16:45 〜 17:00
[PEM12-42] Do long-term changes modify the ionospheric response to geomagnetic activity?
キーワード：Long-term changes, NmF2, F2 layer, geomagnetic activity, Juliusruh
Previous analyses have identified significant long-term variations in the ionosphere-thermosphere system. However, the physical mechanisms behind these observed ionospheric trends remain unclear. Model studies suggest that geomagnetic activities can influence CO2-driven trends in the F2 layer of the ionosphere, either strengthening or weakening these trends. This study aims to investigate how the ionosphere's NmF2 (the peak electron density) is affected by geomagnetic activity and to evaluate its stability across different solar cycles (SCs).
To account for variability in solar activity, a third-degree polynomial fit model is applied using F30, a proxy for solar extreme ultraviolet radiation. This model is executed separately for each solar cycle, season, and local time (LT) hour.
Hourly values of peak electron density (NmF2) from Juliusruh station (54.6° N, 13.4° E) are analyzed from 1957 to 2023. The study examines the seasonal variability in the ionosphere's response to geomagnetic activity using various geomagnetic indices, including Kp, Ap, Am, Kpm, and Hp60. The results indicate higher correlation values (below 0.6) during the local summer months in the morning hours with the Kp index delayed by approximately 20 hours. Under these conditions, the analysis for Juliusruh reveals no significant changes in the ionosphere's response to geomagnetic activity throughout five solar cycles. Additionally, findings from Juliusruh are consistent with those from six other ionospheric stations located at similar geomagnetic latitudes in both hemispheres, which also do not demonstrate any variation over time
To account for variability in solar activity, a third-degree polynomial fit model is applied using F30, a proxy for solar extreme ultraviolet radiation. This model is executed separately for each solar cycle, season, and local time (LT) hour.
Hourly values of peak electron density (NmF2) from Juliusruh station (54.6° N, 13.4° E) are analyzed from 1957 to 2023. The study examines the seasonal variability in the ionosphere's response to geomagnetic activity using various geomagnetic indices, including Kp, Ap, Am, Kpm, and Hp60. The results indicate higher correlation values (below 0.6) during the local summer months in the morning hours with the Kp index delayed by approximately 20 hours. Under these conditions, the analysis for Juliusruh reveals no significant changes in the ionosphere's response to geomagnetic activity throughout five solar cycles. Additionally, findings from Juliusruh are consistent with those from six other ionospheric stations located at similar geomagnetic latitudes in both hemispheres, which also do not demonstrate any variation over time