Analysis of the dynamics of ionospheric parameters during periods of strong geomagnetic storms and earthquakes in Kamchatka in 2023-2024 (based on GNSS data)
ISARD-2025-upper002
The total electron content (TEC) obtained from global navigation satellite systems (GNSS) data is widely used in the field of fundamental research in solar-terrestrial physics and applied problems of space weather. In order to study the variability of the ionosphere in Kamchatka Krai during periods of high geomagnetic activity, as well as during periods accompanied by high seismic and volcanic activities, an analysis of data from a regional network of GNSS receivers for March-April 2023 and August 2024 was carried out. For six receivers included in the regional network, the values of absolute vertical TEC were calculated taking into account differential code delays, and deviations of TEC values from the background level were determined. Also, based on the receiver network data, the disturbance index of the vertical variations of the total electron content (WTEC) was calculated for the periods of TEC oscillations in the ranges of 1-10 and 1-40 minutes, corresponding to medium- and large-scale ionospheric disturbances. For a detailed study of the dynamics of the estimated characteristics of the ionosphere state, an adaptive wavelet filtering algorithm based on a combination of discrete wavelet decompositions with adaptive threshold estimates was used.
As a result of the study, the behavioral features of the considered ionospheric characteristics observed during the periods of strong geomagnetic storms on March 23, 2023-March 24, 2023 (Kp=8, Dstmin=−163 nT), April 23, 2023-April 24, 2023 (Kp=8+, Dstmin =−213 nT), August 4, 2024 (Kp=7, Dstmin =−100 nT) and August 12, 2024 (Kp=8, Dstmin=−188 nT) were identified. The identified anomalous changes in the variations of absolute vertical TEC values had the form of negative deviations from the background level values, while an increase in the WTEC index values was observed for the considered periods of TEC oscillations. Approximately two days before the earthquake with a magnitude of M = 6.6, which occurred on 03.04.2023 02:06:56 (UT) off the east coast of Kamchatka, against the background of moderate geomagnetic activity, an increase in the WTEC indices to values of 0.1-0.3 TECU was observed at night local time for TEC oscillation periods in the range of 1-10 minutes for all considered GNSS receivers. During the eruption of the Shiveluch volcano, according to the klu1 receiver located in the vicinity of the volcano, against the background of low geomagnetic activity during 11.04.2023-12.04.2023 at night LT, TEC disturbances were observed that exceeded the upper limit of the background value range. The remaining receivers noted an increase in the WTEC indices to values of 0.08-0.15 TECU for TEC oscillation periods in the range of 1-10 minutes. During the day preceding the earthquake with a magnitude of M=7.0, which occurred off the east coast of Kamchatka on 17.08.2024 19:10:25 (UT), against the background of moderate geomagnetic activity (Kp=3−), TEC variations were observed, the positive relative deviations of which from the background level reached values from 20% to 40%. A detailed analysis of variations in the estimated characteristics of the ionosphere state, performed using wavelet decompositions, confirmed the reliability of the obtained research results.
The work was supported by IKIR FEB RAS State Task (subject registration No. 124012300245-2).