TIME INTERMITTENCY AND SPECTRAL FEATURES OF THE GEOMAGNETIC FIELD

Abstract

In the field of geomagnetism a number of studies have been devoted to the investigation of turbulence and in- termittency in the outer core fluid motions. Here, in order to obtain information on such phenomena we study the time spectral and self-similarity features of the main geomagnetic field fluctuations as measured on the Earth's surface. The existence of a power law spectrum, characterised by an exponent α ≈−11/3, and an anom- alous scaling of q-th order structure functions on time scales longer than 5 years, suggests the occurrence of in- termittent turbulence rather than classical Kolmogorov turbulence in the fluid core motions. These results are briefly discussed in connection with the existence of a strong magnetic field and drift-wave turbulence.