SCALING LAWS FROM GEOMAGNETIC TIME-SERIES

The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting n th order structure functions against the fourth order structure functi on we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind , however, for higher frequencies (f > 1/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling law s in ''geomagnetic'' turbulence. However, we suggest to use higher ord er moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data.