Travelling Ionospheric Disturbances (TIDs) result from large-scale waves in the upper atmosphere somewhat analogous to ocean waves, though propagating internal to the medium rather than on the surface. By transporting energy they play a role in determining the temperature profile of the upper atmosphere. They also affect radio signals propagating through and beneath the ionosphere. Dartmouth students are involved in operating radio receivers in at least four sites in the northeastern United States, detecting TIDs through the small (0.1 Hz) Doppler shift that their ionospheric motions impose on reflecting AM radio signals. A goal is to determine many properties of the TIDs, including propagation directions and waveform shapes, from observed Doppler shifts at multiple locations.
FACULTY CONTACT: James LaBelle