Master´s thesis defense by Mille Lærke Nielsen – Niels Bohr Institute - University of Copenhagen

Forward this page to a friend Resize Print kalender-ikon Bookmark and Share

Niels Bohr Institute > Calendar > Activities 2013 > Master´s thesis defens...

Master´s thesis defense by Mille Lærke Nielsen






Regional Modeling  of the Geomagnetic Field - by Equivalent Sources

Abstract
In this master thesis the geomagnetic crustal field around Neumayer station at Antarctica is mapped by two different methods; a sequential solution and a coestimation solution. A crustal field model is created with equivalent sources. The equivalent sources are placed in a lattice in the crust and a field strength is calculated from the data.

Noise in the data is removed by a single-line linear detrending or multiple-line detrending using splines. A sequential solution is created, which contains a model for the crustal field created by the equivalent sources, a single-line linear detrending or a multiple-line detrending of the model field and an equivalent source model that creates a crustal field model from the model of the data. The sequential solution is long and contains many calculations. Therefore a model that combines the equivalent sources model and the single-line linear detrending or multiple-line detrending model is created. The combined model is called a coestimation of the problem.

On the sequential parameter estimation and on the coestimated weighted Tikhonov regularization is used.

 The parameter estimation of the coestimation is also done when using maximum entropy on the equivalent sources and Tikhonov regularization on the single-line linear detrending.