Dartmouth Events

Abstract: The transmission of terrestrial VLF emissions through the ionosphere has a measurable and often significant effect upon both energetic and relativistic electron populations in the magnetosphere. Both natural (e.g. lightning transients) and artificial (e.g. ground VLF transmitter radiation) sources contribute significantly to these VLF emissions. Models exist of this VLF penetration process, and satellite measurements show the spatial and diurnal variations in wave amplitudes at the upper bounds of the ionosphere (600-800 km altitude).  However, no measurements of the actual electrodynamics of the attenuation and propagation process from the interior of the Earth-Ionospheric waveguide, through its boundary in the D and E region of the ionosphere, and into the ionosphere and magnetosphere above currently exist.

With this deficit in the observational database in mind, we proposed to fly a fully 3D EM field measurement and relevant plasma, and neutral particle measurements at mid-latitudes through the radiation fields of an existing VLF transmitter (USN call sign NAA; 24 kHz; Cutler, Maine) in order to explore the electrodynamics of the VLF absorption, reflection, and transmission process.

For the Dartmouth Space and Plasma Seminar, I’ll present a summary of the rationale behind VIPER, the in situ and remote sensing instrumentation to be flown and fielded in support of the campaign, the expected results, and likely follow on campaigns to continue this exploration.