利用GNSS固体潮位移观测数据研究深地幔侧向不均匀性结构特征

对固体潮形变的观测与研究是了解地球内部结构的重要手段。申请人的前期研究表明全球导航卫星系统（Global Navigation Satellite System，GNSS）观测技术能提供水平精度达0.1mm和垂向精度达0.3mm的三维固体潮位移形变，发现了地球结构侧向不均匀性是引起亚毫米量级的大尺度地表固体潮位移变化的主要因素，这为约束地球深内部三维结构提供了全新的观测数据。本项目拟开展基于地球自由振荡简正模的固体潮位移计算理论和方法研究，利用GNSS实测固体潮位移数据反演深地幔大尺度三维密度和弹性结构参数，分析深地幔侧向不均匀性结构变化特征。本项目研究不仅可为现代大地测量和地球物理观测提供顾及地球结构侧向不均匀性的高精密固体潮形变改正模型，而且为揭示地球深内部结构与物质组成、地幔对流的动力机制及其动力演化提供重要的观测约束。

Observation and investigation of body tide deformation is an important means to constrain the interior structure of the Earth. Our latest study showed that Global Navigation Satellite System (GNSS) measurements provide 3-D body tide displacement field accurate to the level of 0.1 mm (horizontal) and 0.3 mm (vertical) for the lunar-only constituents, and reveal deficiencies of the a priori 1-D body tide modeling in catching lateral heterogeneity in the Earth's deep mantle structure, thus providing a novel data set for constraining deep mantle density and elastic structure. This project proposes to develop the theory and method of body tide displacement calculation based on the normal mode of the Earth's free oscillations, explore the methodology of inversing the large-scale 3-D density and elastic structural parameters of in the Earth's deep mantle derived from global GNSS measurements of body tide deformation, and analyze the structural characteristics of lateral heterogeneity of the deep mantle. This project will not only provide a high-precision body tide deformation correction model that takes into account the Earth's lateral inhomogeneity for modern geodesy and geophysical observations, but also provide important observational constraints on the thermal and/or compositional heterogeneity of Earth's deep mantle, the dynamic mechanism of mantle convection and the long-term evolution of the Earth system.