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Modeling ice streams.

机译：模拟冰流。

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摘要

Modeling glacier and ice sheet flow is a computationally challenging problem. The most challenging part in simulating ice sheet flow is modeling the fastest moving part of ice sheets, ice streams. In the first part of the thesis, we have constructed two numerical models of isothermal ice stream flow, a three-dimensional full-Stokes ice-sheet/ice-stream/ice-shelf model and a modified MacAyeal-Morland ice-stream/ice-shelf model. In the second part of the thesis, we studied the possibility of using SuperLU-DIST multiprocessor software package for solving the systems of linear equations generated by the model.;The uniqueness of the modified MacAyeal-Morland model is in its inclusion of the basal shear friction in the derivation of the equations. In the original MacAyeal-Morland equations, the shear friction is not included in the fundamental formulation but instead is added as a small correction to the final equations. Inclusion of the basal friction in the derivation generates equations that contain a term that depends on the bed gradients; that is, it generates equations that show how the ice stream flow may depend on the bed topography. To validate the model, the European Ice Sheet Modeling Initiative 1 intercomparison test is conducted and the results are compared with the results generated by MacAyeal (1994).;The three-dimensional full-Stokes model includes all higher-order stress gradients in the force-balance equation. To validate the full-Stokes model, experiments demonstrating the importance of the inclusion of all higher order stresses in the model, such as simulation of the evolution of an ice stream within the ice sheet and simulation of iceberg profiles, are conducted.;The computational demands of the full-Stokes model do not allow us using it in large problem domains. To solve this problem, application of SuperLU-DIST multiprocessor software package has been examined. The software's performance characteristics have been explored and benchmarked on the matrices generated by the three-dimensional full-Stokes model. The performed tests indicate that for the big-size matrices computations may not be stable. However, we have shown that it is possible to improve stability of the algorithm by using a priori knowledge of the matrix and permuting rows prior to applying the algorithm.
机译：对冰川和冰盖流动进行建模是一个计算难题。模拟冰原流动中最具挑战性的部分是对冰原运动最快的部分-冰流进行建模。在论文的第一部分，我们建立了两个等温冰流的数值模型，一个三维全斯托克斯冰盖/冰流/冰架模型和一个改进的MacAyeal-Morland冰流/冰模型。 -货架模型。在论文的第二部分中，我们研究了使用SuperLU-DIST多处理器软件包来求解该模型所生成的线性方程组的可能性。方程推导中的摩擦。在原始的MacAyeal-Morland方程中，基本公式中不包括剪切摩擦，而是将其作为对最终方程的较小修正而添加。在推导中包含基础摩擦会生成方程，其中包含一个取决于床坡度的项。也就是说，它生成的方程式表明冰流的流量如何取决于床的地形。为了验证该模型，进行了欧洲冰盖模型倡议1的比对测试，并将结果与​​MacAyeal（1994）生成的结果进行了比较。三维全斯托克斯模型包括力中所有高阶应力梯度平衡方程。为了验证全斯托克斯模型，进行了表明所有高阶应力都包含在模型中的重要性的实验，例如模拟冰盖内冰流的演化和模拟冰山剖面。 Full-Stokes模型的需求不允许我们在较大的问题域中使用它。为了解决这个问题，已经研究了SuperLU-DIST多处理器软件包的应用。该软件的性能特征已经在三维全Stokes模型生成的矩阵上进行了探索和基准测试。进行的测试表明，对于大尺寸矩阵，计算可能不稳定。但是，我们已经表明，可以通过使用矩阵的先验知识和在应用算法之前对行进行置换来提高算法的稳定性。

著录项

  • 作者

    Sargent, Aitbala.;

  • 作者单位

    The University of Maine.;

  • 授予单位 The University of Maine.;
  • 学科 Geology.;Computer Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 145 p.
  • 总页数 145
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;自动化技术、计算机技术;
  • 关键词

  • 入库时间 2022-08-17 11:38:29

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