In this study, we documented the midlatitude F2-layer response to five strong geomagnetic storms with minimum Dst < –150 nT that occurred in solar minimum years using hourly values of the F2-layer critical frequency (foF2) from four ionosondes located in different hemispheres. The results were very limited, but they illustrated some peculiarities in the behavior of the F2-layer storm. During equinox, the characteristic ionospheric disturbance patterns over the Japanese station Wakkanai in the Northern Hemisphere and the Australian station Mundaring in the Southern Hemisphere were consistent with the well-known scenario by Prölss (1993); however, during a December solstice magnetic storm, both stations did not observe any noticeable positive ionospheric disturbances. Over the “near-pole” European ionosonde, clear positive ionospheric storms were not observed during the events, but the “far-from-pole” Southern Hemisphere station Port Stanley showed prominent enhancements in F2-layer peak electron density in all magnetic storms except one. No event produced noticeable nighttime enhancements in foF2 over all four ionosondes.

1. INTRODUCTION
 2. DATA
 3. RESULTS
 4. CONCLUSION AND DISCUSSION
 ACKNOWLEDGMENTS
 REFERENCES

• Vitaly P. Kim(Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation, Russian Academy of Sciences, Moscow 142190, Russia)
• Valery V. Hegai(Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation, Russian Academy of Sciences, Moscow 142190, Russia) Corresponding Author