Implication of tidal forcing effects on the zonal variation of solstice equatorial plasma bubbles

Equatorial plasma bubbles (EPBs) are elongated plasma depletions that can occur in the nighttime ionospheric F region, causing scintillation in satellite navigation and communications signals. EPBs are believed to be Rayleigh-Taylor instabilities seeded by vertically propagating gravity waves. A necessary pre-condition for EPB formation is a threshold vertical ion drift from the E region, which is required to produce the vertical plasma gradients conducive to this instability. Factors affecting the variation of EPBs therefore include magnetic declination, the strength of the equatorial electojet, and the wind dynamo in the lower thermosphere controlling vertical plasma drifts. In most longitude zones, this results in elevated EPB occurrence rates during the equinoxes. The notable exception is over the central Pacific and African sectors, where EPB activity maximizes during solstice. \citet{tsunoda_jgr2015} hypothesized that the solstice maxima in these two sectors could be driven by a zonal wavenumber 2 a...