10:45 〜 11:00
[G02-4-02] High-resolution modelling of the static gravity field from the GOCE gravity gradients using meshless boundary collocation techniques
Meshless boundary collocation techniques like the method of fundamental solutions (MFS) or singular boundary method (SBM) can be efficiently used to model the static gravity field purely from the GOCE gravity gradients. These numerical methods use the fundamental solution of the Laplace equation as basis functions. Hence, the system matrix is created by the second radial derivatives of the fundamental solution that depend solely on geometrical parameters, i.e. on 3D positions and direct distances between the GOCE observations and source points located on the Earth's surface. Such a configuration is free of singularities and MFS can be applied to derive unknown coefficients in the source points. From these coefficients the disturbing potential and gravity disturbances can be evaluated in any point above the Earth's surface. To obtain their values directly on the Earth's surface, e.g. at the source points, SBM can be applied. The key idea of SBM is to isolate singularities of the fundamental solution and its derivatives using some appropriate regularization techniques.
The numerical experiments present results of processing several datasets of the GOCE measurements, each for a different semi-annual period. To obtain "cm-level" precision, the source points are regularly distributed over the Earth's surface with the high-resolution of 0.05 deg (12,960,002 points). For every dataset the disturbing gravity gradients as input data are filtered using the nonlinear diffusion filtering. Large-scale parallel computations are performed on the cluster with 1.2 TB of the distributed memory. A combination of numerical solutions obtained for different datasets/periods yields the final static gravity field model which is compared with the SH-based satellite-only geopotential models like GO_CONS_GCF_2_DIR_R5. Finally, the geopotential evaluated on the DTU13 mean sea surface model is used to derive velocities of the ocean geostrophic surface currents.
The numerical experiments present results of processing several datasets of the GOCE measurements, each for a different semi-annual period. To obtain "cm-level" precision, the source points are regularly distributed over the Earth's surface with the high-resolution of 0.05 deg (12,960,002 points). For every dataset the disturbing gravity gradients as input data are filtered using the nonlinear diffusion filtering. Large-scale parallel computations are performed on the cluster with 1.2 TB of the distributed memory. A combination of numerical solutions obtained for different datasets/periods yields the final static gravity field model which is compared with the SH-based satellite-only geopotential models like GO_CONS_GCF_2_DIR_R5. Finally, the geopotential evaluated on the DTU13 mean sea surface model is used to derive velocities of the ocean geostrophic surface currents.