On the character of cosmic ray variations at f>2x10^-5 Hz

Abstract. We examine the time series of cosmic ray (CR) intensity recorded by two neutron monitors (NMs) at medium latitudes for scaling properties on time scales shorter than the diurnal variation. Scaling of the data with 10 sec as well as I min resolution is shown to be complicated, indicating that there is probably not a unique process governing the CR fluctuations in the whole interval studied. For T < 20 min the general characteristics are similar to those of white noise. Above 40-60 min the scaling characteristics are dependent on the level of interplanetary disturbance. This is consistent with the concept of scattering CRs by inhomogeneities of the interplanetary magnetic field (IMF). With increasing interplanetary turbulence the dimensionality of the CR time series decreases. The region of stable scaling is, however, narrow, only up to 6 hours. Multifractality signatures in the region 1-6 hours are similar to those in the IMF, however the deviations from monofractality are relatively small.