Structure of the Earth's magnetosphere under Northward IMF conditions

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The Earth's magnetic field forms a cavity in the solar wind called the magnetosphere; the interaction between the solar wind and the magnetosphere is ultimately responsible for the dynamics of near-Earth space, including variations in the intensity of the radiation belts and the most spectacular displays of the aurora (the northern and southern lights). The nature of these interactions depends on the orientation of the magnetic field associated with the solar wind (the interplanetary magnetic field, or IMF); a "southward" orientation of the IMF (opposite to the Earth's magnetic field) is preferential for many magnetospheric processes, but the IMF direction is highly variable, and the dynamics of the magnetosphere under northward IMF conditions are, in comparison, poorly understood. One example of this is the structure of the night side of the Earth's magnetosphere, which forms an extended magnetotail. The magnetotail consists of a plasma sheet sandwiched between two low density regions called the lobes. In the textbook picture of the magnetotail, the low latitude "plasma sheet" is hot, whereas the plasma in the lobes is very cold and usually low in density. However, a recent series of papers have begun to challenge this paradigm, and have found that under certain conditions uncharacteristically hotter/higher density plasma can be observed in the lobes, some of which are associated with perplexing "high latitude" auroral emissions which lie poleward of the main auroral region. The mechanisms causing both the plasma structure and the high latitude auroral emissions are hotly debated. The aim of this project is to use in situ satellite data from spacecraft such as the European Space Agency's Cluster mission to determine and explain the structure of the magnetotail during the more complex intervals associated with northward IMF. This will begin with a statistical classification of the plasma environment during northward IMF conditions, and will lead on to a comparison with global scale auroral datasets. We expect this work will lead to a significant contribution to our understanding of the magnetosphere's response to northward IMF conditions.