Comparison and verification of enthalpy schemes for polythermal glaciers and ice sheets with a one-dimensional model

The enthalpy method for the thermodynamics of polythermal glaciers and ice sheets is tested and verified by a one-dimensional problem (parallel-sided slab). The enthalpy method alone does not include explicitly the transition conditions at the cold-temperate transition surface (CTS) that separates the upper cold from the lower temperate layer. However, these conditions are important for correctly determining the position of the CTS. For the numerical solution of the polythermal slab problem, we consider a two-layer front-tracking scheme as well as three different one-layer schemes (conventional one-layer scheme, one-layer melting CTS scheme, one-layer freezing CTS scheme). Computed steady-state temperature and water-content profiles are verified with exact solutions, and transient solutions computed by the one-layer schemes are compared with those of the two-layer scheme, considered to be a reliable reference. While the conventional one-layer scheme (that does not include the transition conditions at the CTS) can produce correct solutions for melting conditions at the CTS, it is more reliable to enforce the transition conditions explicitly. For freezing conditions, it is imperative to enforce them because the conventional one-layer scheme cannot handle the associated discontinuities. The suggested numerical schemes are suitable for implementation in three-dimensional glacier and ice-sheet models.Comment: 16 pages, 8 figure

Resolution of ice streams and outlet glaciers in large-scale simulations of the Greenland ice sheet

第2回極域科学シンポジウム　共通セッション「大気-海洋-雪氷-固体地球の相互作用」 11月15日（火） 統計数理研究所 3階セミナー室

グリーンランド北西部カナック地域ボードイン氷河の流動に関する数値実験

GRENE北極気候変動研究事業研究成果報告会日時：2016年3月4日（金）　14：30-16：30 (Core time 14：.30-15：40)会場：国立国語研究所　2Fホワイ

Sensitivities of the Antarctic ice sheet/ice shelves on melting and calving around the calving front

第4回極域科学シンポジウム横断セッション：[IP] 極域における多圏融合物理現象11月13日（水）国立極地研究所 ３階 ラウン

Modelling the response of ice sheets to environmental forcing and projecting future sea level rise within the framework of the SeaRISE community effort

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

A continuum-mechanical model for the flow of anisotropic polar ice

In order to study the mechanical behaviour of polar ice masses, the method of continuum mechanics is used. The newly developed CAFFE model (Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor) is described, which comprises an anisotropic flow law as well as a fabric evolution equation. The flow law is an extension of the isotropic Glen's flow law, in which anisotropy enters via an enhancement factor that depends on the deformability of the polycrystal. The fabric evolution equation results from an orientational mass balance and includes constitutive relations for grain rotation and recrystallization. The CAFFE model fulfills all the fundamental principles of classical continuum mechanics, is sufficiently simple to allow numerical implementations in ice-flow models and contains only a limited number of free parameters. The applicability of the CAFFE model is demonstrated by a case study for the site of the EPICA (European Project for Ice Coring in Antarctica) ice core in Dronning Maud Land, East Antarctica.Comment: 12 pages, 11 figures, 1 tabl

Present State and Prospects of Ice Sheet and Glacier Modelling

Since the late 1970s, numerical modelling has become established as an important technique for the understanding of ice sheet and glacier dynamics, and several models have been developed over the years. Ice sheet models are particularly relevant for predicting the possible response of ice sheets to climate change. Recent observations suggest that ice dynamics could play a crucial role for the contribution of ice sheets to future sea level rise under global warming conditions, and the need for further research into the matter was explicitly stated in the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC). In this paper, we review the state of the art and current problems of ice sheet and glacier modelling. An outline of the underlying theory is given, and crucial processes (basal sliding, calving, interaction with the solid Earth) are discussed. We summarise recent progress in the development of ice sheet and glacier system models and their coupling to climate models, and point out directions for future wor

Comparison of thermodynamics solvers in the polythermal ice sheet model SICOPOLIS

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　統計数理研究所 セミナー室2（D304