Ionospheric irregularities in the E-region

On the possible detection of tsunamis by a monitoring of the ionosphere

“…Their potential role can be assessed only empirically, and this is best done at the sites where actual detection is contemplated. It is well known, however, that there are often fluctuations in the phase height of isopleths of electron concentration that exceed the 100-m amplitude we have estimated here for the tsunami signature [e.g., Vincent, 1972], and consequently, we must anticipate adverse conditions for signal detection much of the time.…”

“…We have found the dissipative attenuation.•to be negligibly small in the first case and to reduce the amplitude in the second case by a factor of about 10. Both in the E layer and in the F layer, then, we anticipate vertical moverbents of the isopleths with amplitudes of the order of + 100 m. Such amplitudes are comparable to the wavelengths of the radio waves that would be employed to monitor the isopleths and so are readily detectable in a phase height system of observation [e•g,, Vincent, 1972]. Some degradation of amplitude may occur if the height of observation is nearly midway between neighboring z' = ' levels, but by an amount that appears unlikely to invalidate this conclusion..The monitoring could in any event be conducted at two or more levels within the ionosphere, separated appropriately in height to ensure that at least one of them was located favorably for detection.…”

Observations of ionospheric disturbances following a 5‐kt chemical explosion: 1. Persistent oscillation in the lower thermosphere after shock passage

“…Eventually, data from a large filled-aperture array [Felgate and Golley, 1971-1 provided rather compelling evidence for the ray interference model. Additional results by Pfister [1971] and Vincent [1969Vincent [ , 1972 strengthened the case for interference between rays from long-scale (tens of kilometers) ionospheric structures. These developments led to a reasonable consensus that although partial reflection "drifts" are likely to be caused by wind-borne irregularities, total reflection "drifts" are caused by both irregularities and coherent wavelike structures.…”

“…During the exercise of the complex analysis technique in section 3 (below), we will be careful to limit the analysis to a time period during The presence of fine spatial scales on the ground (see (4)), for sufficiently large modulation index, enables compact arrays to track the motion even of ionospheric waves whose scale greatly exceeds the array dimension (namely by a factor of ,•b0). Moreover, these fine spatial scales are produced by the Doppler sidebands; one is not relying on amplitude ("fading") scales, which become fully developed only in the far field or in the special case of focusing (see discussion and references by Vincent [1972]).…”

“…This gives an amplitude of 6z _• 0.097 km. (Refractive effects may cause this to be an underestimate by up to 20%; see the discussion byVincent [1972]). The corresponding peak vertical velocity of the reflection surface would thus be v-• 1.6 m/s.…”