Global Navigation Satellite Systems (GNSS) are subject to disturbances caused by plasma irregularities in the ionosphere. Studies have suggested that in addition to the gradient drift and Kelvin‐Helmholtz instabilities, electron precipitation may be important for phase scintillations in the dayside auroral region. This study combines in situ Swarm data with ground GNSS observations to investigate the potential role of filamentary field‐aligned currents (FACs) on phase scintillations in the dayside auroral region by analyzing 22 events with phase scintillations exceeding 0.45 radians. We observe colocation between regions of severe phase scintillations and highly filamented FACs with fluctuations measured in the spacecraft frame of the order of 20 Hz. The observations indicate that filamentary FACs are crucial drivers for irregularities responsible for creating severe phase scintillations measured in the dayside auroral region and are thus of significant importance in the context of space weather impact on satellite communication.

Plasma depletions in the disturbed equatorial ionosphere are known to be associated with magnetic fluctuations and Alfvén waves. Here, using data from the Swarm B satellite's vector field magnetometer and electric fields instrument at an altitude of ∼500 km, we present evidence of standing Alfvén modes trapped within strong density depletions. Fourier transforms of electric (δE) and magnetic (δB) perturbations reveal harmonic structure with anticorrelated peaks and relative phase shifts approaching ±90°, in agreement with a simple model of standing waves sampled from a moving spacecraft. The mode frequencies allow us to estimate the field‐aligned length of the bubbles, which we find to be in the range of 110–200 km. This value is much smaller than the overall field line length mapped to the two E‐region footprints, indicating that the waves we observe do not couple to the lower ionosphere.

In space plasma physics, ULF waves play a significant role, for example, in coupling the solar wind, magnetosphere, and ionosphere. They also serve as a valuable diagnostic of coupling processes in the magnetosphere-ionosphere system. "Geomagnetic pulsations" is a general term for ULF waves observed on the ground. Jacobs et al. (1964) divided geomagnetic pulsations with frequencies less than 5 Hz into five regular and two irregular frequency bands. Quasi-sinusoidal waves are referred to as pulsation continuous (Pc), while irregular waveforms are referred to as pulsation irregular (Pi) (Arora et al., 2011). The three lower frequency bands of Pc waves (Pc3-5) are relevant to magnetospheric field line and cavity resonances (the subject of this paper), whereas internal wave-particle interactions generate the higher-frequency bands (

<p>Ionospheric irregularities are structures or fluctuations of plasma density having different scale sizes. These irregularities can disrupt radio waves and produce errors in space-based or ground-based technologies, which depend on the GNSS/ GPS signals. Post-sunset ionospheric plasma irregularities are a common characteristic of the equatorial ionosphere. These irregularities, associated with plasma bubbles, are defined as strong density depletions relative to the background plasma as determined by in situ measurements. <br />Finding a system parameter's probability distribution function (PDF) can lead us to understand the system's underlying physics. In this study, we investigate the probability distribution of the integrated power of post-sunset plasma density irregularities in the equatorial ionosphere measured with the Langmuir probes on Swarm C in four different frequency bands between 0-1 Hz for the entire Swarm mission. We find evidence of  "heavy tail" distribution in the PDFs, indicating the system's complexity and self-organized criticality. Moreover, we study the relation between Integrated power and different geomagnetic indices, e.g. F10.7 and sunspot number, to find the potential drivers of severe events. While we find no obvious driver of individual events, we find a strong solar cycle dependence in their occurrence.</p>

<p>Ionospheric irregularities are fluctuations or structures of plasma density that affect the propagation of radio signals. Whenever large-scale irregularities break up into meso and small-scale irregularities, these processes become similar to a turbulence cascade. In order to have a better comparison between this and plasma density irregularities, we study different orders of structure functions of plasma density of total loss of lock events measured with the faceplate measurements of plasma density and the GPS measurements from the Swarm mission. Total loss of lock of GPS signal is a physical proxy for severe degradation of GPS signals. In addition to different orders of structure-function, we study the existence of self-similarity or multifractality of plasma density of total loss of lock events to investigate any possible intermittent fluctuations. </p>