Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/angeo-2018-50
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Regular paper
04 Jun 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Annales Geophysicae (ANGEO).
Turbulent Processes in the Earth's Magnetotail: Spectral and Statistical Research
Liudmyla Kozak1,2, Bohdan Petrenko1, Anthony T. Y. Lui3, Elena Kronberg4,5, Elena Grigorenko6, and Andrew Prokhorenkov1 1Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
2Space Research Institute of the National Academy of Sciences of Ukraine and State Space Agency of Ukraine, Kyiv, Ukraine
3Johns Hopkins University Applied Physics Laboratory, Laurel MD, USA
4Max Planck Institute for Solar System Research, Göttingen, Germany
5Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, Munich, Germany
6Space Research Institute, RAS, Russia
Abstract. We use the ferroprobe measurements from four spacecraft of Cluster-2 mission (3 events from 2005 to 2015) for the analysis of turbulent processes in the Earth's magnetotail. For this study we conduct the spectral, wavelet and statistical analysis. In the framework of statistical examination, we determine the kurtosis for selected events and conduct extended self-similarity evaluation (analysis of distribution function moments of magnetic field fluctuations on different scales). We compare high order structure function of magnetic fluctuations during dipolarization with isotropic Kolmogorov and three-dimensional log-Poisson model with She-Leveque parameters. We obtain power law scaling of the generalized diffusion coefficient (the power index that varies within the range of 0.2–0.7). The obtained results show the presence of super-diffusion processes. We find the significant difference of the spectral indices for the intervals before and during the dipolarization. Before dipolarization the spectral index lies in the range from −1.68 ± 0.05 to −2.08 ± 0.05 (~ 5/3 according to the Kolmogorov model). During dipolarization the type of turbulent motion changes: on large time-scales the turbulent flow is close to the homogeneous models of Kolmogorov and Iroshnikov-Kraichnan (the spectral index lies in the range −2.20/−1.53, and at smaller time scales the spectral index is −2.89/−2.35 (the Hall-MHD model). The kink frequency is less or close to the average value of the proton gyrofrequency.

The wavelet analysis shows the presence of both direct and inverse cascade processes, which indicates the possibility of self-organization processes, as well as the presence of Pc pulsations.

Citation: Kozak, L., Petrenko, B., Lui, A. T. Y., Kronberg, E., Grigorenko, E., and Prokhorenkov, A.: Turbulent Processes in the Earth's Magnetotail: Spectral and Statistical Research, Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2018-50, in review, 2018.
Liudmyla Kozak et al.
Liudmyla Kozak et al.
Liudmyla Kozak et al.

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Short summary
We analyzed the turbulent processes in the Earth's magnetotail in the regions of magnetic filed dipolarization and compared them with known models. We used spectral and statistical methods for analysis measurements from Cluster-II mission. We have obtained a significant difference for turbulent processes depending on observed scales. Our results can be interesting for classification of the turbulent processes in both hydrodynamics and magnetohydrodynamics environments.
We analyzed the turbulent processes in the Earth's magnetotail in the regions of magnetic filed...
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