CSEDI: Core-Mantle Interactions and the Polar Motion of the Earth

CSEDI：核幔相互作用和地球极地运动

• 批准号: 0079998
• 负责人: Weijia Kuang
• 金额: $ 15.2万
• 依托单位: University of Maryland Baltimore County
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0079998&HistoricalAwards=false
• 关键词: CSEDI; Core; Mantle; Interactions; Polar

Weijia Kuang0079998 The investigators plan to expand the Kuang-Bloxham geodynamo model to investigate in detail the dynamical couplings between the Earth's core (including the solid inner core) and its solid mantle, and the angular momentum variation of the solid Earth. They will focus on the equatorial components of the angular momentum that excite the polar motion (variation of the rotation axis of the solid Earth; past studies on this subject have all been dealing with the axial component related to the length-of-day). Geophysical excitations of the "secular" polar motion as well as polar motion of time scales shorter than a few years have been largely understood. On the intermediate time scales, a particularly large undulation known as the Markowitz wobble in the polar motion with a quasi-periodicity of about 30 years and an amplitude as large as 30 milliarcseconds has long been observed but remains a mystery to date. However, the time scale and amplitude of this wobble suggest that the core-mantle coupling may be a possible cause. This project has two parts. First is the modification of the existing 3-dimensional, self-consistent dynamo model to include the hydrostatic elliptic mantle, the hydrostatic elliptic solid inner core and the couplings of the solid Earth. Then, the investigators will use the modified geodynamo model to evaluate core-mantle interactions within the geodynamo simulation. Of particular interest, they plan to investigate the contributions of electromagnetic, topographic and gravitational (between the inner core and the mantle) energy on the equatorial angular momentum exchange between the core and mantle. The proposed research shall be carried out among the PI, Dr. Weijia Kuang, at the University of Maryland, Baltimore County (leading effort in geodynamo simulation) and collaborators Dr. Lanbo Liu of the University of Connecticut (mantle structure and dynamics) and Dr. Benjamin Chao of NASA's Goddard Space Flight Center (Earth rotation dynamics).

研究人员计划扩展Kuang-Bloxham地球动力学模型，详细研究地核（包括固体内核）与固体地幔之间的动力学耦合以及固体地球的角动量变化。他们将把重点放在激发极地运动的角动量的赤道分量上（固体地球旋转轴的变化；过去对这个主题的研究都是处理与一天的长度有关的轴向分量）。“长期”极运动的地球物理激励以及短于几年的时间尺度的极运动已经在很大程度上得到了理解。在中间时间尺度上，在极运动中有一种被称为马科维茨摆动的特别大的波动，其准周期约为30年，振幅可达30毫弧秒，长期以来一直被观察到，但至今仍是一个谜。然而，这种摆动的时间尺度和幅度表明，地核-地幔耦合可能是一个可能的原因。这个项目有两个部分。首先是对现有的三维自洽发电机模型进行修正，使其包括静压椭圆型地幔、静压椭圆型固体内核和固体地球的耦合。然后，研究人员将使用改进的地球动力模型来评估地球动力模拟中的核-幔相互作用。特别感兴趣的是，他们计划研究电磁、地形和重力（在内核和地幔之间）能量对核心和地幔之间赤道角动量交换的贡献。拟议的研究将在PI，马里兰大学巴尔的摩分校的Weijia Kuang博士（地球动力学模拟的领导工作）和康涅狄格州大学的Lanbo Liu博士（地幔结构和动力学）和美国宇航局戈达德太空飞行中心的Benjamin Chao博士（地球自转动力学）之间进行。