Narrow Results

An algorithm for the solution of the inverse problem of vertical ionosphere sounding and a mathematical model of noise filtering are presented. An automated system for processing and analysis of spectrograms of vertical ionosphere sounding based on our algorithm is described. It is shown that the algorithm we suggest has a rather high efficiency. This is supported by the data obtained at the ionospheric stations of the so-called “AIS-M” type.

By using the PIC simulation method and theoretical investigation from both the magnetohydrodynamic equations and the Vlasov equation of the dusty plasma produced by the relative streaming of the dust fluid and the background ionospheric plasma, we investigate the instability of the waves excited by this kind of the dust beam in the ionosphere. It is found that the waves are stable in both the electron and ion vibration time scales, while they are unstable in the dust grain vibration time scale. It is inferred that the wave is the high hybrid wave in the electron vibration time scale. The dispersion relations of the perturbed waves in both the electron vibration and ion vibration time scales are obtained. As the time increases until it arrives at the dust grain vibration time scale, the instability appears for the perturbed wave. Such instabilities may drive plasma irregularities that could affect radar backscatter from the clouds, when the wave satisfies the Bragg condition for backscatter. By using the dispersion relation of waves in both electron vibration and ion vibration time scales, we can infer what kind of radar backscatter can be possibly affected by the instability of the perturbed waves.

During the Cassini Mission, when the spacecraft crossed the D ring, it detected a magnetic perturbation of 15-25 nT. This doesn’t arise intrinsically but induced by external currents. Such an unexpected current system can be explained in terms of the dynamo mechanism originated from the difference in the zonal wind speed at the footpoints of the planetary magnetic field lines. In Khurana et al., 2018, the total current is accordingly estimated to be as large as ∼7 MA. In this study, we apply the same pattern of the zonal wind-driven currents at the other three outer planets, and find out that the maxima of Jupiter, Uranus and Neptune are 0.20 MA, 0.44 MA and 0.63 MA.

Here, we first analyze data from two GPS stations operating in Tashkent and Kitab and new Very Low Frequency (VLF) radio receiver operating in Tashkent for the possible earthquake ionospheric precursors. We find anomalous Total Electron Content (TEC) precursor signals and significant correlation in time between the TEC anomalies and the occurrence of the earthquake in Tashkent on August 22, 2008, M = 4.4. The obtained results have revealed a fine agreement with the TEC anomalies observed during the strong earthquake in Tashkent and we demonstrate the capabilities of the GPS technique to detect ionospheric perturbations caused by the local earthquakes. TEC decrease during the solar eclipse on August 1, 2008 is also obtained from the data at GPS stations in Tashkent and Kitab. We used tweek radio atmospherics (originating from lightning discharges) to estimate electron densities in the D-layer of ionosphere. The propagation characteristics of tweek atmospherics observed at the Tashkent station have been studied near the mode cut-off frequencies. It is shown that the height of the Earth-Ionosphere Wave Guide (EIWG) varies from 84 km to 91 km and nighttime electron density varies from 25 el/cm³ to 27 el/cm³. We have also studied VLF amplitude anomalies related to the earthquakes occurring on the path from the VLF transmitters to the Tashkent station. For analyzing narrowband data we have used the Nighttime Fluctuation method paying attention to the data obtained during the local nighttime (18:00 LT- 06:00 LT). The deathlines for rotating as well as oscillating magnetars are obtained for the different modes of oscillations and it is shown that the oscillations increase the region in the (P is the period) diagram of the magnetars which is allowed for the radio emission.