GRACE等低轨卫星通过微波测距观测值和几何轨道以无接触的方式感应地球重力场的变化，在提取地球质量迁移信号方面具有重要的应用，但传统的以球谐位系数表达的时变地球重力场需要进行平滑或滤波的后处理，在过滤噪声的同时不可避免地会过滤掉有用的信号甚至改变信号的空间分布。针对此问题本项目提出对融合MASCON和病态加权总体最小二乘的高精度高分辨率时变地球重力场计算进行深入研究，旨在为GRACE-FO及我国未来卫星重力任务提供技术保障。其基本思路是：对重力卫星关键载荷误差进行详细分析与处理，采取有效的局部参数选择和估计策略，直接以MASCON表示时变地球重力场，建立任意弧段的观测方程，采用完整的随机模型，利用病态加权总体最小二乘计算高精度高时空分辨率地球重力场，通过各种外部数据全面检核其在提取地球质量变化信号的能力，并将其应用于多种局部区域质量迁移信号的计算，探索其对高速铁路潜在沉降区域监测的可能性。

GRACE and other LEO satellites can sense the change of the earth's gravity field through microwave ranging observations and geometric orbits in a non-contact way, which has important applications in extracting the signal of the earth's mass migration. However, the traditional time-varying earth's gravity field expressed by the spherical harmonic coefficients needs to be smoothed or filtered after processing, and the useful signal will inevitably be filtered out while filtering the noise, which will even change the spatial distribution of the signal. In order to solve this problem, this project proposes an in-depth study on the high-precision and high-resolution time-varying gravity field calculation based on MASCON and ill-conditioned weighted total least squares, aiming at providing technical support for GRACE-FO and future satellite gravity missions in China. The basic idea is: to analyze and deal with the key payload errors of gravity satellites in detail, to adopt effective local parameter selection and estimation strategy, to directly represent the time-varying gravity field with MASCON, to establish the observation equation of arbitrary arc section, to adopt complete random model, to calculate the high precision and high spatial-temporal resolution gravity field with ill-conditioned weighted total least squares. All kinds of data are used to check the ability of our method to extract the signals of the earth's mass change, and the method is used to calculate the mass transfer signals in various local areas, so as to explore the possibility of monitoring the potential subsidence areas of high-speed railway.