A THEORETICAL LOW LATITUDE IONOSPHRIC MODEL

A theoretical low-latitud ionospheric model is presented. The continuity andmomentum equations of O⁺, H⁺ are solved, using operator splitting difference schemeon the fixed grid points distributed along the magnehc fields. Molecular ion densitiesof N₂⁺, O₂⁺, NO⁺ are calculated under the assumption of photochemical equilibrium.The modeling results fairly reproduced the gross features of daily development ofequatorial anomaly observed in East Asia under equinochal, solar maximum conditions.It is also shown that HWM90 model estimates much too large nighttime windvelocities at low latituds in East Asia, and the vertical drift velocity in East Asiamay be smaller than that in American region.