Geostationary satellites reveal long‑range transport of internal gravity waves from the November 2025 Haily Gubbi eruption

The 23 November 2025 eruption of the Haily Gubbi volcano in Ethiopia generated internal gravity waves that were analyzed using combined observations from the geostationary satellites Himawari‑8 and Meteosat‑9. Several hours of sustained plume emission produced a wave packet embedded within SO₂‑rich volcanic air masses, which propagated eastward under strong mid‑ to upper‑tropospheric westerlies. The propagation direction and phase speed matched the 300‑hPa wind field, indicating advection along the subtropical jet. Exceptionally dry conditions within the jet core (relative humidity < 30%) likely helped maintain the volcanic plume and prevented attenuation of the wave signal during long‑range transport. No clear signatures were detected in channels sensitive to the lower troposphere or stratosphere, reflecting the absence of an unstable layer capable of forming a wave duct. Without ducting, vertical leakage of wave energy inhibited downward penetration, explaining the lack of detectable signals over Japan in lower‑tropospheric channels. The combined satellite observations show that the wave packet propagated primarily within a narrow mid‑ to upper‑tropospheric layer constrained by background wind and humidity structure. These results demonstrate the value of multi‑satellite observations for detecting eruption‑generated internal gravity waves and highlight the environmental conditions that enable their long‑distance transport.