Observation of Vertical Acoustic Resonance Effect on the Ground and in the Ionosphere During July 22 Total Eclipse
Abstract
The vertical acoustic resonance which can couple the ground, lower atmosphere and thermosphere (ionosphere) has been observed, for example, for the Mt. Pinatubo eruption in 1991 (Kanamori and Mori, 1992) and the great 2004 Sumatra earthquake (Iyemori et al., 2005). In the Mt. Pinatubo case, it was assumed that the acoustic wave (i.e., pressure variation) caused a very low frequency oscillation of the ground observed worldwide. However, a volcanic eruption or earthquake can also cause the ground oscillation directly. The ground oscillation may cause atmospheric oscillations but with a complicated causality. In the case of the Sumatra earthquake, the acoustic wave (i.e., vertical wind in the ionosphere) is assumed to be the cause of magnetic pulsations observed in Thailand. However, in this case, we have no atmospheric pressure and no appropriate ionospheric observation to validate it. When a total eclipse occurs, the rapid pressure variations over a wide area caused by the rapid decrease of temperature may also generate the acoustic resonance, however, in this case, the situation is expected to be simpler than for volcanic eruptions. This situation provides better conditions for quantitative modeling of the acoustic resonance effects. On July 22, 2009, a total eclipse was observed along a band from China, Iwo Island, and through the Tokara Islands, south of Japan. We conducted barometric, geomagnetic, temperature, GPS-TEC and HF Doppler observations at several points along the eclipse path. Because of the turbulent weather and occurrence of a magnetic storm, it is difficult to see very clear indications of the acoustic resonance in the raw pressure and magnetic field data. However, in the frequency domain, we can identify the acoustic resonance. The HF-Doppler observation also shows ionospheric oscillations in the total eclipse region. In this paper, we show the results of our observations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A12B..07I
- Keywords:
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- 2427 IONOSPHERE / Ionosphere/atmosphere interactions;
- 3384 ATMOSPHERIC PROCESSES / Acoustic-gravity waves;
- 7255 SEISMOLOGY / Surface waves and free oscillations;
- 7836 SPACE PLASMA PHYSICS / MHD waves and instabilities