[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-01] On occurrence of ionospheric super plasma bubbles during severe geomagnetic storms

★Invited Papers

*Irina Zakharenkova^1,2、Iurii Cherniak^1,2、Andrzej Krankowski¹ (1.Space Radio-Diagnostic Research Center, University of Warmia and Mazury, Olsztyn, Poland、2.University Corporation for Atmospheric Research, Boulder CO, USA)

キーワード：ionospheric super plasma bubbles, geomagnetic storms, prompt penetration electric fields, scintillations

Equatorial plasma bubbles (EPBs) represent a typical post-sunset quiet-time phenomenon, when large-scale plasma density depletions form in the equatorial ionosphere and expand to high altitudes up to 1000 km. Depending on season, location, and solar activity level, the quiet-time EPBs occur primarily within 10°-15° S/N range of magnetic latitudes (MLAT). The EPB phenomenon poses one of the major space weather threats to space-based communication and navigation systems in geomagnetically quiet conditions. The formation of EPBs is strongly impacted by the intense electric fields during geomagnetic storms; these fields may suppress EPBs or significantly boost the EPB growth. The term “super plasma bubble” was first introduced by Ma & Maruyama (GRL, 2006) in one of the earliest reports of storm-time EPBs reaching unusually high latitudes (31° MLAT) in the Japanese sector during the February 2000 geomagnetic storm. Recent advancements in observational capabilities have resulted in an increased number of cases with EPB detections at midlatitudes during geomagnetic storms of different intensity - confirming that storm-induced super plasma bubbles can reach midlatitudes more often than previously thought. The main objective of this study is to better specify the rare occurrence of super plasma bubbles, detailing their spatio-temporal evolution, and better understanding pre-conditions for their development in the coupled ionosphere-magnetosphere system. Our comprehensive multi-instrument analysis combined ground-based and space observations from GNSS, ionosondes, and several satellite missions (COSMIC-2, GOLD, DMSP, Swarm). We have investigated the ionospheric response to severe geomagnetic storms occurred in the last ten years and have shown the formation of super plasma bubbles expanding from equatorial latitudes to middle latitudes in the European/African and American longitudinal sectors during the main phase of the storms. Intense ionospheric irregularities associated with post-sunset super-EPBs development were detected up to 30°-40° MLAT. Strong amplitude scintillations were registered by the ground-based GNSS and space-borne COSMIC-2 observations. Formation of super-EPBs was associated with storm-induced prompt penetration electric fields of eastward direction. We analyze the similarities and differences in super-EPBs’ occurrence, duration, and longitude range occupied by super-EPBs with respect to the variations in geomagnetic conditions like steady southward IMF Bz, phase of geomagnetic storm, background ionospheric conditions, dusk sector location, etc. We also discuss impact of storm-induced super plasma bubbles on performance degradation of the satellite-based augmentation systems like EGNOS in Europe and WAAS in the U.S.