Review of "The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet"

2018 ◽  
Author(s):  
Anonymous
Keyword(s):  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Calibration And Validation ◽  
Model Version ◽  
Version 2.0 ◽  
The Antarctic

scholarly journals The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet

2018 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas ◽  
Catherine Ritz ◽  
Vincent Peyaud ◽  
Didier M. Roche
Keyword(s):  
Ice Sheet ◽  
Climate Forcing ◽  
Antarctic Ice Sheet ◽  
Ice Volume ◽  
Grounding Line ◽  
Version 2.0 ◽  
The Antarctic ◽  
Climate Proxies ◽  
Ice Model

Abstract. In this paper we present the GRISLI (Grenoble Ice Sheet and Land Ice) model in its newest revision (version 2.0). Whilst GRISLI is applicable to any given geometry, we focus here on the Antarctic ice sheet because it highlights the importance of grounding line dynamics. Important improvements have been implemented since its original version (Ritz et al., 2001) including notably an explicit flux computation at the grounding line based on the analytical formulations of Schoof (2007) and Tsai et al. (2015) and a basal hydrology model. A calibration of the mechanical parameters of the model based on an ensemble of 150 members sampled with a Latin Hypercube method is used. The ensemble members performance is assessed relative to the deviation from present-day observed Antarctic ice thickness. The model being designed for multi-millenial long- term integrations, we also present glacial-interglacial ice sheet changes throughout the last 400 kyr using the best ensemble members. To achieve this goal, we construct a simple climatic perturbation of present-day climate forcing fields based on two climate proxies, both atmospheric and oceanic. The model is able to reproduce expected grounding line advances during glacials and subsequent retreats during terminations with reasonable glacial-interglacial ice volume changes.

scholarly journals The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet

2018 ◽  
Vol 11 (12) ◽  
pp. 5003-5025 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas ◽  
Catherine Ritz ◽  
Vincent Peyaud ◽  
Didier M. Roche
Keyword(s):  
Ice Sheet ◽  
Climate Forcing ◽  
Method Performance ◽  
Antarctic Ice Sheet ◽  
Grounding Line ◽  
Version 2.0 ◽  
Glacial Periods ◽  
The Antarctic ◽  
Climate Proxies

Abstract. In this paper, we present the GRISLI (Grenoble ice sheet and land ice) model in its newest revision (version 2.0). Whilst GRISLI is applicable to any given ice sheet, we focus here on the Antarctic ice sheet because it highlights the importance of grounding line dynamics. Important improvements have been implemented in the model since its original version (Ritz et al., 2001). Notably, GRISLI now includes a basal hydrology model and an explicit flux computation at the grounding line based on the analytical formulations of Schoof (2007) or Tsai et al. (2015). We perform a full calibration of the model based on an ensemble of 300 simulations sampling mechanical parameter space using a Latin hypercube method. Performance of individual members is assessed relative to the deviation from present-day observed Antarctic ice thickness. To assess the ability of the model to simulate grounding line migration, we also present glacial–interglacial ice sheet changes throughout the last 400 kyr using the best ensemble members taking advantage of the capacity of the model to perform multi-millennial long-term integrations. To achieve this goal, we construct a simple climatic perturbation of present-day climate forcing fields based on two climate proxies: atmospheric and oceanic. The model is able to reproduce expected grounding line advances during glacial periods and subsequent retreats during terminations with reasonable glacial–interglacial ice volume changes.

scholarly journals A Joint Inversion Estimate of Antarctic Ice Sheet Mass Balance Using Multi-Geodetic Data Sets

2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi
Keyword(s):  
Mass Balance ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Mass Change ◽  
West Antarctica ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
Uplift Rates ◽  
The Antarctic

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.

scholarly journals Characteristics of the Antarctic Ice-Sheet

Nature ◽  
1959 ◽  
Vol 183 (4675) ◽  
pp. 1575-1577 ◽  
Author(s):  
T. F. GASKELL
Keyword(s):  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
The Antarctic
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