GRACE与GRACE Follow-On无缝衔接关键技术研究

GRACE卫星时变重力场在监测全球地表质量变化等方面具有重要作用，而末期GRACE卫星在数据质量及连续性、与将来GRACE Follow-On卫星的衔接等方面存在潜在问题。项目围绕GRACE与GRACE Follow-On无缝衔接的关键技术展开研究，研究内容：（1）研究基于低轨卫星几何轨道及方差信息的经典动力学法的改进理论，即直接以低轨卫星几何轨道为初值对经典动力学法的函数模型进行线性化，构建实用的数学模型；（2）分析多源低轨卫星几何轨道误差随机特性，精化观测值随机模型，分析不同观测值反演时变重力场的有效频段，并确定不同观测值最优相对权比，以实现多源低轨卫星几何轨道的最优融合；（3）研制高效并行计算软件；（4）融合多源低轨卫星几何轨道反演GRACE与GRACE Follow-On衔接空白时间段的时变重力场，并对模型空间分辨率及精度进行评定。本项目可确保全球大尺度地表质量变化的连续监测。

Although GRACE time-variable gravity fields play an important role in monitoring mass redistribution within the Earth system, there are still potential challenges such as quality and continuity, and the gap between GRACE and GRACE follow-on at the end of GRACE mission. This project studies on the key technology on seamless connection of GRACE and GRACE Follow-on mission. The key research contents:(1) The theory of improved dynamics method is investigated based on kinematic positions of low Earth orbiters(LEOs) and variance information, the mathematical model of improved dynamics method is carried out linearization with respect to the kinematic orbit, and practical mathematical models are also developed; (2) In order to realize the optimal fusion of kinematic positions of multiple LEOs, the error random characteristics of kinematic orbit are analyzed, the random model of observations is refined, the effective frequency band of gravity field inversion for different observations is analyzed, and the optimal relative weight ratio of different observations is determined;(3) The efficient parallel computing software is developed；(4)The gap of time-variable gravity between GRACE and GRACE Follow-On is filled with kinematic positions of multiple LEOs, the spatial resolution and accuracy of the time-variable gravity model are estimated. Finally the continuous monitoring of the global change of the earth's surface mass at large scale is realized.