Long‐lasting daytime equatorial plasma bubbles observed by the C/NOFS satellite

Abstract

[1] We report the first observations of long-lasting daytime equatorial plasma bubbles with the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. The most unusual features of the plasma bubbles are the persistence from the post-midnight sector through the afternoon sector and the extremely long lifetime of 12 h. In one case, the plasma bubbles were generated at 02:00-03:00 LT near the end of the main phase of a moderate magnetic storm and detected by C/NOFS over eight successive orbits, and the decrease of the ion density inside the bubbles was still as large as~30% at 14:00-15:00 LT. In another case, one group of plasma bubbles was generated near the sunset terminator and existed over the entire nighttime until the post-sunrise sector (06:00-08:00 LT), and another group of plasma bubbles was first detected at 04:00-06:00 LT and lasted until 11:00 LT. The latter group of bubbles occurred following a sharp northward turning of the interplanetary magnetic field (IMF) near the end of the main phase of a weak magnetic storm, and the overshielding electric field caused by the IMF northward turning and the storm time disturbance dynamo might both have contributed to the generation of the bubbles. The plasma bubbles reached 800 km or higher in altitude during daytime. The high altitudes may be critical for the long lifetime of the bubbles: the photo-ionization rate decreases rapidly with altitude. The photo-ionization process may take a long time to produce enough new plasma particles to fill the daytime bubbles at high altitudes.

The postsunset vertical plasma drift and its effects on the generation of equatorial plasma bubbles observed by the C/NOFS satellite

“…As reported by Huang et al . [, ], the plasma bubbles detected by C/NOFS during one orbit may have moved to a later local time, ~2 h later, during the next orbit due to the corotation and the zonal drift. The plasma bubbles between 19:00 and 21:00 LT are most likely related to the PRE at 18:00–19:00 LT during the same orbit.…”

Ionosonde observations of daytime spread F at low latitudes

“…Huang et al [2013] suggested that the zonal electric field associated with the disturbance dynamo or the overshielding electric field during magnetic storms was the possible driver. Huang et al [2013] suggested that the zonal electric field associated with the disturbance dynamo or the overshielding electric field during magnetic storms was the possible driver.…”

“…Huang et al [2013] suggested that the zonal electric field associated with the disturbance dynamo or the overshielding electric field during magnetic storms was the possible driver. But Huang et al [2013] proposed that the high altitudes of plasma bubbles were the key factor for the long lifetime of the irregularities because the photoionization rate decreases rapidly with altitude, which could take a long time to fill the daytime bubbles. But Huang et al [2013] proposed that the high altitudes of plasma bubbles were the key factor for the long lifetime of the irregularities because the photoionization rate decreases rapidly with altitude, which could take a long time to fill the daytime bubbles.…”

“…Li et al [2012] reported midlatitude ionospheric irregularities persisting into morning time during a magnetic storm and attributed to an eastward electric field associated with the disturbance dynamo. Huang et al [2013] reported two cases of the daytime plasma bubbles observed by the C/NOFS satellite during geomagnetic storms. Huang et al [2013] reported two cases of the daytime plasma bubbles observed by the C/NOFS satellite during geomagnetic storms.…”

“…Xiao et al [2012] recorded daytime ionospheric irregularities by HF Doppler and suggested that typhoon played a significant role. Huang et al [2013] considered that the eastward electric field with disturbance dynamo or the overshielding electric field generated the plasma bubbles. Huang et al [2013] considered that the eastward electric field with disturbance dynamo or the overshielding electric field generated the plasma bubbles.…”