基于重力卫星数据监测地表质量变化的三维点质量模型法

Surface mass distribution from gravity satellite observations by using three-dimensional point-mass modeling approach

利用卫星重力测量手段监测全球质量变化取得了巨大成功,本文基于牛顿万有引力定律在三维空间直角坐标系中导出利用重力卫星观测数据监测全球质量变化的三维点质量模型法,该方法可直接利用重力卫星的轨道和星间观测数据或时变重力场模型计算全球质量变化,由于利用卫星观测数据计算地表质量变化的向下延拓过程以及观测数据噪声的影响,需要采用合适的空间约束方程或正则化技术对解算结果进行约束或平滑处理.利用合成全球质量变化模型模拟一个月的GRACE双星轨道和星间距离变率数据计算全球质量变化,对三维点质量模型法进行分析验证,采用零阶Tikhonov正则化技术处理病态问题.结果表明,三维点质量模型法可有效用于重力卫星观测数据监测全球质量变化,为利用重力卫星观测数据监测全球质量变化提供一种可选的途径.

Mass change on the Earth＇s surface derived from gravity satellite data is studied in recent decades. In this study, the three-dimensional point-mass modeling approach （3D-PMA）, a new method expressed in the three-dimensional Cartesian coordinate system, is investigated to detect the Earth＇s surface mass distribution from gravity satellite measurements based on the Newton＇s law of gravitation. Based on this method, the mass distribution could be calculated by directly using gravity satellite orbit and inter-satellite observations or intermediate pseudo-obervation derived from temporal spherical harmonic coefficients. The surface mass distribution computed from the satellite measurements is a downward continuation processing, and at the same time, satellite observations contains noise, so some proper time-space constraint information or regularization techniques are necessarily adopted to stabilize or smooth the solutions. In order to evaluate the performance of the three-dimensional point-mass modeling approach, the mass distribution is computed from one month GRACE-like orbit and K-band range-rate data which is simulated by synthetic global mass change model. The zero-order Tikhonov regularization is used to stabilize the ill-posed inverse problem caused by the downward continuation. The simulation results show that the three-dimensional point-mass modeling approach is an efficacious approach to derive surface mass change from satellite measurements or temporal harmonic solutions. In general, this method provides an alternative way to monitor global mass change by using gravity satellite data.