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Ionospheric ripples excited by superimposed wave fronts associated with Rayleigh waves in the thermosphere
Author(s) -
Kakinami Yoshihiro,
Kamogawa Masashi,
Watanabe Shigeto,
Odaka Masatsugu,
Mogi Toru,
Liu JannYenq,
Sun YangYi,
Yamada Takuji
Publication year - 2013
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/jgra.50099
Subject(s) - rayleigh wave , geology , rayleigh scattering , point source , asymmetry , seismology , excited state , surface wave , epicenter , ionosphere , geophysics , acoustic wave , physics , geodesy , optics , atomic physics , quantum mechanics
Coseismic ionospheric disturbances (CIDs) associated with the 2011 Tohoku earthquake off the Pacific coast ( M w 9.0, Tohoku EQ) were examined using total electron content and seismic wave data. A faster CID propagated at ~3.0 km/s only in the west‐southwest, while a slower CID propagated concentrically at 1.2 km/s or slower from the tsunami source area. Taking the propagation speed and oscillation cycle into account, the faster CID was associated with a Rayleigh wave, but the slower CID was associated with an acoustic or gravity wave. The north‐south asymmetry of the CID associated with the Rayleigh wave suggests that the Rayleigh wave did not act as a point source of the acoustic wave because a point source propagating in all directions must produce symmetric CID in all directions. Therefore, a superimposed wave front of acoustic waves was excited by the Rayleigh wave and produced the north‐south asymmetry of the faster CID due to the magnetic inclination effect, which is different from a well‐known north‐south asymmetry of CID excited at the epicenter. On the other hand, above and south of the tsunami source area, the CID with a period of 4 min was excited by a point source located at the tsunami source area because atmospheric waves propagating from a point source produce north‐south asymmetry in the resulting CID.