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

所提出的工作将集中于扩展和应用现有的电离层内中低纬度洋流系统的二维数值模型。该变网格模型基于磁场线积分量，解决了从全局到中等（5公里）电场的尺度问题。首先，该模型将用于研究引起局部太阳日落后电离层迅速上升的Sq（太阳平静）电流系统的夜间扰动。这将为Haerendel等人提出的理论提供一个自洽的数值测试。在日落后的升起。一旦全球尺度电场的数值研究完成，将采用更精细的网格来研究夜间F区等离子体中不规则性的爆炸发展，称为赤道扩散F （ESF）。虽然ESF的驱动机制（引力瑞利-泰勒不稳定性）已经被很好地理解，但不稳定性过程的启动或“播种”仍然没有确定。为了观察赤道扩散F是否由非线性一阶电场变化发展而来，最初将省略播种。然后从中性波/电离层相互作用的播种，如空间共振效应将被检查。

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.