Surface mass redistribution from joint inversion of GPS site displacements, ocean bottom pressure (OBP) models, and GRACE global gravity models (JIGOG)

在TUD-DEOS、AWI和GFZ之间的合作努力下，我们的目标是制定一种策略，将GPS站点位移、海底压力（OBP）数据、标准和非标准的短期GRACE重力模型的时间序列联合反演为质量传递。虽然大地水准面变化直接或间接地与质量重分布有关，但GPS测点位移通过地球的载荷间接地响应质量通量。先前的研究表明，当每月GRACE解与GPS结合时，GPS可以显著地贡献全球质量再分布的球面谐波，最高可达5度，包括1度。GPS站点在海洋地区是稀疏的，而在大陆地区是不均匀的。结合OBP信息，结合误差方差-协方差、站点分布和GPS和GRACE的个体灵敏度进行联合反演，将在所有空间尺度上提供比仅结合GPS -1度和GRACE更高度的结果更可靠的结果。我们计划优化Kusche和Schrama （2005a,b）开发的逆方法，开发一种互补的区域方法，纳入数值海洋模型的底部压力，研究一致性方面，并验证结果。由于相关的质量变化发生在次月尺度，GFZ将额外贡献非标准短时间（7-10天）GRACE和GRACE/SLR联合重力场解决方案。一个主要的应用将是确定海洋总质量的变化。结合测量到的海洋体积变化，我们将能够确定热膨胀，从而确定全球海洋变暖，其精度远高于常规估算。

In a collaborative effort between TUD-DEOS, AWI and GFZ, we aim at developing a strategy for the joint inversion of time series of GPS site displacements, ocean bottom pressure (OBP) data, and standard and non-standard, short-time GRACE gravity models, into mass transfers. Whereas geoid changes are linked to mass redistributions both directly and indirectly, GPS site displacements respond to mass flux indirectly through loading of the Earth.Previous research has indicated that, when combining monthly GRACE solutions with GPS, GPS could significantly contribute to spherical harmonics of global mass redistribution of up to degree 5, including degree 1. GPS sites are sparse for ocean areas and heterogeneous for continental areas. A joint inversion, accounting for error variance-covariance, site distribution and the individual sensitivities of GPS and GRACE in combination with OBP information, will provide more reliable results on all spatial scales than just combining degree-1 from GPS and higher degrees from GRACE. We plan to optimize the inverse methodology developed by Kusche and Schrama (2005a,b), to develop a complementary regional methodology, to incorporate bottom pressure from numerical ocean models, investigate consistency aspects, and validate results. Because relevant mass variations take place at sub-monthly scales GFZ will additionally contribute with nonstandard short-time (7-10 days) GRACE and GRACE/SLR combined gravity field solutions. A major application will be the determination of variations of the total ocean mass. In conjunction with measured oceanic volume variations we will be able to determine thermal expansion and thus global ocean warming with a much higher accuracy than conventional estimates can provide.