Quiet‐Time Equatorial Ionization Anomaly Reversal Observed by the Satellites of Defense Meteorological Satellite Program (DMSP) and Ionospheric Connection Explorer (ICON)

We investigated the quiet‐time temporal variations of the Equatorial Ionization Anomaly (EIA) and underlying plasma fountain observed in the topside ionosphere during the various F‐region equatorial E × B drift events recorded by the Jicamarca Incoherent Scatter Radar and simulated by SAMI3. Observations were made by Defense Meteorological Satellite Program (DMSP) at ∼840 km (altitude) and high sunspot numbers and by Ionospheric Connection Explorer (ICON) at ∼600 km and low sunspot numbers. Drift events included the F‐region equatorial upward E × B drift's (a) evening increase, (b) prereversal enhancement (PRE) and (c) reversal, and the subsequent (d) equatorial downward E × B drift's enhancement. Our findings reveal these (a‐d) drift events' characteristic signatures (1–6) observed by DMSP and ICON. These include (1) the asymmetric two‐peak EIA and underlying forward fountain before the PRE, (2) the well‐developed symmetric two‐peak EIA with plasma bubbles at crest‐latitudes and underlying strengthened forward fountain during the PRE, (3) the breaking‐down EIA with plasma bubbles at trough‐ and crest‐latitudes and underlying reversing forward fountain after the PRE, and (4) the equatorial ionization peak and underlying reverse fountain. Importantly, the PRE‐signatures observed also include (5) the additional plasma density peak developed upon the EIA crest due to the additional F 3 layer's formation (observed by ICON) and (6) the enhanced equatorial zonal eastward drift causing the equatorial ionosphere's super rotation (observed by DMSP). Finally, we conclude that the F‐region equatorial E × B drift variations drove the two‐peak EIA's and underlying plasma fountain's variations (a–d), of which characteristic signatures (1–6) were well observable in the topside ionosphere during the time periods investigated.