Ocean‐Ionosphere Disturbances Due To the 15 January 2022 Hunga‐Tonga Hunga‐Ha'apai Eruption

We investigate the oceanic and ionospheric response in New Caledonia-New Zealand and Chile-Argentina to the 15 January 2022 Hunga-Tonga volcanic eruption. For the first time, we highlight a reversed response in the oceans and in the ionosphere in terms of the amplitudes. The sea-surface fluctuations due to the passage of the atmospheric Lamb wave (i.e., air-sea wave) were not remarkable while the related ionospheric perturbation was considerable. Reversely, the eruption-induced tsunami ("regular" tsunami) caused major variations in sea-surface heights (similar to 1 m near the volcano and similar to 2 m along the Chilean coastline), whereas the associated ionospheric perturbation was quite small. The observed large-amplitude ionospheric response due to Lamb waves propagation is difficult to explain, and the coupling between the Lamb wave and the ionosphere is not well-understood yet. For the first time, we estimate the delay between the Lamb waves and their signatures in the ionosphere to be similar to 12-20 min.