电离层电场的半年变化对F2区峰值电子浓度的影响

利用一个电离层理论模式，模拟了太阳活动低年、地磁宁静情况下，中低纬和赤道地区电离层F2区峰值电子浓度(NmF2)的半年变化规律，重点讨论了电离层电场对NmF2半年变化的影响.模拟结果表明，当输入的电场没有周年和半年变化时，磁赤道地区电离层NmF2本身就具有一定的半年变化特征，而在稍高的纬度上，NmF2半年变化的强度较弱.当输入的电场具有一定的半年变化时，电离层NmF2的半年变化强度有明显的改变，且这种改变随地方时和地磁纬度不同有明显的差别.在地磁赤道附近的电离层赤道槽地区，从上午到午夜的时间内，具有半年变化的电场对电离层NmF2半年变化的强度是减弱的作用，在其他的时间内，电场对电离层NmF2半年变化强度是加强的作用.而在稍高纬度的电离层驼峰地区，情况明显不同.从上午一直到翌日日出前，具有半年变化的电场对电离层NmF2半年变化的幅度都是加强的作用.在其他的时间内，电场对电离层NmF2半年变化的幅度是减弱的作用.同时，研究表明电离层电场对NmF2半年变化的作用和“赤道喷泉”现象强烈相关.

Influence of electric fields on semiannual variations in the ionosphere at mid- and low latitudes

With a theoretic ionospheric model,we simulate semiannual variations of the ionospheric F2 region peak electron density(N-mF-2) at mid-and low latitudes under the low solar activity and quiet geomagnetic conditions,and focus on how electric fields modify the semiannual component of N-mF-2.The result indicates that when the input electric fields have no semiannual variation,the N-mF-2 at the geomagnetic equator still exhibits some semiannual component,and the amplitudes of the semiannual component become smaller as the latitude increase.When the input electric fields have a semiannual component to some extent,the amplitudes of the N-mF-2 semiannual component is strongly modified,and this influence seems to be much different at different magnetic latitudes.It is also found that the modification of electric fields on the N-mF-2 may have a close relationship with the `fountain effect' in the equatorial ionosphere.