Observation of Bound States and Counterrotating Lower Hybrid Eigenmodes in the Auroral Ionosphere

Definitive evidence from a plasma wave interferometer carried on a sounding rocket is presented for the observation of counterrotating electric field structures observed at frequencies above and below the local lower hybrid resonance frequency, fLHR, of the ambient plasma. These counterrotating structures were observed within the context of a lower hybrid solitary structure (LHSS), and were found to rotate in a right-handed (left-handed) sense around the geomagnetic field at frequencies above (below) fLHR, in accord with previous predictions for and observations of electric field eigenmodes within a density depletion. The presence of a narrow band feature below fLHR indicates the presence of trapped waves, and represents clear evidence of a bound state of lower hybrid waves in the auroral ionosphere.