17:15 〜 19:15
[SEM16-P19] Eigen mode analysis of the geomagnetic main field: implication to the secular variation evolution
キーワード：geomagnetic secular variation, eigen mode analysis
The slow temporal variations in Earth’s magnetic field, namely the geomagnetic secular variation (SV), originate in the liquid outer core. The temporal and spatial characteristics of the geomagnetic SV provide vital information for the geomagnetic field evolution and the Earth’s core dynamics. We study the temporal and spatial characteristics by presenting the eigen mode analysis of the geomagnetic main field based on the COV-OBS.x2 model. We found that the geomagnetic SV has obviously regional characteristics. The Pacific region is a region with stable magnetic field structure and slow change, which can be basically represented by the first eigenmode. The northern, central and southern parts of the Atlantic Ocean belong to different eigenmodes and have different characteristics of secular variation. The Indian Ocean is a region with significant and complex changes, and almost every eigenmode has a certain contribution. The intensity of each eigen mode has its own unique period. The small-scale magnetic anomaly corresponds to the short period, while the large scale magnetic anomaly corresponds to the long period. The non-dipole fields are a synthesis of several eigenmodes.