Planetary Mantle Dynamics

太阳系中类地行星的热损失是由它们外层硅酸盐壳中的对流控制的。就地球而言，这种对流表现为板块构造和由此产生的大陆漂移。本提案所包含的研究将集中在行星内部的热演化以及表面和内部动力学之间的反馈。该方法将侧重于利用计算机模型的二维和三维对流流体包含在自重力球壳或平面层系统。提出大量活动的动机源于这样一种观察：地球是太阳系中唯一具有板块构造特征的行星，我们渴望理解为什么会这样。具体感兴趣的主题将包括检查系统几何形状（即地幔厚度），特别是行星核心大小对地幔对流热特性的影响。此外，我们将研究活动表面对地幔对流的影响以及板块运动的物理条件。通过研究流体参数（如热粘度依赖性）对对流特性的影响，将探索岩石行星和冰卫星热演化的本质。此外，大陆和深层化学异常可能在行星热演化中发挥的作用将推动部分拟议的工作。还将研究模型的扩展及其在系外行星上的应用。利用在分布式内存并行计算平台上运行的复杂计算模型（即利用许多处理器）促进了研究。目前，一个由四名研究生组成的小型行星内部小组在我的指导下在多伦多大学斯卡伯勒分校（UTSC）工作，并受益于sciet通用计算（GPC）集群。在过去的五年中，研究小组已经将所有用于我们研究的计算机代码迁移到SciNet的GPC上。因此，这里提出的研究所需的所有工具都已经可用，经过测试并准备使用。此外，我们现在正在利用UTSC开发的代码以及从合作企业获得的新计算机代码，这些代码非常适合利用SciNet的能力。这将使这里描述的研究项目能够在制度和时间尺度上探索物理行为，这是以前无法实现的。例如，现在可用的代码和高性能计算设备将使UTSC的研究人员能够模拟具有对流活力和类地行星表面面积的系统中的行星对流，模拟数十亿年的进化周期。所有这些研究的基本主题是调查行星热损失和表面运动的时间依赖性。所涉及的研究将培养高素质的人员（HQP）使用高性能计算来研究地球物理流体动力学问题。为进行这些项目，需要为一个由六名研究人员组成的小组提供支持。在未来五年内，该小组的总体构成将包括一名首席研究员，一名博士后研究助理和四名研究生，从事硕士和博士研究。这些HQP将参与国际合作研究，使用研究所需的计算工具。资金将支持他们完成6个博士学位和4个硕士学位，HQP将完成他们的研究项目，其中包括作为地球动力学家的培训和了解科学成果传播的方法。

Heat loss from the terrestrial planets in our solar system is governed by convection in their outer silicate shells. In the case of the Earth, this convection is manifested as plate tectonics and the continental drift that results. The research encompassed in this proposal will focus on the thermal evolution of planetary interiors and the feedback between surface and interior dynamics. The methodology will focus on utilizing computer models of two- and three-dimensional convecting fluids contained within either self-gravitating spherical shells or plane-layer systems. Motivation for a substantial amount of the proposed activity derives from the observation that the Earth is the only planet in the solar system featuring plate tectonics and our desire to understand why this is so. Specific topics of interest will include examining the influence of system geometry (i.e., mantle thickness) and particularly planetary core size on the thermal character of mantle convection. In addition, we shall investigate the influence of a mobile surface on mantle convection as well as the physical requirements for plate motion. The nature of the thermal evolution of rocky planets and icy moons will be explored by investigating the influence of fluid parameters (e.g., thermal viscosity dependence) on convection characteristics. Moreover, the role in planetary thermal evolution that may be played by continents and deep chemically distinct anomalies will drive a portion of the proposed work. Extension of the models and applications to exosolar planets will also be examined. The research is facilitated by utilizing sophisticated computational models run on distributed memory parallel computing platforms (i.e., utilizing many processors). Presently, a small planetary interiors group of four graduate students works under my guidance at the University of Toronto-Scarborough (UTSC) and benefits from access to the SciNet General Purpose Computing (GPC) Cluster. Over the past five years the research group has migrated all of the computer codes used for our research to SciNet's GPC. Consequently, all tools required for the research proposed here are already available, tested and ready to use. In addition, we are now utilizing codes developed at UTSC as well as new computer codes, obtained from collaborative ventures that are well suited to capitalize on SciNet's capabilities. This will enable the research projects described here to probe physical behaviour in regimes, and on time-scales, not previously accessible. For example, the codes and high performance computing facilities now available will allow researchers at UTSC to model planetary convection in systems featuring both the convective vigour and the surface area of an Earth-like planet over periods simulating billions of years of evolution. The underlying theme of all of these studies is investigation of the time-dependence of planetary heat loss and surface motion. The research involved will train highly qualified personnel (HQP) in the use of high performance computing for investigating problems in geophysical fluid dynamics. To undertake these projects , support for a group of six researchers is sought. Over the next five years, the general makeup of this group will include the Principal Investigator, a post-doctoral research assistant and four graduate students, engaged in both MSc and PhD studies. These HQP will be engaged in international collaborative research stemming from use of the computing tools required for the research. Funding would support the completion of six PhD and four MSc degrees and the HQP will complete their research projects having obtained experience that will include training as geodynamicists and exposure to the methods by which scientific results are disseminated.