Climatology of Large-Scale Traveling Ionospheric Disturbances Observed with 14 MHz 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. This technique, which filters for TID wave periods between 1 and 5 hours and curve fits a sinusoidal function to the first hop skip-distance edge of observed communication ranges, provides both TID amplitudes and periods. 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- 2021. Results are organized as a function wave period, amplitude, and season. 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 shows consistency with previous studies and observations of LSTIDs and medium scale TIDs that suggests 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 is a process where gravity waves (GWs) from the lower neutral atmosphere propagate upwards, break, and produce new, higher-order GWs in the thermosphere and TIDs in the ionosphere.