A statistical study of interhemispheric comparison of dipole tilt angle effect on the latitude of the mid-altitude cusp is preformed by a data set of the Cluster cusp crossings over a 5-year period. The result shows t...A statistical study of interhemispheric comparison of dipole tilt angle effect on the latitude of the mid-altitude cusp is preformed by a data set of the Cluster cusp crossings over a 5-year period. The result shows that the dipole tilt angle has a clear control of the cusp latitudinal location. When the dipole tilts sunwards, the cusp is shifted poleward. The northern cusp moves 1° ILAT for every 15.4° increase in the dipole tilt angle, while the southern cusp moves 1° ILAT for every 20.8° increase in the dipole tilt angle. This suggests that an interhemispheric difference appears in the dependence of cusp latitudinal location on the dipole tilt angle.展开更多
The EISCAT data are used to confirm the important role of precipitation particles in the ionization rate in the auroral region. The height range of the effective ionization is quite different for particles with differ...The EISCAT data are used to confirm the important role of precipitation particles in the ionization rate in the auroral region. The height range of the effective ionization is quite different for particles with different energies. On the other hand, an enhancement of magnetospheric convection often results in decreasing of electron density, N , in the F layer. During January 28￣29,1985, the disturbed profiles of N were very typical, in which N m(E layer) N (F layer) and N decreased with height above 147 km. This phenomenan is caused by both energetic particles and intensive convection. During the period of February 16￣17, 1993, however, the N (F layer) increased extremely, while N (E layer) remained low. This is also a typical profile, but is opposite to the former one. In this case,the particles with lower energy (<1 keV) in the magnetosheath enter directly the high latitude ionosphere through the cusp,and can contribute significantly to the F layer ionization content.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 40674091 and 40621003, and the CAS International Partnership Programme for Creative Research Teams.
文摘A statistical study of interhemispheric comparison of dipole tilt angle effect on the latitude of the mid-altitude cusp is preformed by a data set of the Cluster cusp crossings over a 5-year period. The result shows that the dipole tilt angle has a clear control of the cusp latitudinal location. When the dipole tilts sunwards, the cusp is shifted poleward. The northern cusp moves 1° ILAT for every 15.4° increase in the dipole tilt angle, while the southern cusp moves 1° ILAT for every 20.8° increase in the dipole tilt angle. This suggests that an interhemispheric difference appears in the dependence of cusp latitudinal location on the dipole tilt angle.
文摘The EISCAT data are used to confirm the important role of precipitation particles in the ionization rate in the auroral region. The height range of the effective ionization is quite different for particles with different energies. On the other hand, an enhancement of magnetospheric convection often results in decreasing of electron density, N , in the F layer. During January 28￣29,1985, the disturbed profiles of N were very typical, in which N m(E layer) N (F layer) and N decreased with height above 147 km. This phenomenan is caused by both energetic particles and intensive convection. During the period of February 16￣17, 1993, however, the N (F layer) increased extremely, while N (E layer) remained low. This is also a typical profile, but is opposite to the former one. In this case,the particles with lower energy (<1 keV) in the magnetosheath enter directly the high latitude ionosphere through the cusp,and can contribute significantly to the F layer ionization content.
