Are plasma bubbles a prerequisite for the formation of broad plasma depletions in the equatorial F region?

• Published in: Geophysical research letters 2013-07, Vol.40 (14), p.3491-3495
• Main Authors: Kil, Hyosub, Lee, Woo Kyoung
• Format: Article
• Language: English
• Subjects: Backscattering; Bubbles; Depletion; Earth sciences; Earth, ocean, space; Echoes; equatorial ionosphere; Equatorial regions; Exact sciences and technology; F region; Irregularities; Plasma; Plasma bubbles
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/grl.50693

Formation of broad plasma depletions (BPDs) at night in the equatorial F region is understood in association with plasma bubbles. However, we report BPDs that do not show a connection with bubbles. The characteristics of BPDs are investigated using the observations of the Communication/Navigation Outage Forecasting System (C/NOFS) satellite on 31 December 2008, 28 July 2010, and 1 February 2011. On those days, BPDs are detected in the longitude regions where C/NOFS did not detect bubbles prior to the detection of BPDs. The coincident C/NOFS and radar observations over Jicamarca in Peru show the occurrence of BPDs at the time when backscatter echoes are absent and at the height below backscatter echoes. These observations indicate that bubbles are not a prerequisite for those BPDs. The detections of those BPDs can be explained by the uplift of the equatorial F region peak height above the satellite orbit. Key Points Equatorial broad plasma depletions develop in the absence of bubbles Broad plasma depletions occur when the ionosphere is lifted Broad plasma depletions are the signature of bottomside irregularities