Abstract
In this master thesis we will study a space weather phenomena known as polar cap patches (PCPs). Polar cap patches are patches of high density plasma drifting anti sunward across the polar cap. As a result of this anti-sunward drift, the patches have a leading and a trailing edge. We will investigate whether the gradient drift instability results in more complex plasma density structuring in the trailing edge of polar cap patches. This is done by the processing and analyzing of in situ measurements of the ionospheric plasma density made by the Swarm satellite constellation. The collected data span over a 5.5 year period, from July 2014 to the end of 2019. Subsequently, we compared the density structures in the trailing and leading edge of polar cap patches using the standard deviation of linear regressions with respect to the plasma density. Statistical analysis of the standard deviation ratios was done using a combination of histograms and bar charts. The results of this study suggest that there is in fact a substantial difference in density structuring in polar cap patch edges. The underlying hypothesis, stating that the gradient drift instability affects the trailing edge of polar cap patches, is therefore strengthened. Based on this, we will also investigate when we can expect signal degrading due to the formation of complex density structures in polar cap patches to be most prevailing. Therefore, we have conducted an interhemispheric polar cap patch occurrence rate study. The results of this study present that polar cap patches occur more frequently during local winter conditions, with respect to both hemispheres. Ultimately, suggesting that signal degrading is prominent during local winter conditions.