Аннотация:Fractal properties of the long-period irregular np pulsations at the initial
phase of 14 magnetic storms were studied based on the data of magnetic observations at
the high-latitude Mirny observatory (φ = −77.2◦, λ = 122.6◦). The fractal dimensionality
(D) of the np pulsations was determined using spectral analysis and the “critical exponents” method. An inverse correlation between D and the Dst variations is found. It is
demonstrated that the fractal dimensionality of the np pulsations and, respectively, the
pulsation field structure depend on the duration of the initial phase of the storm and the
Dst-variation value. Possible influence of the intensity and action time of the DCF fields
on the regime character (chaotic or regular) of the long-period irregular np pulsations
at the initial phase of a storm is discussed. It is suggested that the np-pulsation fractal
dimensionality may serve as an indicator of the magnetosphere disturbance degree.