Large-Scale Traveling Ionospheric Disturbances Observed with HamSCI Amateur Radio Using a Novel Automated Detection Technique

We present a multi-year climatology of Large Scale Traveling Ionospheric Disturbance (LSTID) period oscillations observed using 14 MHz amateur (ham) radio data. Traveling ionospheric disturbances (TIDs) are quasi periodic electron density perturbations in the F region ionosphere that affect radio communications and can help with understanding energy transport throughout the coupled magnetosphere-ionosphere-neutral atmosphere system. These are seen, in daytime, as variations in contact ranges in 14 MHz amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet), the Reverse Beacon Network (RBN), and PSKReporter. A new deterministic and fully automated method was developed for identifying and quantifying these disturbances. In this study, we present full year climatologies of LSTID events over the continental United States (CONUS) using RBN, WSPRNet, and PSK observations from 2016- 2022. Results are organized as a function wave period, amplitude, and minimum daily propagation distance. We find that LSTIDs increase in winter and decline during the fall and spring, with slight enhancements in the summer and occasional brief declines in LSTID winter activity. This seasonal pattern is consistent with previous studies and observations of LSTIDs and medium-scale TIDs, suggesting that this behavior may be associated with neutral wind filtering in the middle atmosphere, sudden stratospheric warming (SSW) events, and multi-step vertical coupling (MSVC) processes. MSVC describes the propagation of gravity waves (GWs) from the lower neutral atmosphere, their subsequent breaking, and the generation of higher-order GWs in the thermosphere, which in turn induce TIDs in the ionosphere. Furthermore, the yearly minimum propagation distance data aligns with ionospheric altitude variations that follow the solar cycle, reinforcing the connection between ionospheric dynamics and solar activity.