A Modeling Study of the Influence of Electric Fields on Ionosphere Semiannual Variations at Mid- and Low Latitudes

Abstract

With a theoretic ionospheric model, we investigate the semiannual variations of the ionospheric F2 region peak electron density (NmF2) at mid- and low latitudes under the low solar activity and quiet geomagnetic conditions, and focus on how the electric fields modify the semiannual component of NmF2. The result indicates that when the input electric fields have no semiannual variation, the NmF2 at the geomagnetic equator also has some semiannual component, and the amplitudes of semiannual component decrease as the latitude increases. When the input electric fields have some semiannual component, the amplitudes of NmF2 semiannual component is strongly modified, and seems to be dependent upon magnetic latitudes. It is also found the modification of electric fields on the NmF2 may have a close relationship with the ‘fountain effect’ in the equatorial ionosphere.