MODELING STUDY OF NIGHT-TIMEENHANCEMENTS IN f₀F₂ AT LOW-LAfITUDES

The nighttime anomalous enhancements in f₀F₂ are simulated in this paperusing a 2D low-latitude ionospheric theoretical model. The number densities, velocities of ions and electrons are calculated in the model by solving the plasmatransport equations. Typical characteristics of pre-midnight and post-midnight increases appeared in the values of calculated f₀F₂ near the equatorial anomaly crestlatitudes. The larger the peak electron densities, the stronger the enhancement is,which is in consistent with observed results. It is shown that the transport of plasmainduced by E×B vertical drift and the field-aligned neutral winds is important inthe formation of nighttime increases in f₀F₂ at crest latitudes.