Genauigkeitssimulation von Schwerefeld-Satellitenmissionen

This thesis deals with an analysis of a simulator for gravity field determination from space borne observations. The theory behind it is a semi-analytical approach, in which the satellite orbit is defined as a circular orbit with constant inclination. Because of these simplifications the key formular of this approach results from the transformation of the gravity potential, which is developed into spherical harmonics on the sphere, into the reference frame, which moves with the satellite. This formular contains the lumped coefficients which appear as 2D Fourier coefficients. The parameters of the Fourier series, which is associated with these coefficients, are the basic coordinates of the satellite orbit. These are the argument of latitude and the longitude of the ascending node. The lumped coefficients are a linear combination of the transfer coefficients and the spherical harmonic coefficients. The design matrix of a least squares estimation system consists of these transfer coefficients. The associated weight matrix is being calculated from the power spectral densities (PSD) of the observation noise. These PSDs have to be detected for the observation frequencies, which are normalized by the orbit frequency. Thus one gets a normal equation system from which, by inverting it, the variances and covariances of the spherical harmonic coefficients can be estimated. This thesis starts with explaining the theoretical context of the simulator. It leads through the various elements step by step. A short instruction is included as well. After a validation variations of the starting parameters will be analysed. Eventually upgrade options will be discussed. The appendix contains several case studies which also include combinations of gravity field satellite missions.     «

This thesis deals with an analysis of a simulator for gravity field determination from space borne observations. The theory behind it is a semi-analytical approach, in which the satellite orbit is defined as a circular orbit with constant inclination. Because of these simplifications the key formular of this approach results from the transformation of the gravity potential, which is developed into spherical harmonics on the sphere, into the reference frame, which moves with the satellite. This form...     »