2022 Tonga volcanic eruption induced global propagation of ionospheric
disturbances via Lamb waves
Abstract
The Tonga volcano eruption at 04:14:45 UT on 2022-01-15 released
enormous amounts of energy into the atmosphere, triggering very
significant geophysical variations not only in the immediate proximity
of the epicenter but also globally across the whole atmosphere. This
study provides a global picture of ionospheric disturbances over an
extended period for at least four days. We find traveling ionospheric
disturbances (TIDs) radially outbound and inbound along entire
Great-Circle loci at primary speeds of ~300-350 m/s
(depending on the propagation direction) and 500-1000 km horizontal
wavelength for front shocks, going around the globe for three times,
passing six times over the continental US in 100 hours since the
eruption. TIDs following the shock fronts developed for
~8 hours with 10-30 min predominant periods in near- and
far- fields. TID global propagation is consistent with the effect of
Lamb waves which travel at the speed of sound. Although these
oscillations are often confined to the troposphere, Lamb wave energy is
known to leak into the thermosphere through channels of atmospheric
resonance at acoustic and gravity wave frequencies, carrying substantial
wave amplitudes at high altitudes. Prevailing Lamb waves have been
reported in the literature as atmospheric responses to the gigantic
Krakatoa eruption in 1883 and other geohazards. This study provides
substantial first evidence of their long-duration imprints up in the
global ionosphere. This study was enabled by ionospheric measurements
from 5,000+ world-wide Global Navigation Satellite System (GNSS) ground
receivers, demonstrating the broad implication of the ionosphere
measurement as a sensitive detector for atmospheric waves and
geophysical disturbances.