分类: 地球科学 >> 空间物理学 提交时间: 2017-01-22
摘要: High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere, and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well. The High-Energy Electron Flux (HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed together with the data of nearsurface atmospheric vertical electric field measured at the Russian Vostok Station. Three HEEF enhancements are identified and it is shown that when the HEEF increases to a certain level, the local atmospheric vertical electric field near the ground can increase substantially than usual. The response time of the electric field to HEEF enhancement is about 3.7 to 4 days.
分类: 地球科学 >> 空间物理学 提交时间: 2017-01-22
摘要: By use of the global PPMLR Magnetohydrodynamics(MHD) model, a serial of quasi-steady-state numerical simulations were conducted to examine the modulation property of the interplanetary magnetic field clock angle theta on the solar wind energy input into the magnetosphere. All the simulations can be divided into seven groups according to different criteria of solar wind conditions. For each group, 37 numerical examples are analyzed, with the clock angle varying from 0�to 360�with an interval of 10� keeping the other solar wind parameters(such as the solar wind number density, velocity, and the magnetic field magnitude) unchanged. As expected, the solar wind energy input into the magnetosphere is modulated by the IMF clock angle. The axisymmetrical bell-shaped curve peaks at the clock angle of 180� However, the modulation effect remains invariant with varying other solar wind conditions. The function form of such an invariant modulation is found to be sin(0/2)2.70 + 0.25.