ИСТИНА

We present and discuss the magnetohydrodynamic (MHD) types of the solar wind. The analysis of frequency of occurrence of these types near the Earth’s orbit during the past two solar cycles is performed. Our classification is based on four main MHD parameters: proton density n, speed V, temperature T and dimensionless plasma beta parameter for protons. In the space of these four 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 42=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 mean value. All these types occur due to different solar activity phenomena and appear with various frequency at different phases of the solar cycle. We considered 23rd and 24th solar cycles and tried to find a correspondence of common and rare types with their sources on the Sun. The 1-minute OMNIWeb data [1] for the period from 1996 to 2017 were used. An example of the alternation of wind types (magnetized subset) for 2016–2017 is shown in Fig. 1. Figure 1: Magnetized types of solar wind in Carrington rotations 2173–2198: fhdm – red, fhrm – yellow, fcdm – blue, fcrm – cyan, shdm – purple, shrm – pink, scdm – dark-green, scrm – light-green. Correspondence with previous more intuitive and problem-oriented classifications are established. One of our main physical findings indicates that there is only a limited sense to search localized coronal sources of the solar wind with average properties. It is due to nonlocality of the phenomenon. The whole corona is responsible for the intermittent production of the solar wind with average properties. References [1] https://omniweb.gsfc.nasa.gov