Análise das componentes horizontal e vertical do campo geomagnético na região da anomalia magnética do atlântico sul

Abstract

The geomagnetic field is generated mainly within the Earth, having a predominantly dipolar geometry, where the total geomagnetic intensity (F) is the result of the contributions of its horizontal (H) and vertical (Z) components. Due to its dipolar configuration it is expected that the highest F values will be observed in the polar regions, and the lowest in the equatorial region, being the same behavior expected for Z and the opposite behavior for H, where it would present its highest values in the equatorial region and its lower values in the polar regions, giving the field a shield character against the entry of electrically charged particles (ECPs). However, previous studies have shown that the field does not behave this way, this is due to a magnetic anomaly present in the South Atlantic region, the South Atlantic Magnetic Anomaly (SAMA). This anomaly presents a non-dipolar configuration, acting in the field as an opening for the entrance of the ECPs, having strong characteristics as a westward drift, and increase of its coverage area. In order to analyze the importance of the non-dipolar portion for the geomagnetic components H and Z, by investigating the temporal variation of intensity of these components for the last 115 years. The results show the influence of the non-dipolar portion to the total field, showing decrease in horizontal intensity in areas close to the equator. Analysis of the contribution of components H and Z to F show us an increase of contribution of component Z, as well as a decrease of H for the region affected by SAMA.