一个低纬电离层理论模式

建立一个改进的低纬F层时变理论模式．采用沿磁力线分布的固定网格点，利用算子分裂方法求解离子连续性和动量方程，给出O＋、N2＋、O2＋和NO＋密度随纬度、高度变化的二维分布．对太阳活动高年的春分季节东亚区赤道异常日变化进行的模拟计算，较好地再现了赤道异常的典型特征．计算结果也表明HWM90模式给出的低纬夜间风速可能偏大；东亚区垂直漂移速度可能比美洲区的要小．

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.