Low-latitude ionospheric turbulence observed by Aureol-3 satellite

Abstract

Abstract. Using PSD (Power Spectral Density) data on electron density and electric field variations observed on board Aureol-3 satellite at low-to-mid-latitude ionosphere we analyze a scale distribution of the ionospheric turbulence in a form k −α , where k is the wave number and α is the spectral index. At first, high-resolution data in the near-equator region for several orbits have been processed. In this case the frequency range is from 6 Hz to 100 Hz (corresponding spatial scales from 80 m to 1.3 km), each power spectrum obeys a single power law fairly well, and the mean spectral indices are rather stable with α N =2.2±0.3 and α E =1.8±0.2, for the density and electric field, respectively. Then we produce a statistical study of 96 electric field bursts in the frequency range 10-100 Hz from low-time resolution data (filter bank envelope). These bursts concentrate on the side of the Equatorial Anomaly crest (geomagnetic latitude 30-40 • ). Spectral indices of the bursts vary in the interval α E =2.0-2.5 but are fairly stable in seasons and local times. The electric field power of the burst has rather a large variability but has a relative increase in mean values for the summer and winter, as well as the daytime. The effect of major seismic activities toward the ionospheric turbulence is not conclusive either for the refractive index or for the electric field power. However, the mean value for the electric field power of bursts during seismic periods is larger than that for non seismic periods, and the statistical difference of the mean values is rather significant.

Ionospheric perturbations observed by the low altitude satellite DEMETER and possible relation with seismicity

“…These enhancements are symmetrical around the magnetic equator. As was reported in the previous works by Hobara et al (2005b), the observed electric field fluctuations exhibit nearly an identical characteristic as upper ionospheric perturbations and are located on the side of the EA crest. The electric field enhancement near EA is mostly identified during daytime orbits in DEMETER.…”

“…In this paper we perform the similar data analysis as was reported by Hobara et al (2005b) by using the ELF electric field data from Aureol 3 satellite. They found that mean value of the electric field power during the seismic period is much higher than that for no seismic period.…”

“…Short-scale (0.1 m to 10 m) density perturbation is identified by the electric field measurement in the VLF frequency range by IK-24 satellite , while the transitional scale (10-100m) are statistically studied by the ELF electric field fluctuations by Aureol 3 satellite and the enhancements of the field intensity were found around the major seismic activities (Hobara et al, 2005b). Large scale electron density perturbations are directly measured by Cosmos-900 satellite and the decrease of the electron density was found in association with seismic activity (Molchanov et al, 2004).…”

Fractal analysis of subionospheric LF propagation data and consideration of the lithosphere-atmosphere-ionosphere coupling

“…The similar kind of ideas was applied to the in-situ data of electron density and electric field observed by different satellites traversing in the upper ionosphere (Cosmos-900 and Aureol-3) Hobara et al, 2005). That is, the fluctuations in the plasma density and electric field in the ionosphere have been investigated in terms of the fractal exponent.…”

Decrease of VLF transmitter signal and Chorus-whistler waves before l'Aquila earthquake occurrence

“…The penetration of AGW waves into the ionosphere leads to modification of the natural (background) ionospheric turbulence Hobara et al, 2005). In this model the ground-based VLF station signals is scattered in the ionospheric turbulence region above the earthquake preparatory zone.…”