ИСТИНА

We use the magnetohydrodynamic (MHD) classification to make an analysis of frequency of occurrence of solar wind types. This classification is based on four parameters: proton density n, speed V, temperature T and dimensionless plasma parameter "beta" for protons. The statistical analysis of the main MHD parameters is done in [1]. In the space of these parameters the boundaries for fast (f) and slow (s), hot (h) and cold (c), dense (d) and rarefied (r), magnetized (m) and nonmagnetized (n) wind are set. In total, we obtain 2^4=16 solar wind types: fhdm, fhdn, fhrm, etc. We also add a zero type, which corresponds to the solar wind streams, where value of at least one parameter is close to the statistical average. For our work we use the 1-minute OMNIWeb data [2] for the period from 1996 to 2017 (23rd and 24th solar cycles). The example of the alternation of wind types (magnetized subset) for 2016–2017 is shown in Fig. 1. Table 1: The frequency of occurrence of magnetized types (separately and in total), nonmagnetized types and the zero type in Carrington rotations 2173–2198 We also tried to find a correspondence of common and rare types with their sources such as coronal holes, CME, etc. Comparison with previous classifications ([3–5] for example) are made and discussed. References: [1] Veselovsky I.S., Dmitriev A.V., Suvorova A.V. Algebra and statistics of the solar wind // Cosmic Research. 2010. V. 48. No. 2. P. 113–128. [2] https://omniweb.gsfc.nasa.gov [3] Richardson I.G., Cane H.V., Cliver E.W. Sources of geomagnetic activity during nearly three solar cycles (1972–2000) // J. Geophys. Res. 2002. V. 107. No. A8. [4] Yermolaev Yu.I., Nikolaeva N.S., Lodkina I.G., Yermolaev M.Yu. Catalog of large-scale solar wind phenomena during 1976–2000 // Cosmic Research. 2009. V. 47. No. 2. P. 81–94. [5] Xu, F., Borovsky J.E. A new four-plasma categorization scheme for the solar wind // J. Geophys. Res. Space Physics. 2015. V. 120. No. 1. P. 70–100.