Thursday 25 August 2005

G2

PTH0052
The downward continuation and simulation experiments
Wang, Zhengtao¹, Shen, WenBin¹, Chao, Dingbo¹
1 Wuhan University, China
Author email: dbchao@sgg.whu.edu.cn
With energy integral approach (e.g., Gerlach et al 2003; Visser et al 2003) one can obtain the Earth's gravitational potential on a simply closed surface (SCS) defined by a flying satellite around Earth. One can determine the Earth's gravitational potential field (EPF) by using either Poisson integral approach or spherical harmonic expansion approach. If the former is applied (with an assumption that the boundary is a spherical surface), there exists the "downward continuation" problem; and if the latter is applied, there exists the "convergence" problem; both of which make geodesists headache. Based on the fictitious compress recovery (FCR) approach (Shen 2004, 2005), EPF in the whole domain outside Earth is uniquely determined once the boundary value of the potential generated by Earth on SCS is given, and consequently the "downward continuation" problem is solved (Shen 2005; Shen et al 2005). To confirm the newly proposed approach, which might be properly called the "fictitious downward continuation" approach (FDCA), various experimental simulation tests are provided, two of which for instance are using the global EGM96 potential field model and the normal potential field model plus an anomaly mass that is assumed buried under ground, respectively. In all cases the potential fields are known and consequently there are known boundary values on SCS. Numerical simulation tests show that FDCA is valid, stable, and satisfactory. With satellite mission observations, practical determination of EPF based on FDCA will be a future research project.

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