Separation of mass signals by common inversion of gravimetric and geometric observations

GRACE观测到的质量变化的积分信号是由大气质量变化、海洋变异性、大陆水储存的变化、季节性积雪和冰量变化等因素造成的。确定和区分每个单独过程的贡献是理解大众运输程序的基本要求。本项目将(1)分析能够评估质量变化的地球物理模型，(2)推导出描述这些质量变化的最适当的功能模型，以及(3)通过对所有现有的重力和几何观测进行共同调整来估计这些模型的参数。最后一步是所有精密空间技术的最严格结合，这是考虑到观测和地球物理过程之间的相互依存关系所必需的，而地球物理过程到目前为止常常被忽视：季节性质量变化是从GRACE数据得出的，但不考虑用于卫星跟踪的站的季节性位移。同样，高度计卫星的轨道指的是不包括周期性变化的参照系，但应用测高来得出这种变化。因此，今天发现的质量变化的一部分可能是由于这些几何效应造成的明显影响。本项目旨在通过从重力观测和几何观测的常见反演中分离质量信号来解决这些不一致问题。

The integral signals of mass variations observed by GRACE result, e.g., from atmospheric mass changes, ocean variability, variations in continental water storage, seasonal snow cover and ice volume changes. To identify and separate the contributions of each individual process is a fundamental requirement for understanding the procedure of mass transport. The present project will (i) analyse geophysical models which allow for the assessment of mass variations, (ii) derive the most appropriate functional models to describe these mass variations and (iii) estimate the parameters of these models by a common adjustment of all available gravimetric and geometric observations. The last step, an utmost rigorous combination of all precise space techniques, is necessary to account for the mutual interdependencies between observations and geophysical processes which are up to now often disregarded: seasonal mass variations are derived from GRACE data, but seasonal displacements of stations used for satellite tracking are not accounted for. Similar, the orbits of altimeter satellites refer to a reference system which does not include periodic variations, but altimetry is applied to derive such variations. Thus, parts of the mass variations identified today might be apparent effects due to these geometric effects. The present project aims to solve these inconsistencies by separating mass signals from a common inversion of gravimetric and geometric observations.