Magnetic Tilt Effect on Externally Driven Electromagnetic Ion Cyclotron (EMIC) Waves

We examine coupling of fluctuations in the solar wind with electromagnetic ion cyclotron (EMIC) waves in the magnetosphere using an advanced full-wave simulation code, Petra-M. Dipole tilt dramatically affects the coupling process. While very little wave power can reach the inner magnetosphere without tilt effects, a tilted dipole field dramatically increases the efficiency of the coupling process. Solar wind fluctuations incident at high magnetic latitude effectively reaches the ground along the field line and mode-convert to linearly polarized field-aligned propagating waves at the Alfven and IIH resonances. Therefore, solar wind compressions efficiently drive linearly polarized EMIC waves when the dipole angle is tilted toward or away from the Sun-Earth direction.

Automated summary

We use the advanced full-wave simulation code Petra-M to examine the coupling of solar wind fluctuations with electromagnetic ion cyclotron (EMIC) waves in the magnetosphere. The dipole tilt has a dramatic effect on the coupling process, with a tilted dipole field increasing the efficiency of coupling. Solar wind fluctuations incident at high magnetic latitude effectively reach the ground along the field line and mode-convert to linearly polarized field-aligned propagating waves at the Alfven and IIH resonances. Therefore, solar wind compressions efficiently drive linearly polarized EMIC waves when the dipole angle is tilted toward or away from the Sun-Earth direction.