电离层加热实验中反射高度下降特征的数值模拟

摘要

Enhanced ion and plasma lines can be observed by the ground-based incoherent radar when high power HF waves were transmited into ionosphere.An ionospheric heating experiment was carried out in the fall of 2010,Norway.The long-lived enhanced ion and plasma lines were first observed in this ex-periment,and this may be caused by the Parametric Decay Instability (PDI).In addition,the VHF data show that the enhanced lines are descending in altitude with time during the heater-on period.The possible cause for the descending altitude may be the enhanced electron diffusion.In this paper,the reflection height is simulated based on the parameters of modified IRI and MSISE models,and results show that the reflection height can be descent with time due to the enhanced diffusion.A good agreement is obtained be-tween the simulation and experiment,thus the hypothesis is proved to be reliable.%向电离层中注入大功率电磁波可引发地基非相干散射雷达观测的离子线和等离子体线回波功率增强现象.2010年秋季，在挪威开展了极区电离层离子线与等离子体线增强特征激发实验.实验中首次得到了 VHF 雷达观测的长生命周期的增强特征，该现象系由参量衰变不稳定性引起的.另外，增强现象所处高度随加热的进行呈下降趋势，针对该特征文章给出了可能的物理机制，即该现象系由泵波促使反射高度附近的电子扩散效应增强引起的.文章利用修正的 IRI 和 MSISE 模型参数对加热实验中的反射高度阶跃性下降特征进行了仿真，仿真结果表明，加热电波引起的电子扩散效应可以使得反射高度下降，并且下降的高度与实验结果吻合较好，验证了该物理机制的可能性.