Traveling Ionospheric Disturbance (TID) from GNSS TEC observations during hurricane Ian and its Correlation to Lower Atmosphere Gravity Waves

Hurricanes can produce traveling ionospheric disturbances (TIDs) that affect GNSS systems by creating gravity waves and mesoscale disturbances that propagate upward and perturb the ionosphere. Understanding vertical connection from the lower atmosphere to the ionosphere requires quantifying these event-time signatures and separating them from background MSTID variability.
We examine TIDs during Hurricane Ian on 28 September 2022 using ground-based GNSS total electron content (TEC) observations over the contiguous United States (CONUS; 20–55°N, 100–65°W). Slant TEC is converted to vertical TEC perturbations (dTEC) at ionospheric pierce points (IPPs) using standard quality controls. Wave-like perturbations are isolated by removing slow background variations and applying a Butterworth band-pass filter targeting MSTID-scale periods. Disturbance intensity and propagation are characterized using running RMS of band-passed dTEC and storm-centered distance–time (r–t) diagrams, including azimuthal-sector r–t diagrams to evaluate directionality.
Enhanced nighttime-sector wave activity is observed, with the largest RMS typically occurring at radial distances of ~1000–2000 km from the hurricane center. The r–t diagrams show coherent sloped ridges consistent with outward-propagating disturbances. From ridge slopes we estimate horizontal phase speeds of ~150–250 m s⁻¹, characteristic wavelengths of ~800–1200 km, and dominant periods in the 20–40 min band, with weaker modulation on ~1–2 h timescales.
We compare concentric CTID activity from GNSS dTEC with lower-atmosphere concentric gravity-wave activity obtained from satellite observation data to assess vertical coupling. We quantify correlation using temporal alignment of wave packets and spatial co-location of wave epicenters. This effort will improve our understanding of the interaction between the lower and upper atmosphere through gravity wave propagation.