极区电离层不均匀体所引起电离层闪烁研究

The polar region is the natural window of Earth open to interplanetary space, where the Earth's magnetic field lines are highly convergent, and various dynamical processes generated by the solar wind-magnetosphere coupling can be directly mapped to the polar ionosphere. This often results in various irregularities and complicated plasma convection in the polar ionosphere, which are often associated with strong ionospheric scintillations and affect the communication and navigation. However, it is far from wellknown of the distributions and generation mechanisms of the scintillation in the polar ionosphere and is difficult to forcast, due to the formation and evolution processes of the various irregularities often affected and modulated by the various dynamical proceses. The proposal is planning to analyze the relationship between the polar ionospheric scintillations and various irregularities, to find out the role of the physical mechanism of density gradient instability and flow shear instability in the generation and evolution of the scintillations, to show a quasi-real-time distribution map of the scintillations in a large area of the polar ionosphere, and find way to do the scintillation modeling and try to establish a new scintillation model for the polar ionosphere, by using largely coveraged data from GPS TEC and scintillation receivers, coordinated the observations from the all sky imagers at Chinese Yellow River Station and Zhong Shan Station and other stations, and from SuperDARN and EISCAT radars, and combining the relevant polar ionospheric models and scintillation models.

极区是地球开向太空的天然窗口，地球磁力线在极区高度汇聚，太阳风-磁层耦合过程中的各类动力学过程可直接映射到极区电离层，在极区电离层形成众多的不均匀体结构和伴随有复杂的对流过程。这些不均匀体结构常常引起很强的电离层闪烁，影响通讯导航质量。然而，由于这些不均匀体的形成和演化过程极易受各类动力学过程影响和调制，因而其所引起的闪烁特征、产生机理至今仍不清楚，准确建模预报十分困难。本项目拟充分利用极区广覆盖的GPS TEC和电离层闪烁的观测，联合我国北极黄河站、南极中山站全天空成像仪等的观测和SuperDARN及EISCAT雷达等的观测数据，结合极区电离层理论和闪烁模型，深入研究极区电离层闪烁与各类不均匀体结构之间的关系，探讨梯度漂移和速度剪切不稳定性等物理机制在闪烁产生和演化过程中的作用，给出极区大范围电离层闪烁准实时分布图，探索极区大范围的闪烁建模方法，并尝试开发出极区电离层闪烁预报模型。

极区电离层是日地能量耦合系统中的重要一环，地球磁力线在极区几近垂直进出并向太空开放。因而，各类太阳风-磁层-电离层耦合动力学过程能沿着磁力线映射到极区电离层，进而产生各种不同尺度的不均匀体，例如等离子体云块、极盖区极光弧等。这些不均匀体边缘常常在各类不稳定过程的作用下形成众多微小尺度的不均匀体，进而引起电离层闪烁，使得极区电离层成为地球上两大闪烁高发区之一。由于极区电离层扰动和闪烁会极大影响人类的航空航天活动，对极地通讯、导航、定位等产生强烈干扰。因而，亟需开展极区电离层中不同尺度不均匀体研究及其引起的电离层闪烁监测、建模工作。本项目利用极区电离层全域GPS接收机数据、SuperDARN对流数据、非相干散射雷达和全天空相机观测，结合DMSP/Swarm等电离层卫星的实地监测，结合理论模型和数值模拟，深入研究极区电离层各个尺度不均匀体的形成与演化过程，统计不同太阳活动、地磁条件下的时空分布和等离子体参量特征；统计分析各个尺度不均匀体是否伴随、引起电离层闪烁，其时空分布与不均匀体具有怎样的关联性；探讨、分析不同的不均匀体中，梯度漂移和速度剪切不稳定性等物理机制对电离层闪烁的控制作用；利用大范围 GPS-TEC和闪烁数据，获得极区电离层不均匀体引起的闪烁大范围分布图，并探索极区大范围的闪烁建模方法。