GRACE时变重力场模型精化关键问题研究

The temporal variations of the Earth's gravity field reflect the distribution and transport of mass on and below the Earth’s surface. Observations of the variations in the Earth’s gravity field place important constraints on models of global mass variability and temporal exchange among the land, ocean, and atmosphere. The ll-SST based Gravity Recovery And Climate Experiment (GRACE) mission has provided the most important observations to monitor these variations and has been widely used in Earth sciences. However, the current gravity field solutions still cannot reach the pre-launch baseline accuracy due to the problems including aliasing errors, colored observation noise and intrinsic anisotropy of GRACE and this has greatly limited their application in Earth sciences. To overcome these problems, this proposal will focus and make breakthroughs on the aspects including improved methods of parameterization, refinement of observation stochastic models and multi-data fusion, etc. Precision and resolution of the GRACE time-varying gravity field solutions will be further improved and a new time-series of time-varying gravity field solutions will be produced and released. In the meantime, a complete software system for Earth's gravity field modeling based on the dynamic approach will be well established and can be applicable also to the GRACE Follow-On mission and the gravity satellite mission of our country.

地球时变重力场反映了地球内部及其表面的质量分布与运动，是研究陆地、大气和海洋质量交换及其时空变化的重要约束。基于低低卫星跟踪卫星模式的GRACE重力卫星是监测地球系统质量迁移最为重要的手段，并已在地学领域得到了广泛应用。然而，受限于混频误差、观测值彩色噪声及各向异性等因素，目前GRACE时变重力场反演精度仍未达到设计指标要求，这极大限制了其在地学领域的深入应用。为克服这些问题，本项目将从重力场参数化方法改进、观测值随机模型精化以及多源数据融合等方面进行理论分析及关键技术突破，以进一步提升GRACE时变重力场反演精度和分辨率，解算并发布一套新版地球时变重力场序列。同时，构建一套完备的动力学法地球重力场反演软件系统。相关成果可应用于GRACE Follow-On卫星以及我国的重力卫星任务。

虽然GRACE时变重力场模型在地学领域得到了广泛应用，但较低的精度和空间分辨率极大限制了应用水平。为进一步提升GRACE时变重力场模型的精度和分辨率，项目针对GRACE时变重力场反演中的混频误差、观测值彩色噪声以及各向异性等限制因素，从重力场参数化方法改进、观测值随机模型精化以及多源数据融合等方面进行了理论分析和关键技术突破，进一步改善了模型的精度和分辨率。基于项目研究成果解算了新版GRACE时变重力场模型WHU RL02，并参与了国际时变重力场模型综合COST-G，且模型权重居于各分析中心前列。相关研究成果不但促进了时变重力场模型在地学领域的高水平应用，同时还为我国的重力卫星任务提供了重要支撑。