Articles | Volume 16, issue 6
Nonlin. Processes Geophys., 16, 691–698, 2009
https://doi.org/10.5194/npg-16-691-2009
Nonlin. Processes Geophys., 16, 691–698, 2009
https://doi.org/10.5194/npg-16-691-2009

  15 Dec 2009

15 Dec 2009

Variability of magnetic field spectra in the Earth's magnetotail

A. A. Petrukovich and D. V. Malakhov A. A. Petrukovich and D. V. Malakhov
  • Space Research Institute, 84/32 Profsoyuznaya st., Moscow, 117997, Russia
  • Moscow Institute of Physics and Technology, Moscow, Russia

Abstract. 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 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.