Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 16 6 2009 10.5194/npg-16-691-2009 http://www.nonlin-processes-geophys.net/16/691/2009/ http://www.nonlin-processes-geophys.net/16/691/2009/npg-16-691-2009.html http://www.nonlin-processes-geophys.net/16/691/2009/npg-16-691-2009.pdf 691 698 2009-12-15 Variability of magnetic field spectra in the Earth's magnetotail A. A. Petrukovich apetruko@iki.rssi.ru D. V. Malakhov Space Research Institute, 84/32 Profsoyuznaya st., Moscow, 117997, Russia Moscow Institute of Physics and Technology, Moscow, Russia 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. 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