The Effect Of Midnight Temperature Maximum Winds On Post-Midnight Equatorial Spread F

The SAMI3/equatorial spread F (Sami3 is also a model of the ionosphere/ESF) code is used to simulate the growth of equatorial plasma bubbles in the presence of a background wind field based on measured winds. The measured winds exhibit the well-known "midnight temperature maximum" (MTM) pattern, in which an equatorward wind occurs simultaneously with a cessation in the zonal wind. The MTM is often preceded by strong equatorward winds (about 100 m/s). The circumstance where the MTM winds are symmetric across the equator is considered; here the meridional wind component in the southern hemisphere is the reverse of the northern meridional wind. The timing of the wind pattern relative to the imposition of a seed for the ESF instability is explored. We find that the simultaneous occurrence of a seed wave and a strong converging meridional wind pattern can produce post-midnight ESF. We further find that the seed wave and the sudden cessation of the zonal winds can also produce post-midnight ESF. The Magnetic mEridional NeuTrAl Thermospheric code verifies the occurrence of converging meridional wind patterns such as those simulated here, based on ionosonde data. Results suggest that regional-scale wind measurements would aid in the prediction signal-disrupting ionospheric bubbles.