Characteristics of Ionospheric Irregularities Using GNSS Scintillation Indices Measured at Jang Bogo Station, Antarctica (74.62°S, 164.22°E)

Abstract

Global Navigation Satellite System (GNSS) signals strongly depend on the ionospheric conditions, which are composed of electrons and ions generated by solar radiation and particle precipitation. Ionospheric plasma irregularities may cause the scintillation of the GNSS signals or even the loss of signal lock, resulting in the reduction of positioning accuracy and timing precision. Phase scintillation phenomenon is known to occur frequently at high latitudes and primarily related to a significant plasma density gradient, which is due to fast plasma flows in the polar region, energetic particle precipitation in the auroral region, polar cap patches, or several instability mechanisms. Statistical studies are required to understand the characteristics of ionospheric (both phase and amplitude) scintillations at high latitudes. Here, we report the results of ionospheric scintillation measurements at Jang Bogo Station (JBS; 74.62°S, 164.22°E), located inside the polar cap region in Antarctica. The occurrence rates of ionospheric scintillations over the JBS are recorded for 2 years (2017-2018) during solar minimum conditions. The occurrence rates of amplitude scintillations increase only at lower elevation angles (below 30°), which are hard to determine whether the source is ionospheric irregularity or ambient noise such as multipath. In contrast, the occurrence rates of phase scintillations depend on the azimuth angle, season, magnetic activity, magnetic local time, and signal frequency. The results of our analysis suggest that users of the GNSS should consider these parameters to prepare for the degradation of the GNSS performance at high latitudes in the Southern Hemisphere.

Steepening Plasma Density Spectra in the Ionosphere: The Crucial Role Played by a Strong E‐Region

“…Conversely, free energy can push a blob of plasma toward instability without ever making it unstable, which would increase the decay time of stable plasma. As a direct consequence of electron precipitation, the auroral region shows an abundance of plasma irregularities (Kelley et al., 1982), which may be the cause of widespread GPS scintillations (Hong et al., 2020; Prikryl et al., 2015).…”

Measuring Small-scale Plasma Irregularities in the High-latitude E- and F-regions Simultaneously

“…The implication is that, given a conducting E-region, whenever a small-scale turbulent structure is observed in the F-region, it should also be observable in the E-region. Figure 2 clearly shows that this is true for scales as small as 1.5 km, fluctuation scales that are favourable for GNSS scintillations [ [49][50][51][52][53]. Our results then indicate that such radio scintillations could well originate in the E-region at high latitudes [ 54,55 ].…”

Inferring the Horizontal Speed of an Ionospheric Irregularity From a Single GPS Scintillation Receiver at High Latitudes

“…The probability densities of ionospheric irregularity horizontal speeds were calculated from the 5‐ min interval data. The occurrence rates of ionospheric scintillation are only a few percentages with respect to the total number of observations (Hong et al., 2020), and data selection was based on the phase scintillation index, so that the total number of inferred ionospheric irregularity speeds by GPS measurements was exceedingly smaller than those by radar measurements. In addition, because CASES at JBS received civilian signals that fewer satellites could transmit, the total number of inferred ionospheric irregularity speeds was less in the Southern Hemisphere than in the Northern Hemisphere.…”

“…Raw signal information, such as the carrier phase, in‐phase accumulation ( I ), and quadrature accumulation ( Q ), is recorded at a high temporal resolution of 100 Hz (Crowley et al., 2011; O’Hanlon et al., 2011). Jang Bogo Station is located in the polar cap region where the ionospheric and magnetospheric phenomena such as polar cap patches, field‐aligned currents, and inner auroral oval are highly active; therefore, ionospheric scintillations are frequently observed after applying a high‐pass filter with 0.1 Hz cutoff frequency (Hong et al., 2020). The Canadian High Arctic Ionospheric Network (CHAIN) is a deployed array of GPS receivers to understand the Sun‐Earth system in the Northern Hemisphere (Jayachandran et al., 2009).…”