资源环境科技发展态势分析平台

We investigate the propagation characteristics of low-altitude hiss in the ionosphere by numerical simulation with a two-dimensional full-wave model. The simulation results demonstrate that linear mode conversion from whistler to H+ band electromagnetic ion cyclotron wave and polarization reversal occur simultaneously where wave frequency matches the H+-He+ crossover frequency. This mode conversion efficiency shows sensitive dependence on wave normal angle and plays a significant role in the propagation of whistler emission near the local proton gyro-frequency in the ionosphere by redistributing the wave energy below and above the H+-He+ cutoff frequency, which can explain the low-altitude hiss observed by the Freja and Detection of Electromagnetic Emissions Transmitted from Earthquake Regions satellites, respectively. The energy of whistler-mode low-altitude hiss emission can be transferred to reflected left-hand polarized electromagnetic ion cyclotron through mode conversion and the efficiency reaches a maximum for intermediate incident wave normal angle (of 45 degrees).