Direct observation of an interaction in magnetosphere



Researchers have now directly observed an interaction between poloidal waves, a type of ultralow-frequency oscillation of the Earth's geomagnetic fields, and ions in the ring current, a band of charged particles drifting around Earth in the magnetosphere above the equator. This so-called drift resonance wave-particle interaction has been studied theoretically, and some modes of the interaction (in particular the second harmonics, similar to higher-frequency vibrations of a vibrating string) have been reported in spacecraft observations, but the first fundamental mode resonances of this interaction had not been clearly observed.