Variability of magnetic field spectra in the Earth's magnetotail

A. A. Petrukovich, D. V. Malakhov
2009 Nonlinear Processes in Geophysics  
We investigate the variability of magnetic fluctuation spectra below 1 Hz in the Earth's plasma sheet using specially selected long observation intervals by Geotail spacecraft. The spectra can be generally described by a negative power law with two kinks. The range between kinks ∼0.02-0.2 Hz has the most stable power law index ∼2.4-2.6. Indices at the lower and the higher frequencies are more variable and generally increase with power of fluctuations. In the sub-second range fluctuations are
more » ... fluctuations are strongly localized and indices are closer to 3. At the lower-frequency end indices are about 1.5. The lower kink is usually well defined on average spectra and its frequency tends to increase with activity. Combination of spectrum index α and fractal dimension δ is expected to follow the Berry relation α +2δ = 5, but actually is ∼5.5.
doi:10.5194/npg-16-691-2009 fatcat:xrdalspojzh4bdve7i6hsx6mru