheet model to GCM to take into account these missing processes.

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Comparison of surface mass balance of ice sheets simulated by positive-degree-day method and energy balance approach

Cited by 34 publications

References 61 publications

The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

The importance of snow albedo for ice sheet evolution over the last glacial cycle

Sensitivity of atmospheric forcing on Northern Hemisphere ice sheets during the last glacial-interglacial cycle using output from PMIP3

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