Ionospheric effects of ground motion: The roles of magnetic field and nonlinearity

Ostrovsky, Lev A.

doi:10.1016/j.jastp.2008.03.017

Cited by 9 publications

(6 citation statements)

References 21 publications

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“…The acoustic wave propagated across the magnetic field lines and then excited an ion acoustic wave through the collision. The interaction between acoustic waves and magnetosonic waves in the ionosphere has been discussed [ Aburjania and Machabeli , ; Ostrovsky , ]. The results suggest that plasma perturbation might be excited by the acoustic wave generated by the rocket.…”

Section: Discussionmentioning

confidence: 99%

Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012

et al. 2013

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[1] Ionospheric disturbances caused by a missile launched from North Korea on 12 December 2012 were investigated by using the GPS total electron content (TEC). The spatial characteristic of the front edge of V-shaped disturbances produced by missiles and rockets was first determined. Considering the launch direction and the height of estimated ionospheric points at which GPS radio signal pierces the ionosphere, the missile passed through the ionosphere at heights of 391, 425, and 435 km at 0056:30, 0057:00, and 0057:30 UT, respectively. The observed velocities of the missile were 2.8 and 3.2 km/s at that time, which was estimated from the traveling speed of the front edge of V-shaped disturbances. Westward and eastward V-shaped disturbances propagated at 1.8-2.6 km/s. The phase velocities of the westward and eastward V-shaped disturbances were much faster than the speed of acoustic waves reported in previous studies, suggesting that sources other than acoustic waves may have played an important role. Furthermore, the plasma density depletion that is often observed following missile and rocket launches was not found. This suggests that the depletion resulting from the missile's exhaust was not strong enough to be observed in the TEC distribution in the topside ionosphere.

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Section: Discussionmentioning

confidence: 99%

Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012

et al. 2013

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“…The observed spreading of the positive and negative phases of the slow ionospheric response can be attributed to the different speed of propagation for the positive and negative phases of the initial atmospheric disturbance (i.e., the compression‐rarefaction phases of the acoustic N wave). At some altitude where the magnetic pressure dominates the thermal pressure (at about 160–170 km) an acoustic wave propagating upward from the ground to ionospheric level transforms into the fast magnetic sound which is the same wave mode as the nonmagnetic sound [ Ostrovsky , 2008]. In cases in which magnetic forces dominate the displacement of plasma becomes mostly in direction across the magnetic field due to “frozen‐in” condition.…”

Section: Discussionmentioning

confidence: 99%

Two‐mode long‐distance propagation of coseismic ionosphere disturbances

et al. 2009

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[1] Using GPS total electron content (TEC) measurements, we analyzed ionosphere response to the great Kurile earthquake of 4 October 1994. High spatial resolution of the Japanese dense array of GPS receivers (GEONET) provided us the unique opportunity to observe the evolution of coseismic ionospheric disturbances (CID), which propagated for more than 1800 km away from the epicenter. Plotting a traveltime diagram for the CID and using an ''array processing'' technique within the approximation of a spherical CID wavefront, we observed a phenomenon of CID separation into two modes and we found that characteristics of the CID depend on the distance from the epicenter. The maximum of the CID amplitude was observed at $500 km from the epicenter. Within the first 600-700 km, the CID propagation velocity was about 1 km/s, which is equal to the sound speed at the height of the ionospheric F-layer. Starting from $600 to 700 km out from the epicenter, the disturbance seems to divide into two separate perturbations, with each propagating at a different velocity, about 3 km/s for the one and about 600 m/s for the other. Apparently, the TEC response in the far-field of the CID source is a mixture of signals that further ''splits'' into two modes because of the difference in their velocities. Our observations are in good agreement with the results of space-time data processing in the approximation of a spherical wavefront of CID propagation.

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“…This causes steepening of the initial part of the wave, and the whole waveform approaches that of a shock wave (Naugolnykh and Ostrovsky, 1998, section 3.5). Magnetic field may weaken these processes above ∼120 km (Ostrovsky, 2008), and the slope of the wave front decreases and the wavelength extends up to tens of hundreds of kilometers at the height of the F-layer. Atmospheric viscosity also changes the waveform by isolating the wave with frequencies within a window of 3-10 mHz (Blanc, 1985).…”

Section: Discussionmentioning

confidence: 99%

Dependence of waveform of near-field coseismic ionospheric disturbances on focal mechanisms

Astafyeva

Heki

2009

Earth Planet Sp

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Using Total Electron Content (TEC) measurements with Global Positioning System we studied ionospheric responses to three large earthquakes that occurred in the Kuril Arc on 04 October 1994, 15 November 2006, and 13 January 2007. These earthquakes have different focal mechanisms, i.e. high-angle reverse, low-angle reverse, and normal faulting, respectively. TEC responses to the 2006 and 2007 events initiated with positive and negative changes, respectively. On the other hand, the initial TEC changes in the 1994 earthquake showed both positive and negative polarities depending on the azimuth around the focal area. Such a variety may reflect differences in coseismic vertical crustal displacements, which are dominated by uplift and subsidence in the 2006 and 2007 events, respectively, but included both in the 1994 event.

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Ionospheric effects of ground motion: The roles of magnetic field and nonlinearity

Cited by 9 publications

References 21 publications

Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012

Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012

Two‐mode long‐distance propagation of coseismic ionosphere disturbances

Dependence of waveform of near-field coseismic ionospheric disturbances on focal mechanisms

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