# Polar Cap Patches Scaling Properties: Insights from Swarm Data
###### Abstract  
Among the effects of space weather, the degradation of air traffic communications and satellite-based navigation systems are the most notable. For this reason, it is of uttermost importance to understand the nature and origin of ionospheric irregularities that are at the base of the observed communication outages. Here we focus on polar cap patches (PCPs) that constitute a special class of ionospheric irregularities observed at very high latitudes in the F region. To this purpose we use the so-called PCP flag, a Swarm Level 2 product, that allows for identifying PCPs. We relate the presence of PCPs to the values of the first- and second-order scaling exponents and intermittency estimated from Swarm A electron density fluctuations and to the values of the Rate Of change of electron Density Index (RODI) for two different levels of geomagnetic activity, over a time span of approximately 3.5 years starting on 16 July 2014. Our findings show that values of RODI, first- and second-order scaling exponents and intermittency corresponding to measurements taken inside PCPs differ from those corresponding to measurements taken outside PCPs. Additionally, the values of the first- and second-order scaling exponents and of intermittency indicate that PCPs are in a turbulent state. Investigation of the coincidence of loss of lock (LoL) events with PCPs displayed that approximately 57.4% of LoLs in the Northern hemisphere and 45.7% in the Southern hemisphere occur in coincidence of PCPs when disturbed geomagnetic activity is considered. During quiet geomagnetic conditions these percentages decrease to 51.4% in the Northern hemisphere and to 20.1% in the Southern hemisphere. space weather; ionospheric irregularities; polar cap patches; turbulence; Swarm satellite; geomagnetic activity; loss of lock Article  
Polar Cap Patches Scaling Properties: Insights from Swarm Data  
Roberta Tozzi, Tozzi  
of as an island of plasma whose density is at least double than that of the surrounding background plasma and whose size is approximately in the range 100 \(\div\) 1000 km. A PCP usually enters the polar cap through the dayside then, driven by ionospheric convection, crosses the polar cap, to finally exiting the polar cap hours later, near midnight [5]. PCPs form from the high-density plasma reservoir found in the dayside ionosphere, where the low solar zenith angles and resulting high solar EUV ionization ensure a much higher plasma density than elsewhere. PCP formation is still a debated topic and different mechanisms have been proposed [6]. According to [PERSON] and [PERSON]. [7], for instance, these islands of high density plasma are produced by the bursty nature of dayside reconnection. When the Dungey cycle is ongoing [8], these are transported across the polar cap by ionospheric convection, which acts exactly like a conveyor belt. This means that plasma density irregularities can travel for hours and over long distances. Their names change depending on where they are observed. They are only referred to as PCPs if they occur within the polar cap; otherwise, they are referred to as auroral blobs [9]. Because different mechanisms may be in charge of their generation and development, it was decided to separate them by giving them different names. Due to their drifting nature, PCPs are susceptible to the gradient-drift instability (GDI) [1], which can break them down into smaller plasma structures with sizes as small as a few meters. These small ionospheric irregularities are capable of negatively affecting trans-ionospheric radio signals at commonly used frequencies [10]. Since the first PCP observations, several investigations have been conducted, both through case studies based on data from rockets or satellites (e.g., [11; 12; 13; 14] and references therein) and statistical analyses based on data from long-lived satellites such as CHAMP, Dynamics Explorer 2, and Swarm (e.g., [15; 16; 17]).