论文部分内容阅读
A three-dimensional ray tracing study of a whistler-mode chorus is conducted fordifferent geomagnetic activities by using a global core plasma density model.For the upperbandchorus,the initial azimuthal wave angle affects slightly the projection of ray trajectoriesonto the plane(Z,((x~2+y~2))~(1/2)),but controls the longitudinal propagation.The trajectory ofthe upper-band chorus is strongly associated with the plasmapause and the magnetic local time(MLT)of chorus source region.For the high geomagnetic activity,the chorus trajectory movesinward together with the plasmapause.In the bulge region,the plasmapause extends outward,while the chorus trajectory moves outward together with the plasmapause.For moderately orhigh geomagnetic activity,the lower-band chorus suffers low hybrid resonance(LHR)reflectionbefore it reaches the plasmapause,leading to a weak correlation with the geomagnetic activityand magnetic local time of the chorus source region.For low geomagnetic activity,the lower-bandchorus may be reflected firstly at the plasmapause instead of suffering LHR reflection,exhibitinga propagation characteristic similar to that of the upper-band chorus.The results provide a newinsight into the propagation characteristics of the chorus for different geomagnetic activities andcontribute to further understanding of the acceleration of energetic electron by a chorus wave.
A three-dimensional ray tracing study of a whistler-mode chorus is conducted for differentifocal geomagnetic activities by using a global core plasma density model. For the upper bandchorus, the initial azimuthal wave angle affects slightly the projection of ray trajectoriesonto the plane (Z, (( x ~ 2 + y ~ 2)) ~ (1/2)), but controls the longitudinal propagation. the trajectory of the upper-band chorus is strongly associated with the plasma pause and the magnetic local time (MLT) of chorus source region. For the high geomagnetic activity, the chorus trajectory moves inward together with the plasmapause. in the bulge region, the plasma pause extends outward, while the chorus trajectory moves together with the plasma pause. For moderately or high geomagnetic activity, the lower-band chorus suffers low hybrid resonance (LHR) reflection before it reaches the plasmapause, leading to a weak correlation with the geomagnetic activity and magnetic local time of the chorus source region. For low geomagnetic activity, the lower-band chorus may be reflected first at the plasmapause instead of suffering LHR reflection, exhibitinga propagation characteristic similar to that of the upper-band chorus. The results provide a newinsight into the propagation characteristics of the chorus for different geomagnetic activities andcontribute to further understanding of the acceleration of energetic electron by a chorus wave.