DE‐1 and COSMOS 1809 observations of lower hybrid waves excited by VLF whistler mode waves

Abstract

Past work demonstrates that strong lower hybrid (LH) waves can be excited by electromagnetic whistler mode waves throughout large regions of the topside ionosphere and magnetosphere. The effects of the excited LH waves upon the suprathermal ion population in the topside ionosphere and magnetosphere depend upon the distribution of LH wave amplitude with wavelength λ. The present work reports plasma wave data from the DE‐1 and COSMOS 1809 spacecraft which suggests that the excited LH wave spectrum has components for which λ ≤3.5 m when excitation occurs at a frequency roughly equal to the local lower hybrid resonance frequency. This wavelength limit is a factor of ∼3 below that reported in past work and suggests that the excited LH waves can interact with suprathermal H+ ions with energy ≤6 eV. This finding supports recent work concerning the heating of suprathermal ions above thunderstorm cells.