Seasonal Climatology of Ionospheric Variability with MSTID Periods Observed Using HamSCI Grape HF Doppler Receivers

Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are quasi-periodic variations in ionospheric electron density that are often associated with atmospheric gravity waves. MSTIDs cause amplitude and frequency variations in radio waves that refract off the ionosphere. Typical MSTIDs exhibit wavelengths of 50-500 km and periods of 15-60 minutes. The authors present an analysis of observations of MSTIDs made with a network of Ham Radio Science Citizen Investigation (HamSCI) Low Cost Personal Space Weather Stations (PSWS), located throughout the continental United States. The MSTIDs were detected in the Doppler shift of the received carrier of radio station WWV. WWV is a frequency, and time, standard transmitting station located near Fort Collins, Colorado, USA. By analyzing the Power Spectral Density (PSD) of oscillations received by the Doppler-shifted carrier wave, we demonstrate a method to determine the seasonal variation climatology of MSTIDs. Initial results suggest enhanced MSTID activity is observed at dawn and dusk, as well as through the pre-midnight period. Dawn and dusk MSTID enhancements are consistent with Atmospheric Gravity Waves (AGWs) generated by the terminator.