ИСТИНА

We present an analysis of the behavior of the solar wind velocity in the vicinity of strong current sheets (CSs) at the Earth orbit. 3-second resolution data from the Wind spacecraft located at 1 AU are used. The study is conducted for the years of maximum and minimum of solar activity of 23 and 24 solar cycles. CSs are identified by the method of automatic recognition of this type of discontinuities [1]. The statistics include more than 300 000 CS crossings. Histograms of the solar wind velocity components distribution outside and at CSs are analyzed. There is a significant shift in the histogram of the horizontal Y component (GSE) of the solar wind speed towards high values near CSs, especially pronounced in the maximum of solar activity. In two subsequent solar cycles, the direction of particle motion with high velocities along Y is reversed. A detailed analysis shows that the effect in the Y component of the solar wind speed corresponds to the formation of a narrow plasma flow in the vicinity of CSs. The obtained results are compared with theoretical predictions of the kinetic model describing the behavior of the proton motion in the vicinity of CSs [2], [3]. The change in the solar wind flow in Y direction is a consequence of the effect of quasi-adiabatic particle motion in CSs with the presence of a magnetic field component perpendicular to the CS plane. Plasma flows propagating in the X direction from the Sun along a strong CS unfold in the perpendicular direction and flow in the azimuthal (Y) direction, providing an increase in the observed hydrodynamic velocity. The direction of the shift in the histogram depends on the polarity of the solar magnetic field. Therefore, the impact of kinetic processes at CSs on the movement of solar wind particles is manifested at MHD scales in the nearest vicinity of strong CSs. [1] Khabarova O., Sagitov T., Kislov R., Li G. Automated Identification of Current Sheets—A New Tool to Study Turbulence and Intermittency in the Solar Wind // Journal of Geophysical Research: Space Physics., 2021, v. 126, doi: 10.1029/2020JA029099.