The bow shock current is hypothesized to connect to the Earth's magnetosphere on open field lines and to contribute as a field aligned current to the polar ionospheric currents. In order to investigate this, two years of AMPERE data are used to compute the average region 1 currents, and average currents within the polar cap boundary, under different interplanetary magnetic field (IMF) clock angles and IMF magnitudes. The average currents are studied for stable IMF conditions. Therefore data is selected if the IMF By and Bz components do not change sign in a 30 minutes time interval to ensure sufficiently stable conditions. In addition, the AMPERE current maps are renormalized and recentered such that the region 1 currents have a fixed extent. These averaged current maps are then used to discuss the sources of the currents in the polar cap and their possible connection to the bow shock current. The currents in the polar ionosphere are found to generally agree with the statistical convection pattern. For a strong east-west IMF there are some discrepancies for the region 0 currents which indicates a possible bow shock current closure. Furthermore there are currents in the polar cap of the northern hemisphere for a strong southward IMF, which however do not have the expected polarity for bow shock current closure. Therefore they must have another, but unknown, origin. In addition, SuperDARN data is used to confirm that currents on the dayside of the polar cap and polwards of the Region 1 currents are on open field lines for a strong eastward or westward IMF. Further investigations are needed to confirm the bow shock closure in the ionosphere. Additional investigations are needed to identify the source of the polar cap currents for a strong southward IMF.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-184853 |
| Date | January 2021 |
| Creators | Krämer, Eva |
| Publisher | Umeå universitet, Institutionen för fysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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