Plasma density-electric field turbulence in the low-latitude ionosphere from the observation on satellites; possible connection with seismicity

Abstract

Based on plasma density data from the Cosmos-900 satellite we have analyzed the spatial distribution of the ionospheric turbulence in a form k − b , where k is wave number and b is the fractal index. In this case spatial scales (∼ k −1) are ranging from 15 to 300 km at the satellite height h=450–500 km. Depending on season, local time and seismic activity the index 〈 b〉 varies in the interval 1.3–1.9. Then we have considered the slope of the spatial distribution for electric field turbulence observed on board the IK-24 satellite ( h=500–700 km, scales of several meters). Supposing a simple connection between the power spectrum density of the plasma and the electric field we find 〈 b〉=1.2–1.7. Remembering that from observation on board the Aureol-3 satellite ([Radio Science 20 (1985) 755]; h=500–700 km, scales 10–300 m) b=1.7–1.9 both for the plasma density and electric field variations, we conclude that the ionospheric turbulence is a unique process in a large interval of scales from hundreds km to several meters and the b-dependence is similar to the classic Kolmogorov's turbulence b=5/3. Intensification of the turbulence near the magnetic equator is definitely connected with the presence of the equatorial density anomaly (EA) but existence of the regular moderate level aside of EA and at the mid-latitude ionosphere invokes a possibility of another energy source, probably atmospheric gravity waves.