Simultaneous ground-based observations of electric and magnetic field variations near the magnetic equator for space weather study

In order to clarify the global nature of penetration mechanism of DP 2 electric fields from the polar to the day- and night-side equatorial ionospheres, and to understand the solar wind-Earth's magnetosphere coupling as a space weather study, we have carried out simultaneous magnetic and electric field observations using the Frequency Modulated-Continuous Wave (FM-CW) HF radar and the Circum-pan Pacific Magnetometer Network. The DP 2 electric fields caused by the solar wind interaction with the Earth's magnetic field may be imposed on the polar ionosphere, and the ionospheric DP 2 electric fields are penetrating instantaneously from the polar ionosphere into both the day- and night-side equatorial regions.