Contribution to the Research of the Effects of Etna Volcano Activity on the Features of the Ionospheric Total Electron Content Behaviour

Abstract

This research represents a contribution to the theory on the coupling of the volcanic activity and the ionospheric dynamics, represented by total electron content (TEC) patterns and their behaviour. The ionospheric response to the activity of the Etna volcano has been analysed using global navigation satellite system (GNSS)-derived TEC values, employing data from International GNSS Service (IGS) reference station near the volcano and on two distant IGS locations. Volcanic activity has been modelled using volcanic radiative power (VRP) data obtained by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system. The estimated minimal night TEC values have been averaged over defined index days of the VRP increase. During the analysed period of 19 years, the volcano activity was categorised according to pre-defined criteria. The influence of current space weather and short-term solar activity on TEC near the volcano was systematically minimised. The results showed mean/median TEC increases of approximately +3 standard deviations from the overall mean values, with peak values placed approximately 5 days before the VRP increase and followed by general TEC depletion around the time of the actual volcanic activity increase. Additionally, TEC oscillation pattern was found over the volcano site with a half-period of 6.25 days. The main interpretation of results indicates that the volcanic activity has modified the ionospheric dynamics within the nearby ionospheric region before the actual VRP increase, and that the residual impact in the volcano’s surrounding area refers to terrestrial endogenous processes and air–earth currents. Those changes can be detected during criteria predefined in the research: during quiet space weather conditions, observing night-time TEC values and within the limits of low short-term solar influence.

Anomalous Variations in Ionosphere TEC Before the Earthquakes of 2021 in the Different Parts of the Globe

“…Because of a more significant concentration of electrons, the ionosphere is a worldwide electric current, which is TEC (Total Electron Content, density of electrons in ionosphere). Many natural events, such as dust storms, thunderstorms [5], earthquakes, volcanic activity [6], radioactive gases [7], and solar radiation [8], induce variations in density of TEC. TEC rose during the previous high solar radiation cycle, which occurred in 2014 -2015; during this time, high-energy solar particles made contact with the earth's ionosphere, causing TEC to shift.…”

An Investigation on the Ionospheric Response to the Volcanic Explosion at Hunga Ha'apai in 2021

“…As for the specific direction of volcano‐ionosphere coupling research, it has been established that there is a correlation between ionospheric and volcanic activity, with TEC variation as an effective diagnostic parameter (Aoyama et al., 2016; Cahyadi et al., 2021, 2020; Heki & Fujimoto, 2022; Li et al., 2016; J.‐W. Lin, 2017; X. Liu et al., 2017; Maletckii & Astafyeva, 2022; Manta et al., 2021; Pandara et al., 2021; Saito, 2022; Shults et al., 2016; I. Toman et al., 2021; Verhulst et al., 2022; S.‐R. Zhang et al., 2022).…”

“…Based on the study of anomalous propagation characteristics in the ionosphere, a variety of information can be obtained, including the location of volcanic source, the scale of volcanic eruption, the height of plume, the rate of material ejection and the quality of ejection materials (Cahyadi et al., 2020; Li et al., 2016; Maletckii & Astafyeva, 2022; Shults et al., 2016; Watson et al., 2022). In the study of volcanic eruption activity cycles, it has been found that ionospheric anomalies can occur several days before the main eruption event (Li et al., 2016; Pandara et al., 2021; I. Toman et al., 2021). Particularly, the enhancement of TEC has been observed to occur during the main phase of volcanic eruption (I. Toman et al., 2021).…”

“…In the study of volcanic eruption activity cycles, it has been found that ionospheric anomalies can occur several days before the main eruption event (Li et al., 2016; Pandara et al., 2021; I. Toman et al., 2021). Particularly, the enhancement of TEC has been observed to occur during the main phase of volcanic eruption (I. Toman et al., 2021).…”

“…Liu et al, 2017;Nakashima et al, 2016). In addition, the intensity of ionospheric anomalies has also been confirmed to be significantly correlated with volcanic eruption intensity and plume height (Cahyadi et al, 2020;Manta et al, 2021;Shults et al, 2016;I. Toman et al, 2021).…”