Abstract
Using a whole atmosphere–ionosphere coupled model GAIA (ground-to-topside model of atmosphere and ionosphere), we have investigated which parameters mainly control day-to-day variation of vertical plasma drift at the evening terminator over magnetic equator, so-called pre-reversal enhancement (PRE). Day-to-day variations of the peak PRE are compared with those of electron density, eastward current density and eastward neutral wind in the E- and F-region over Chumphon (10.7° N, 99.4° E; 0.86° N magnetic latitude), Thailand during equinoctial months in 2011–2013. Eastward neutral wind in the F-region shows positive correlation with peak PRE, indicating that the F-region winds control the peak PRE through the mechanisms of the F-region dynamo (including E- and F-region coupling processes). Daytime eastward electric current at an altitude of 110 km, corresponding to equatorial electro jet (EEJ), is also positively correlated with the peak PRE. Correlation between the EEJ and PRE is the largest at 1700 LT, approximately 1.5 h prior to the peak PRE.
Highlights
Equatorial plasma bubble (EPB) is characterized by localized plasma density depletion in the ionosphere, and are well-known due to their unique nature and adverse effects on communication and navigation systems
The electron density in the E-region is quite smaller than in the F-region because the E-region plasma disappears due to rapid recombination soon after the solar extreme ultraviolet (EUV) radiation ceases
From comparison with the peak pre-reversal enhancement (PRE), it is found that the F 2 peak and bottomside altitudes ascend and the electron density at the F 2 peak altitude decreases when the peak PRE is intense (Fig. 2a, b)
Summary
Equatorial plasma bubble (EPB) is characterized by localized plasma density depletion in the ionosphere, and are well-known due to their unique nature and adverse effects on communication and navigation systems. Pre-reversal enhancement (PRE) is an enhancement of the vertical E × B drift due to the eastward electric field at the evening terminator at the magnetic equator. There have been many studies in the past to show the connection of the PRE on the generation of EPB using ground-based and satellite observations (Abadi et al.2015; Dabas et al 2003; Huang and Hairston 2015; Tulasi Ram et al 2006). Mechanisms controlling dayto-day variation of the EPB occurrence are still unknown it is important for the ionospheric community. Previous studies revealed that the daytime E × B drift and Equatorial Electro Jet (EEJ) have good positive correlation with the EPB generation (Dabas et al 2003; Tulasi Ram et al 2006)
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