地球主惯性矩的精密确定及三轴分层地球自转动力学研究

Precise Determination of the Earth's Principal Moment Inertia and Study of Tri-axial Layered Earth Rotation Dynamics

该研究目标是利用重力场模型精确确定地球主惯性矩及其时变性,基于高精度地球主惯性矩建立三轴分层地球自转理论,更精确地描述地球自转状态,研究地球自转规律,特别是三轴分层地球自转及其对物质迁移的响应,揭示地球自转、物质迁移与全球变化、地球动力学事件和重大自然灾害的关联,为精化地球参考系、航天器高精度定位定向以及相关学科研究提供支持,揭示地球系统物质迁移动力学机理。根据任务计划安排及研究进展的实际情况,该年度取得的主要研究进展有:基于GRACE重力卫星观测数据,利用短弧长法成功解算出全球时变重力场模型(IGG-CAS系列模型),优于RL04模型,但比RL05略差;进一步完善了确定地球主惯性矩的理论模型,并利用重力场模型及时变重力场模型精确确定了地球主惯性矩及其时变性;建立了一组联合大气、海洋和陆地水模型(数据),显著改进了大气、海洋和陆地水对极移的激发作用;在地球极移激发中考虑了地球的频率依赖响应,计算结果表明,考虑了频率依赖响应和滞弹性之后可以更好地解释地球的极移激发。

Study on precise determination of the earth's principal moments of inertia and tri-axial layered Earth rotation dynamic is the fifth topic of 973 project of “the Study on high resolution and accuracy of static and time-variable Earth gravity field and its dynamics”. The research aim of this topic is to use gravity field models to determine the Earth's principal moments of inertia and its changes, establish a tri-axial layered Earth rotation theory based on precisely determined Earth's principal moments of inertia, more precisely describe the Earth rotation status, study Earth rotation laws and rules, especially the response of tri-axial layered Earth rotation due to mass migration, reveal the relation among the Earth rotation, mass migration and global change, geodynamics events and significant natural disasters, in order to provide basic information for Earth reference system refinement, space craft positioning and orientation with high accuracy, and other science research branches,reveal the dynamic mechanism of the Earth’s system mass migration. According to the project plan arrangement and research development in practice, the main achievements obtained in this year are stated as follows: Using short-arc approach, the first version of the temporal gravity field model series IGG-CAS was successfully established in this year based upon GRACE data, and the IGG-CAS model is better than the RL04, but worse than RL05; we further refined a theoretical model for determining the Earth’s principal moments of inertia, and determined the Earth’s principal moments of inertia and their temporal variations; combining the current atmospheric, oceanic and land-water models, we established a joint model which could significantly improve the excitation response of the polar motion; further, we considered the frequency dependence response in the excitation of polar motion, and it demonstrates that the results with considering the frequency dependence response and elasticity of the Earth can better explain the excitation of the polar motion. Supported by the project (No.2013CB733305), 10 relevant papers were published or accepted, including 8 SCI papers.