中纬电离层大尺度扰动的数值模拟

利用计算机模拟研究了不同条件下中纬电离层F区大尺度扰动的时空演变.当存在幅度约为5％的初始扰动时,Perkins不稳定性能发展成为大尺度电离层不均匀体.大气重力波能触发Perkins不稳定性,在更短时间内增长成为大幅度电离层振荡.非均匀局部电场结构也能产生局部电离层的大幅度扰动.本义的模拟表明,中纬电离层大尺度扰动主要表现为磁通管内等离子体沿磁力线的振荡.模拟结果与观测现象符合得很好.

NUMERICAL SIMULATIONS OF LARGE SCALE PERTURBATIONS IN THE MIDLATITUDE F REGION

We have performed numerical simulation of spatial and temporal evolution oflarge scale perturbations in the ionospheric F region at midlatitude under differentconditions. It is found that the Perkins instability can evolve into large scaleirregularities when there exist initial density perturbations with amplitude of about5%. Atmospheric gravity waves can initiate the Perkins instability. After initiation,the Perkins instability grows into large amplitude oscillations of the F layer. Localirregular electric fields may result in large amplitude perturbations of local ionospherealso. It is shown that large scale perturbations at the midlatitude F region appearmainly as oscillations of the F layer along the magnetic field lines. The numerical re-sults are in good agreement with observations.