Angular Dependencies of the Ionospheric Scintillation Parameters Based on Observations of the Cosmic Radio Sources in the Decameter Radio Wave Range

Passing through the Earth's ionosphere the radio wave from cosmic source crosses the layer with electron concentration irregularities which cause random phase fluctuations of the radio wave that leads to intensity fluctuations.Due to movement of the irregularities along the line of sight the intensity fluctuations at the receiving point, are observed as the temporary fluctuations of radio signal known as ionospheric scintillations.This effect is most pronounced in decameter radio wave range.Its intensity is determined by the heterogeneous structure of ionosphere, and, among other things, depends on the geometry of the radio signal propagation which is associated with the manifestations of the angular dependencies of the ionospheric scintillation parameters.Such dependencies reflect the heterogeneous structure of ionosphere and can serve as a research tool.According to long-term observations of the power cosmic radio sources in the decameter radio wave range the estimations of the ionospheric scintillation parametersindex, period and spectral index, were obtained.The dependencies of these values on the zenith angle and on the angle between source direction and geomagnetic field line were analyzed.It is shown, that the scintillation index and period are related to each other in inverse proportion and show the dependencies on angle between source direction and geomagnetic field line.At the same time, the spectral index demonstrates the well expressed dependence on the radio source zenith angle.