等离子体对流对极区电离层F2层的峰值影响研究

Polar plasma convection will cause significant changes in ionospheric electron density, and it has significant effects on our communication, navigation, and space systems.Limited by the conditions of observation, more studies are needed to analyze influences of the plasma convection on the F2 layer peak electron density in polar region. Problems that needed to be solved include that: how does the ionospheric F2 layer peak electron density response to plasma convection under complex conditions,what will happen on F2 layer peak electron density under some special plasma structures caused by convection，The relative importance of plasma convection and particle precipitation to the peak of F2 layer. Based on long term observations of ionosphere in polar region, we will make a systematic study on basic physical process in polar ionosphere in this project. The research contents include: (1) studying responses of ionospheric F2 layer peak electron density to varied convection structures with different Interplanetary Magnetic Field in cusp region; (2) analysing the motion features of polar cap patches and studying response of F2 layer to special plasma structures caused by convection; (3) simulating typical ionospheric features by using a High-latitude Ionospheric Model，and studying the relative importance of each physical process in the formation of F2 layer peak.This project will provide theoretical reference for distinguishing the basic physical processes in polar ionosphere.

在极区，等离子体对流会引起电离层电子密度的大幅度改变，对人类通信、导航和航天系统等产生重大影响。受观测条件所限，等离子体对流对极区F2层的峰值影响研究还面临着一些问题，如：复杂条件下极区电离层F2层峰值对等离子对流的响应、对流引起的电离层不均匀体对F2层峰值的影响以及不同太阳活动和季节条件下，等离子体对流与粒子沉降对F2层峰值的相对贡献等。本项目拟利用南北极长期对电离层的联合观测数据，对极区电离层中的基本物理过程进行深入研究：（1）研究不同行星际磁场条件下，对流模式变化对极隙区F2层峰值出现时刻与强弱的影响；（2）通过分析电离层不均匀体的运动状况与F2层电子密度的变化，研究对流引起的特殊电离层结构对F2层峰值的影响；（3）利用一个高纬电离层模型对极区F2层的峰值分布进行模拟再现，与观测结果进行对比，研究不同物理过程对F2层峰值的相对贡献。本项目将为区分极区电离层中的基本物理过程提供参考。

极区电离层F2层峰值电子密度（NmF2）受太阳辐射、等离子体对流和能量粒子沉降的共同作用，形态特征极其复杂，本项目针对等离子体对流在不同时间周期上对极区电离层F2层峰值的影响开展了研究。本项目采用能够间接反映等离子体对流模式的行星际磁场（IMF）数据和能直观绘制对流图像的南北极SuperDARN雷达观测数据，研究了极隙区与极光带纬度NmF2对行星际磁场 Bz分量的响应，分析了逆阳对流在极隙区纬度和极光带纬度电离层日侧峰值形成过程的不同贡献。研究了太阳活动高年冬季极区电离层NmF2的日变化峰值随等离子体对流图像的分布，探讨了北极极光带与极隙区纬度NmF2在日变化中双峰结构的不同成因。利用国际参考电离层IRI-2016模型对整个太阳活动周时间尺度的极区电离层NmF2数据进行了模拟，与观测数据开展了对比研究。在整个太阳活动周时间范围内较为系统地探讨了太阳辐射、等离子体对流及能量粒子沉降等不同物理过程对极区电离层NmF2的相对贡献，为极区电离层建模工作提供了改进依据。