大气重力波触发的Rayleigh－Taylor不稳定性的时空演变

SPATIAL AND TEMPORAL EVOLUTION OF THE RAYLEIGH-TAYLOR INSTABILITY INITIATED BY ATMOSPHERIC GRAVITY WAVES

对大气重力波触发的赤道电离层Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性的时空演变进行了数值模拟．结果表明，重力波能在Ｆ区底部触发Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性，这种等离子体不稳定扰动穿过Ｆ峰，到达Ｆ区顶部，形成等离子体泡结构．等离子体泡出现向西倾斜和分岔等特征．当夜Ｆ区较高时，产生等离子体泡的时间仅１９００ｓ．数值模拟结果证实了重力波触发．Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性的理论，解释了大量电离层观测现象．

Numerical simulations of spatial and temporal evolution of the Rayleigh-Taylor instability initiated by atmospheric gravity waves are performed.It is shown that gravity waves can initiate the Rayleigh-Taylor instability in the bottomside F region and the initiated instability evolves into plasma bubbles.The westward tilt and bifurcation of the plasma bubbles are reproduced in the simulations.The production and rise time of the plasma bubbles initiated by gravity waves is only 1900 seconds when the altitude of the F region is high.The numerical simulations in the present paper verify the theory that gravity waves can produce large scale equatorial spread F irregularities and shows a good agreement with the ionospheric phenomena observed.