Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

L. Rakhmanova et al. Fig. 3 presents dependencies of the flatness on the time scale l /т for two cases when long enough time intervals were available - December 19,2015 (panel a) and March 15, 2013 (panel b). For both o f the cases at scales ~100 sec flatness is close to 3, that is, PDF is close to Gaussian. At panel a flatness increases significantly with decreasing of the scale (or increasing of l /т) upstream as well as downstream the IP shock. Thus, in this case PDF is not Gaussian and have heavier wings. In this case high level of the ion flow intermittency occur on both sides o f the shock front. At panel b the deviation of flatness from 3 is negligible for each scale upstream and downstream the IP shock. That is, low intermittent flow occur in this case before and after registration o f the shock front. Thus, IP shocks do not change intermittency level in the magnetosheath. Figure 3. Flatness versus time scale upstream (black line) and downstream (grey line) the interplanetary shock on (a) - December 19, 2015; and (b) - March 15, 2013. Dashed lines mark flatness value 3 inherent for gaussian probability distribution function. 3. Summary and discussion Magnetosheath plasma turbulence plays a crucial role in the energy transport and processes of plasma heating in the near-Earth space. However, kinetic scale part of the turbulent cascade in the magnetosheath is not studied completely yet. In the present study large scale structures (such as interplanetary shocks) influence on the plasma turbulence in the magnetosheath is considered. Four cases of IP shocks registration are analyzed in the paper. The results can be summarized as follows: - Power spectral density of the kinetic-scale ion flux fluctuations increases by one order o f amplitude downstream the IP shock front for tree of four cases. This result is consistent with the results of (Pitna et al., 2016) obtained in the solar wind. In one case PSD increases by the factor o f250. This case refers to the most slow IP shock with the highest 0 bnip angle. - In half of the cases spectra slope o f the kinetic part of the spectra do not change with IP shock propagation. However, in other cases steepening as well as flattening of the spectrum occur. Due to the absence o f statistics no conclusions can be done concerning proportionality between spectral slopes upstream and downstream IP shocks. - Exponential cutoff of the kinetic part of the spectra does not observed in the magnetosheath downstream the IP shock while this is the case for half of the events in the solar wind (Pitna et al., 2016). We suggest that exponential cutoff of the spectra is due to the high solar wind velocities downstream the IP shock, which do not occur in the magnetosheath. - According to case study, IP shocks do not change a level o f the ion flow intermittency. This fact was shown both for cases with high and low intermittency level in the upstream plasma flow in the magnetosheath. Presented results point out that IP shocks seem not to change the features of the turbulent cascade and properties of the probability distribution function in the magnetosheath plasma. Acknow ledgments. The reported study was funded by RFBR according to the research projects No. 16-32-00818, 16-02-00669 and 16-02-00125. References Alexandrova, О., C. Lacombe, A. Mangeney (2008), Spectra and anisotropy o f magnetic fluctuations in the Earth’s magnetosheath: Cluster observations, Лии. Geophys. 26, 3585-3596. doi:10.5194/angeo-26-3585 2008. Bruno R., V. Carbone (2013), The solar wind as a turbulence laboratory, Living Rev. Sol. Phys. V. 10 doi:10.12942/lrsp-2013-2. 2013. Frisch, U. (1995), Turbulence. Cambridge University Press. 84