Impact of ICME- and SIR/CIR-Driven Geomagnetic Storms on the Ionosphere over Hungary

Abstract

We investigate the differences between the effects of geomagnetic storms due to Interplanetary Coronal Mass Ejections (ICME) and due to Stream Interaction Regions or Corotating Interaction Regions (SIR/CIR) on the ionospheric F2-layer during the maximum of solar cycle 24. We have created a unique list of the ICME- and SIR/CIR-driven geomagnetic storm events for the time interval between November 2012 and October 2014. Finally, 42 clear ICME and 34 clear SIR/CIR events were selected for this analysis. The individual geomagnetic storm periods were grouped by seasons, time of day, and local time of Dstmin and were analyzed using three different methods: linear correlation analysis using 4-hour averages of foF2 parameters and the geomagnetic indices (1st), daily variation of deltafoF2 (2nd), and 3D plotting: geomagnetic indices vs. time vs. deltafoF2 (3rd). The main phase day of the ICME- and SIR/CIR-induced geomagnetic storms was our main focus. We used manually evaluated ionospheric foF2 parameters measured at the Sopron ionosonde station and the geomagnetic indices (Kp, Dst, and AE) for this analysis. We have found that in most cases, the variation of the Dst index is the best indicator of the impact caused in the F2 layer. We conclude as well that the representation of the data by the third method gives a better description of the ICME and SIR/CIR-triggered storm behavior. In addition, our investigation shows that the SIR/CIR-related perturbations can be predicted with greater accuracy with the second method.

Ionosonde Measurements Comparison during an ICME- and a SIR/CIR-Driven Geomagnetic Storm over Europe

“…For this we calculated deltafoF2 and deltahF2, in percentage according to Equation 1, which display the deviations from the quiet day reference values. When the value in Figure 6 is 0%, the storm time value is equal to the median quiet day value at the respective half hour [34,47]. In Figure 5 the calculated deltafoF2 and deltahF2 values are displayed for (a) the ICME-and (b) SIR/CIR-driven events.…”