There remains a significant challenge to model ice crystal fabrics both accurately and efficiently within ice-sheet models. We develop the first fully constrained continuum model, validated against experiments, able to predict the evolution of a crystal fabric for any flow field or temperature. For this, we apply a mesoscopic continuum model describing the evolution of a mass distribution function of c-axis orientations. The model assumes that ice deforms by dislocation creep with slip primarily along the basal plane, and incorporates the effects of rigid-body rotation, migration recrystallization and rotational recrystallization. We solve the model using a new spectral method, which is computationally highly efficient. By constraining the model parameters using data from laboratory experiments in simple shear, we provide the first estimates of the fundamental dimensionless parameters controlling the importance of different deformation and recrystallization processes as functions of temperature, as well as the first constraints on the strain rate dependence of these parameters. With no further fitting, we apply the model to the case of compression, yielding excellent quantitative agreement with observed fabrics from corresponding experiments. The combination of the model, the spectral method and the parameter constraints as functions of temperature provide accurate and efficient predictions of ice crystal fabric evolution for general deformations, temperatures and strain rates. The model-solver (SpecCAF) can, in principle, be extended to other important polycrystalline materials including olivine, the key material in mantle dynamics.

在冰盖模型中准确而有效地对冰晶织物进行建模仍然存在巨大的挑战。我们开发了第一个完全受约束的连续体模型，并通过实验进行了验证，该模型能够预测任何流场或温度下晶体结构的演变。为此，我们应用介观连续体模型来描述c的质量分布函数的演变轴方向。该模型假设冰是由于位错蠕变主要沿基面滑移而变形，并包含了刚体旋转，迁移再结晶和旋转再结晶的影响。我们使用新的频谱方法求解模型，该方法在计算上非常高效。通过使用简单剪切中的实验室实验数据来约束模型参数，我们提供了基本无量纲参数的首次估计，这些基本无量纲参数控制着不同变形和再结晶过程作为温度函数的重要性，以及对应变速率依赖性的第一约束。这些参数。在没有进一步拟合的情况下，我们将模型应用于压缩情况，与来自相应实验的观察到的织物产生了极好的定量一致性。该模型，光谱方法和参数约束作为温度的函数的组合提供了对于一般变形，温度和应变率的冰晶织物演化的准确而有效的预测。原则上，模型求解器（SpecCAF）可以扩展到其他重要的多晶材料，包括橄榄石，这是地幔动力学的关键材料。