4. Discussion of the Solar Cycle in the Heliosphere and the Main Phases for the GCR Intensity Modulation

[14]  In the heliosphere there are also phenomena which are closely related to T branch of solar activity as characterized by their strength (not polarity) and not dependent on the phase of the magnetic cycle: the change of the strength of the regular and fluctuating components of the interplanetary magnetic field, the change of the distribution of the solar wind parameters etc. Similarly, there is a heliospheric phenomenon, which is related to the development of the P activity on the Sun: the formation and change of the dipole-like polarity distribution of the interplanetary magnetic field with the global current sheet dividing two magnetic hemispheres. However, in the course of the transition from the photosphere to the inner heliosphere the accelerating and expanding solar wind is influenced by both T and P branches of solar activity. So the resulting heliospheric characteristics could not be assigned exclusively to T or P branches. Rather, they could be classified as changing with the 11-year or 22-year periods (11-year and 22-year branches), both bringing the imprints of T and P types of solar phenomena.

[15]  The GCR intensity is governed by the heliospheric factors of both 11-year and 22-year branches. Some notions about the sought for SC main phase classification for the GCR modulation are quite obvious. For example, the time boundaries of the phases should shift forward as one moves from the Sun to the solar wind termination shock and then gradually wash away by the periphery of the heliosphere due to the superposition of many previous cycles there.

[16]  However, first we should decide what physical meaning we ascribe, e.g., to the extreme SC phases for the GCR intensity modulation. There is an important difference between the VKO classification for the solar activity itself and the sought for SC phase classification for such test particles as the GCRs. On the Sun even in the extreme phases both T and P branches are important. Contrary, for the GCR modulation the extreme phases in principle could be characterized by the small influence on the GCR intensity of one of the modulating factors. So our initial assumption is that during the SC minimum phase the GCR behavior is mainly determined by the 22-year branch of the heliospheric activity (the drifts in the dipole-like magnetic field etc.), while in the SC maximum phase the heliospheric 11-year phenomena (the diffusion in the fluctuating magnetic field etc.) play the decisive role. As the initial grounds for such a hypothesis can serve the definitions of the maximum (the maximum in T and minimum in P branches) and minimum (the opposite situation) phases of the solar cycle on the Sun in the VKO classification. Besides the GCR effects observed during the maxima of solar activity (the double-peak structure of the modulation and the energy hysteresis) are approximately the same for different solar cycles and types of particles [Krainev et al., 1983, 1999], i.e., do not manifest the magnetic cycle. Contrary, the main GCR effect observed during the minima of solar activity (the different forms of the time profile of the intensity during successive minima of solar cycles) depends both on the polarity of the interplanetary magnetic field and on the sign of the particle's charge, although there is, probably, some smaller manifestation of the changes in the diffusion ( T branch) [Krainev and Webber, 1993b].

[17]  It should be noted that such hypothesis implies some specific scenarios for rather poorly studied processes in the heliosphere: the attenuation but not just rotation of the magnetic hemispheres with the global current sheet as the reversal of the high-latitude solar magnetic field proceeds; the formation of the regular and fluctuating heliospheric magnetic field also by the sunspot-like activity on the Sun and not only by the large-scale solar magnetic fields, etc.