Regional Modelling of the Southern African Geomagnetic Field using Harmonic Splines

TL;DR

This paper develops a regional geomagnetic field model for southern Africa using harmonic splines, based on historical data, revealing rapid geomagnetic changes from 1961 to 2001.

Contribution

It introduces a novel harmonic spline-based regional modeling approach applied to southern Africa's geomagnetic data, improving understanding of rapid field variations.

Findings

Detailed regional geomagnetic field model from 1961 to 2001

Revealed rapid geomagnetic changes in southern Africa

Validated method on synthetic data

Abstract

Over the southern African region the geomagnetic field is weak and changes rapidly. For this area series of geomagnetic field measurements exist since the 1950s. We take advantage of the existing repeat station surveys and observatory annual means, and clean these data sets by eliminating jumps and minimising external field contributions in the original time series. This unique data set allows us to obtain a detailed view of the geomagnetic field behaviour in space and time by computing a regional model. For this, we use a system of representation similar to harmonic splines. Initially, the technique is systematically tested on synthetic data. After systematically testing the method on synthetic data, we derive a model for 1961 to 2001 that gives a detailed view of the fast changes of the geomagnetic field in this region.