Intermittency in the auroral absorption fluctuations as manifistation of magnetospheric turbulence

Statistical properties of the auroral absorption fluctuations measured by the broad-beam riometer deployed at the South Pole Station were studied for different for magnetic local times (MLT). Analysis of the Probability Density Functions (PDFs) of these fluctuations has shown that these exhibit non-Gaussian properties on small time scales while large scale features are uncorrelated. Here we fit of the PDFs by a functional form proposed by Castaing et al. [1990] to describe intermittency phenomena in ordinary turbulent fluid flows. This fit allows us to calculate a parameter depending on the scale, which represents the width of the log-normal distribution of the variances of the gaussians. We also used the finite size scaling technique to explore the scaling of the auroral absorption independently on their functional form. It was found that the departure of PDF's from the Gaussians is strongly dependent of the MLT, and the behavior of the auroral absorption fluctuations is more intermittent in the night sector of MLT with the maximum close to 22 hours. The results obtained showed that the acceleration of precipitating particles is intermittent, especially nearly the substorm eye, where the level of turbulence is increased.