Advanced Model of the Low Latitude Current Systems in the Ionosphere: The Evening Anomaly and Equatorial Spread F

拟议的工作将侧重于推广和应用现有的电离层内中低纬潮汐电流系统的二维数值模式。该变网格模型以磁力线积分量为基础，求解了从全球向下到中(5公里)的电场尺度。首先，该模式将被用来研究晚间对SQ(太阳安静)电流系统的扰动，该系统是导致局部太阳日落后电离层迅速上升的原因。这将为Haerendel等人提出的理论提供一个自洽的数值测试。？1990年！在日落后的日出上。一旦全球尺度电场的数值研究完成，将使用更精细的网格来研究称为赤道扩展F(ESF)的夜间F区等离子体中不规则的爆炸性发展。虽然对ESF的驱动机制(引力瑞利-泰勒不稳定性)已有很好的了解，但不稳定过程的启动或“播种”仍未确定。最初，将省略播种，以查看赤道扩散F是否由非线性一阶电场变化发展而来。然后，将检查来自中性波/电离层相互作用的播种，例如空间共振效应。

The proposed effort will focus on extension and application of an existing, two-dimensional, numerical model of the mid- and low-latitide current systems within the ionosphere. This variable-grid model is based on magnetic field-line integrated quantities and solves for scales from global down to medium (5km) electric fields. First, the model will be used to investigate the evening perturbation to the Sq (solar quiet) current system which is responsible for the rapid rise of the ionosphere after local solar sunset. This will provide a self-consistent numerical test of the theory presented by Haerendel et al. ?1990! on the post-sunset rise. Once the numerical study of the global scale electric field is completed, a finer grid will be employed to investigate the explosive development of irregularities within the evening F Region plasma called Equatorial Spread F (ESF). While the driving mechanism of ESF is well understood (gravitational Rayleigh-Taylor instability), the initiation or "seeding of the instability process is still not established. Initially, seeding will be omitted to see if Equatorial Spread F develops from the nonlinear first order electric field variation. Then seeding from neutral- wave/ionosphere interactions such as spatial resonance effects will be examined.