Relationship of the Pre-Reversal Enhancement (PRE) and the Bottomside Ionospheric Structure to Equatorial Plasma Bubble (EPB) Formation

Equatorial plasma bubbles (EPBs) are ionospheric irregularities that cause radiowave scintillation, which poses problems in satellite communications and navigation. We report the examination of the ionospheric conditions that precede their formation. Two phenomena related to EPB formation are the pre-reversal enhancement (PRE), an enhancement of the vertical E × B drift due to the eastward electric field at the evening terminator at the magnetic equator, and the structure of the bottomside ionosphere. Three databases were generated from satellite measurements of the equatorial ionosphere. The first is a database of identified EPB occurrences and the associated ionospheric characteristics from the in situ ion velocity meter (IVM) instruments aboard the Communication/Navigation Outage Forecasting System (C/NOFS) and the Ionospheric Connections Explorer (ICON) satellites. The second database consists of the characteristics of the vertical drifts at 18-19 magnetic local time, to identify instances of PRE using in situ data from the C/NOFS and ICON IVM instruments. The third database contains information on the altitude profiles of ionospheric density, in particular the structure of the bottomside ionosphere, observed by the Far-Ultraviolet (FUV) imager aboard ICON. We examine the relationship of EPB occurrence with the strength of the PRE and the structure of the bottom-side F layer.