Conjugate Effect of the 2011 Tohoku Reflected Tsunami‐Driven Gravity Waves in the Ionosphere

Abstract

Ionospheric responses to tsunamis have been investigated since the 1970s (Hines, 1972;Peltier & Hines, 1976). The modest displacement of tsunamis traveling in the open ocean surface can displace the atmosphere, transferring a fraction of energy into the atmosphere in the form of atmospheric gravity waves. The coherent tsunami oceanic waves extending extremely long distances are expected to be an ideal source to generate gravity waves since the spatial and temporal scales lie within the scales of gravity waves (Hickey et al., 2009). The characteristics of tsunami-induced gravity waves enable them to propagate upward into the thermosphere and ionosphere, altering the ionospheric plasma and producing detectable ionospheric signatures (e.g.,

Rapid Conjugate Appearance of the Giant Ionospheric Lamb Wave Signatures in the Northern Hemisphere After Hunga‐Tonga Volcano Eruptions

“…The 2011 Great Tohoku tsunami-driven gravity waves also triggered the conjugate effect (M.-Y. Chou et al, 2022), but they were mainly during nighttime. Huba et al (2015) simulated the conjugate ionospheric effects associated with the tsunami-driven gravity waves using self-consistent electrodynamics and suggested that the perpendicular neutral wind perturbation could induce polarization electric fields mapping along the geomagnetic field line to the conjugate southern hemisphere of Hawaii.…”

“…M.-Y. Chou et al (2022) discovered that the reflected tsunami was able to drive gravity waves over Japan and triggered prominent MSTID occurring in March, a season of rare MSTID occurrence, and further mapped to the conjugate southern hemisphere over Australia. However, the initial main TIDs driven by the earthquake and tsunami did not produce any conjugate effect, and the coupled gravity wave-Perkins instability may contribute to the interhemispheric conjugate process due to the specific wavefront alignment of the MSTIDs.…”

“…M.-Y. Chou et al (2022) recently showed conjugate signatures of medium-scale traveling ionosphere disturbances (MSTID) produced by the tsunami propagation during the 2011 Tohoku earthquake. However, this is the first time such conjugate behavior of ionosphere dynamo is observed in coupling with the polarization electric fields driven by the distur bance atmospheric waves from a volcanic eruption.…”

Electromagnetic conjugacy of ionospheric disturbances after the 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption as seen in GNSS-TEC and SuperDARN Hokkaido pair of radars observations

“…They showed that the neutral wind perturbations driven by AGWs lead to plasma flow variations both perpendicular and parallel to magnetic field lines, and that the electric field caused by the neutral wind perturbations propagates to the conjugate hemisphere along the magnetic field lines. Chou et al (2022) found that the equatorward and westward propagating nighttime MSTIDs appeared over Japan and Australia simultaneously associated with the tsunami oceanic waves. They interpreted that the MSTIDs could be generated by the Perkins instability including the interhemispheric coupling process.…”

Multiwave Structure of Traveling Ionospheric Disturbances Excited by the Tonga Volcanic Eruptions Observed by a Dense GNSS Network in China

“…Such conjugate TID was not observed by GNSS data in China. This is probably because that conjugate TIDs usually have limited influence area (Chou et al., 2022; Shiokawa et al., 2005). The study of the origin of the second TID is still ongoing.…”