Abstract
We studied the space weather effects on the South Atlantic Anomaly (SAA) magnetic response using Tsyganenko models. For the physical parameters characterizing the SAA, the study considered the minimum magnetic field, the location (longitude and latitude) of the SAA center, and the area of the SAA. Regarding the space weather parameters, we considered the solar wind dynamic pressure, the interplanetary magnetic field components, B_{yIMF} and B_{zIMF}, the Dst index, and the geodipole tilting angle. To study the magnetic field response of the SAA, several different versions of the Tsyganenko models, namely, T96, T01, and TS05, were used to describe the external magnetic field contributions. The main internal magnetic field was calculated by the International Geomagnetic Reference Field (IGRF-12). The magnetic field study of the SAA was realized in long- and short-term (seasonal and diurnal) variations. We found that the Dst index and the geodipole tilting angle were the strongest influencing parameters on the SAA magnetic field response at all altitudes. Moreover, it was revealed that both magnetic poles might be a possible cause of the SAA magnetic field response, resulting from the space weather conditions. Furthermore, the magnetic field behavior of the SAA was affected by hourly variations, where the largest changes occurred at dayside.
Highlights
The Earth’s lowest magnetic field intensity is expanding from Africa, through South Atlantic Ocean to South America, the so-called South Atlantic Anomaly (SAA)
We extend the investigation of space weather influence on the SAA magnetic field response, by studying its correspondence with altitude and by introducing the following variables: (1) the area of the SAA calculated beyond a selected threshold of the magnetic field strength; (2) the minimum magnetic field at the center of the SAA ( Bmin ); and (3) the location of the SAA defined as a point where the magnetic field is minimized
The study placed a typical spacecraft at Low Earth Orbit (LEO) that traveled across the SAA anomaly; a dangerous situation arose when the spacecraft body itself entered the high charging (= radiation) zone, whereas the safer region was outside of the SAA
Summary
The Earth’s lowest magnetic field intensity is expanding from Africa, through South Atlantic Ocean to South America, the so-called South Atlantic Anomaly (SAA). This phenomenon is interpreted as the presence of negative geomagnetic fluxes at the core– mantle boundary under the Earth’s surface, which in turn decreases locally the field strength. Such an interpretation is discussed in detail by Terra-Nova et al (2017), Tarduno et al (2015), Cottaar and Lekic (2016) and Aubert (2015). The effect of the Dst index on the short-term response of the SAA proton maximum
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