Journal Highlights

The appearance of plasma bubbles at mid latitudes during severe storms

Editor’s Highlight—

 

Based on data analysis of Total Electron Content estimated from Global Navigation Satellites and Defense Meteorological Satellite Program spacecraft ion density measurements, this paper reports the occurrence of plasma bubbles (depletions) in an anomalously high middle-latitude region (41 degrees) over the European sector during two intense geomagnetic storms in 2000 and 2001. Thus, conditions conducive to upward plasma drift close to the equator can extend to the mid-latitude ionosphere making the mid-latitude regions susceptible to the eastward penetration electric field during intense geomagnetic storms. The authors estimate a maximum apex height of the post sunset plasma depletions as about 4000 km. The data show that the evening middle-latitude plasma was enhanced and that the Equatorial Ionization Anomaly extended to the middle-latitude European region during the time of the plasma bubble occurrence. The authors propose an eastward penetration electric field associated with the Bz southward turning as a possible mechanism for the enhancement of the middle-latitude plasma and subsequent middle-latitude plasma bubbles. Although the mid-latitude ionosphere is generally considered safe from radio signal scintillations effects, this study shows that there may be no safe zone during intense storms.