Rebecca Humble

During this Physics Undergraduate Research Project, I underwent an investigation into the South Atlantic Magnetic Anomaly, SAMA, an area off the coast of South America with an abundance of highly energetic particles in the ionosphere, the highest point of the Earth’s atmosphere.
This region is the cause of the differing positions of the Earth’s axis in which our planet spins and it’s magnetic pole. The magnetic north pole is where a compass will point to, and the magnetic field that is created by the earth core causes radiation belts that surround the Earth. The geographic north pole is slightly off-set, about 11.5 degrees in fact. As a result, one of the radiation belts located at the South Atlantic comes closest to Earth’s atmosphere.
Now these radiation belts are extremely helpful to life on earth, they reflect and trap highly energetic particles that come from outer space that would otherwise do harm to biological life. However, where the radiation belt touches our ionosphere, it causes these energetic particles to be absorbed, unable to escape the atmosphere.
This region affects objects that orbit the earth, such as satellites and the International Space Station, therefore creating a need for a protective measures like shielding, switching the equipment going through the region or simply avoiding the area all together. On Earth's surface, there can also be disturbances to communications and GPS, causing no-fly zones, as well as inducing currents in transmission lines on the ground.
The aim of this study was to determine the size and variation of the anomaly. This was done by using satellite data from the French satellite DEMETER mission in order to produce maps of particle precipitation, peak intensity of energetic particles, at different orbital periods. This information included 3 important factors. The first of which was orbital parameters, the longitude and latitude, so that the data could be plotting over a world map. Second was the orbital time given in Julian date, this is the number of days since January 4713 BC, therefore needed to be converted into modern calendar days. Thirdly, the flux of energetic particles given at over 120 wavelengths.
The method of which involved programming and analysing data in MATLAB, a platform specifically designed for engineers and scientists. With no prior coding experience I found this programming language extremely helpful in visualising the data, all of which spans over a 5 year period, the length of the DEMETER mission.
The results of the coded model that was produced showed plotted intensities of the particles over a global map, along with a colour scale that when different times of the year were compared, differences could be easily seen. These plots were then compared with other data, such as solar activity and space weather events, to investigate any correlation between the anomaly, and find causes to its change in size and intensity. The results suggested geomagnetic storms caused multiple intense regions that spread over a wider area. This was done by using the disturbance storm time index, Dst, which measures geomagnetic activity and is used to assess the severity of magnetic storms. This was provided by Kyoto University in Japan, and suggested that when there was a geomagnetic storm, the anomaly split off particularly into two peak regions.
The ultimate conclusion of the project was further investigation is needed to understand the SAMA’s behaviour over a longer timeframe. Currently the centre of the anomaly is situated in the Atlantic Ocean, therefore there is a need for future research to predict its movement with the intent of preventing future effects on land if it moves further East/West or grows over a larger area.