Decrease of keV electron and ion fluxes in the dayside magnetosphere during the early phase of magnetospheric disturbances

摘要: Abstract We demonstrate that a decrease of the keV particle fluxes in dayside magnetosphere near geosynchronous orbit is characteristic first several hours magnetospheric disturbances. After some newly injected plasma from nightside reaches ‘evacuated’ regions and strong flux increases are observed. The high altitude observational results reported here agree well with earlier measurements ionosphere. ‘evacuation’ interpreted terms change convection pattern associated an increase large scale electric field at onset disturbance. model presented capable accommodating all characteristics data, such as temporal spatial distributions, energy pitch angle characteristics, differences between electrons protons.