hide
Free keywords:
-
Abstract:
We use high temporal-resolution mesoscale imagery from the Geostationary Operational Environmental Satellite-R (GOES-R) series to track the Lamb and gravity waves generated by the January 2022 Hunga Tonga-Hunga Ha’apai eruption. The 1-min cadence of these limited area (~1,000x1,000 km2) brightness temperatures ensures an order of magnitude better temporal sampling than full-disk imagery available at 10-min or 15-min cadence. We show that previous studies using the low-cadence full-disk data considerably overestimated the horizontal wavelength (~400–500 km) and period (~20–30 min) of the Lamb wave due to spatiotemporal aliasing. The 1-min imagery reveals a leading Lamb wave with a wavelength of only ~130 km and trailing waves with even shorter wavelengths of ~40–80 km. The characteristic propagation speed is estimated at ~315±15 m s-1, resulting in typical periods of 2–7 min. From the time of appearance of the first detectable Lamb wave, we derive an emission time of ~04:07 UTC for the primary pressure pulse. Weaker Lamb waves were also emitted by the last major eruption at ~08:40–08:45 UTC, which were, however, only identified in the near field but not in the far field. We also noted wind effects, such as mean flow advection and critical level filtering in the propagation of concentric gravity wave rings and observed gravity waves traveling near their theoretical maximum speed.
