Turbulent spreading of artificial periodic inhomogeneities in the lower ionosphere

Gershman, B. N.; Ryzhov, Yu. A.

doi:10.1007/bf01033903

Cited by 2 publications

(1 citation statement)

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“…As might be expected, the amplitude of the scattering decreases in the presence of turbulence. Gershman and Ryzhov (1983) considered the effect of only turbulent mixing on the decay of API in the 70-90-km height range and give an expression for the relaxation time in terms of the mean-square velocity of turbulent motion and the scale of inhomogeneity. Grigor'ev et al (1990) showed that for typical gravity waves the characteristic relaxation time of the scattered signal is reduced to 1-10 s instead of the much longer times characteristic of ambipolar diffusion in the E region.…”

Section: Previous Workmentioning

confidence: 99%

Artificial periodic irregularities in the auroral ionosphere

Rietveld

Turunen²,

Matveinen³

et al. 1996

Ann. Geophys.

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Abstract. Artificial periodic irregularities (API) are produced in the ionospheric plasma by a powerful standing electromagnetic wave reflected off the F region. The resulting electron-density irregularities can scatter other high-frequency waves if the Bragg scattering condition is met. Such measurements have been performed at midlatitudes for two decades and have been developed into a useful ionospheric diagnostic technique. We report here the first measurements from a high-latitude station, using the EISCAT heating facility near Tromsø, Norway. Both F-region and lower-altitude ionospheric echoes have been obtained, but the bulk of the data has been in the E and D regions with echoes extending down to 52-km altitude. Examples of API are shown, mainly from the D region, together with simultaneous VHF incoherent-scatter-radar (ISR) data. Vertical velocities derived from the rate of phase change during the irregularity decay are shown and compared with velocities derived from the ISR. Some of the API-derived velocities in the 75-115-km height range appear consistent with vertical neutral winds as shown by their magnitudes and by evidence of gravity waves, while other data in the 50-70-km range show an unrealistically large bias. For a comparison with ISR data it has proved difficult to get good quality data sets overlapping in height and time. The initial comparisons show some agreement, but discrepancies of several metres per second do not yet allow us to conclude that the two techniques are measuring the same quantity. The irregularity decay time-constants between about 53 and 70 km are compared with the results of an advanced ion-chemistry model, and height profiles of recorded signal power are compared with model estimates in the same altitude range. The calculated amplitude shows good agreement with the data in that the maximum occurs at about the same height as that of the measured amplitude. The calculated time-constant agrees very well with the data below 60 km but is larger above 60 km by a factor of up to 2 at 64 km. The comparisonsCorrespondence to: M. T. Rietveld with the model are considered to be a good basis for more refined comparisons.

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Section: Previous Workmentioning

confidence: 99%