ULF power fluctuations in the solar-wind parameters and their relationship with the relativistic electron flux at the geosynchronous orbit

摘要

We focused the attention on the Pc5 geomagnetic pulsations in response to the solar wind forcing and their relationship with the relativistic electron flux at geostationary orbit. We present here the results of a correlation analysis between the Pc5 power in the magnetosphere and on the ground, at low and high latitude, and the solar-wind speed and fluctuation power of the interplanetary magnetic field and solar-wind dynamic pressure through the years 2006 to 2010, also showing the relative timing between pulsations and solar-wind parameters. The Pc5 power appears significantly correlated with simultaneous solar-wind pressure fluctuations and with the solar-wind speed lagged by several hours. The relative amplitude of the two correlation peaks depends on the solar cycle phase and on the latitude. We also show a strong relationship between the Pc5 power and the > 600 keV and > 2MeV electron flux at geosynchronous orbit. Clear evidence emerges that the electron flux follows the Pc5 power by about 2 days; the time delay is a bit longer for the higher-energy electrons.