A comparison of fixed and freepositioned point mass methods for regional gravity field modeling
 verfasst von
 Miao Lin, Heiner Denker, Jürgen Müller
 Abstract
Radial basis functions (RBFs) have been used widely for regional gravity field modeling. By using the RBFs with the point mass kernel, the RBFbased technique becomes the point mass method. The model setup of the point mass RBFs, consisting of the selection of the spectral bandwidths, depths and network, is crucial for the quality of recovered regional gravity field models. If the spectral bandwidths are defined, the point mass method can be classified into the fixed and freepositioned methods. This study compares the two methods for modeling of regional gravity fields in a unified framework. The fixedpositioned method uses a Reuter grid to determine the RBF number and centers. The grid depth is chosen by experimenting several candidates to achieve the smallest rootmeansquare (RMS) of the differences between predicted and observed values at a set of control points. The magnitudes of the RBFs are estimated by solving a linear equation system, where Tikhonov regularization is applied if the normal matrix is illconditioned. The freepositioned method starts with initially unknown positions of the RBFs, and also the number of RBFs is determined in the computation process. Here, we use a search process to select the RBFs automatically by means of solving a series of nonlinear problems with depth constraints on the RBFs to minimize the RMS difference between the predictions and observations. The magnitudes of all selected RBFs are later reestimated in the leastsquares sense while keeping their positions unchanged. EGM2008 coefficients are firstly used to simulate two harmonic fields to test the performance of the two methods on various Reuter grids, depth limits, and spectral bandwidths, in order to gain certain guidelines for a proper selection of the model parameters. The two methods are then applied to real gravity data sets in the Auvergne and White Sands test areas, respectively. The results reveal that the freepositioned method outperforms the fixedpositioned method in regions with rough gravity field features while using less RBFs. In regions with smooth gravity field features, both methods give similar results, where the fixedpositioned method needs more RBFs than the freepositioned method.
 Organisationseinheit(en)

Institut für Erdmessung
 Typ
 Artikel
 Journal
 Journal of geodynamics
 Band
 125
 Seiten
 3247
 Anzahl der Seiten
 16
 ISSN
 02643707
 Publikationsdatum
 04.2019
 Publikationsstatus
 Veröffentlicht
 Peerreviewed
 Ja
 ASJC Scopus Sachgebiete
 Geophysik, Erdoberflächenprozesse
 Elektronische Version(en)

https://doi.org/10.1016/j.jog.2019.01.001 (Zugang:
Geschlossen)