Abstract and keywords
Abstract (English):
During large-scale solar wind disturbances, variations in galactic cosmic rays with periods from several minutes to 2–3 hours, which are called cosmic ray fluctuations in the scientific literature, often occur. Such fluctuations are not observed in the absence of disturbances. Since cosmic rays are charged particles, their modulation in the heliosphere occurs mainly under the influence of the interplanetary magnetic field, or rather its turbulent part — MHD waves. In order to adequately describe the relationship between their fluctuation spectra, it is necessary to be able to isolate a certain type of MHD waves from direct measurements of the interplanetary medium parameters. In this paper, we consider some methods for determining the contribution of three solar wind MHD turbulence branches, namely, Alfvén, fast, and slow magnetosonic waves corresponding to the turbulence spectrum inertial region frequencies 10⁻⁴<ν<10⁻¹ Hz, at which cosmic ray fluctuations are observed, to the observed power spectra of interplanetary magnetic field modulus fluctuations. To do this, we apply the methods of spectral and polarization analysis. In the absence of measurement data on SW parameters, to identify the type of MHD turbulence we use the known wave polarization properties that Alfvén and magnetosonic waves are polarized in different planes relative to the plane containing the average IMF vector and wave vector. Our results show that with the correct determination of the spectra of three MHD wave types, their sum, within the limits of errors, agrees well with the observed spectra of the interplanetary magnetic field modulus, and a small difference can be attributed to static inhomogeneities and oscillations frozen into plasma, as well as to various discontinuities that are always inevitably present in the solar wind.

cosmic rays, interplanetary magnetic field, solar wind, MHD waves
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1. Berezhko E.G., Starodubtsev S.A. Nature of the dynamics of the cosmic-ray fluctuation spectrum. Izvestiya Akademii Nauk SSSR. Seriya Fizicheskaya [Bulletin of the Academy of Sciences of USSR. Ser. Physics]. 1988, vol. 52, pp. 2361–2363. (In Russian).

2. Jenkins G.M., Watts D.G. Spektralnyi analiz i ego prilozheniya [Spectral Analysis and Its Applications]. Moscow, Mir Publ., 1971, iss. 1, 317 p. (In Russian). (English edition: Jenkins G.M., Watts D.G. Spectral Analysis and Its Applications. San Francisco, Cambridge, London, Amsterdam, Holden-Day, 1968, 525 p.)

3. Kanacevich E.R. Analiz vremennykh posledovatelnostei v geofizike [Time Sequence Analysis in Geophysics]. Moscow, Nedra Publ., 1985, 401 p. (In Russian).

4. Kovalenko V.A. Solnechnyi veter [Solar Wind]. Moscow, Nauka Publ., 1983, 283 p. (In Russian).

5. Kulikovskii A.G., Liubimov G.A. Magnitnaya gidrodinamika [Magnetohydrodynamics]. Moscow, Izdatel’stvo Fiz.-Mat. Literatury, 1962, 246 p. (In Russian).

6. Luttrell A.H., Richter A.K. A study of MHD fluctuations upstream and downstream of quasi-parallel interplanetary shocks. J. Geophys. Res. 1987, vol. 92, pp. 224–2252.

7. Neugebauer M., Wu C.S., Huba J.D. Plasma fluctuations in the solar wind. J. Geophys. Res. 1978, vol. 83, pp. 1027–1034.

8. Otnes R., Enochson L. Prikladnoi analiz vremennykh ryadov. Osnovnye metody [Applied Time Series Analysis. Basic Techniques.] Moscow, Mir Publ., 1982, 430 p. (In Russian). (English edition: Otnes R., Enochson L. Applied Time Series Analysis. Vol. 1. Basic Techniques. New York, Wiley Publ., 1978, 449 p.).

9. Owens A.J. Cosmic-ray scintillations. 2. General theory of interplanetary scintillations. J. Geophys. Res. 1974, vol. 79. pp. 895–906.

10. Starodubtsev S.A, Transkii I.A., Verigin M.I., Kotova G.A. Intensity fluctuations of cosmic rays and of the interplanetary magnetic field in the region of interaction of solar-wind streams with different velocities. Geomagnetism and Aeronomy. 1996, vol. 36, pp. 241–244.

11. Toptygin I.N. Kosmicheskie luchi v mezhplanetnykh magnitnykh polyakh [Cosmic Rays in Interplanetary Magnetic Fields]. Moscow, Nauka Publ., 1983, 304 p. (In Russian).

12. Transkii I.A., Starodubtsev S.A. Polarization parameters of large-scale turbulence of the solar wind and fluctuations of the cosmic ray intensity. Geomagnetism and Aeronomy. 1991, vol. 31, pp. 19–23.

13. URL: https://ysn.ru/ipm (accessed February 22, 2023).

14. URL: https://omniweb.gsfc.nasa.gov/form/sc_merge_min1.html (accessed February 22, 2023).

15. URL: https://lweb.cfa.harvard.edu/shocks (accessed February 22, 2023).

16. URL: https://izw1.caltech.edu/ACE/ASC/index.html (accessed February 22, 2023).

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