# Polar Cap Patches Scaling Properties: Insights from Swarm Data
## 4 Discussion and Conclusions
Let us start by analyzing the spatial distributions of the values of the two scale exponents during geomagnetic quiet periods in both hemispheres, referring to the maps shown in the top panels of Figures 7 and 9. What immediately becomes clear is how the scale properties of electron density fluctuations present on the dayside tend to have values of both scale exponents higher than those of other regions. Considering the spatial location, it is immediately clear that this region identifies the cusp. The cusp is a region that extends for a few hours of MLT and whose position is a function of the \(y\) and \(z\) components of the interplanetary magnetic field. It is characterized by the continuousprecipitation of ions and electrons of external origin and it is therefore one of the regions most directly dependent on changes in solar wind conditions. The continuous precipitation of particles gives rise to a series of localized and transient structures, some of which may be triggered by changes in the orientation of the interplanetary magnetic field. The electron density measurements collected by the Swarm A satellite seem to indicate the presence of PCPs in this region, although not in large quantities (see Figure 5). This confirms previous studies [52], which noted that patches can be associated with weak soft electron precipitation. This suggests that PCPs are associated with flux tubes formed by open field lines, and therefore should exhibit different properties from those of the surrounding plasma that is not directly connected to the solar wind. The scaling features of these plasma density irregularities are also consistent with the analysis presented by [PERSON] et al. [53], who studied electron density data from the ICI-2 (Investigation of Cusp Irregularities-2) sounding rocket experiment in the high-latitude F region. They found that plasma enhancements subjected to soft particle precipitation displayed stronger random features with uncorrelated phases of density fluctuations, indicating that particle precipitation played a critical role in structuring the ionospheric plasma and creating turbulent-like structures. The only other region where similar properties to those found in the cusp can be observed, albeit less clearly, is around midnight at a magnetic latitude near 75\({}^{\circ}\). If we now focus on what happens during periods of high geomagnetic activity (bottom panels of Figures 7 and 9), we observe that the highest values of the second-order scaling exponent are found not only in the cusp region, but in this case, they involve the entire polar cap reaching the nighttime sector. Considering the structure of high-latitude convection cells and the motion of the plasma associated with them, it becomes clear that the regions characterized by higher values of the second-order scale exponent correspond to the area in between the two convection cells, generally characterized by an antisunward flow. When different layers of plasma move at different speeds or in different directions, shear layers can be created where the plasma flows are unstable and generate turbulence. This type of turbulence is the so-called shear-flow turbulence. On the other hand, where the plasma density changes rapidly over a short distance, the ions and electrons in the plasma experience different drift velocities due to the gradient and this creates a current that can generate electromagnetic waves and, under certain conditions, can become unstable and generate turbulence. Thus, both velocity shear and plasma density gradients are types of instabilities that can lead to the formation of plasma irregularities in the ionosphere, and in particular at high-latitudes. All of the regions with higher values of the second-order scaling exponent also have higher values of the first-order scaling exponent, indicating that the plasma density fluctuations have a more persistent character. This feature is shared by both hemispheres, though it is more visible in the Southern hemisphere.