The Influence of Corotating Regions of Interaction of the Solar Wind on Long-Term Variations in the Intensity of Galactic Cosmic Rays

An analysis of the data of spacecraft that scanned large areas of the heliosphere, as well as the results of magnetohydrodynamic calculations, indicates that corotating interaction regions of solar wind (SW), which are almost always present in the low- and mid-latitude heliosphere, sometimes strongly change the large-scale characteristics of the heliosphere that are important for long-term variations in the intensity of galactic cosmic rays (GCRs). In particular, for Carrington rotation no. 2066 (January–February 2008), these regions enhance magnetic fields in the inner (r < 3–5 AU) heliosphere and weaken them in the middle and far heliosphere, as well as significantly changing the polarity distribution of heliospheric magnetic fields. The assumption is made that in this situation the influence of the corotating interaction regions should lead to an increase in the GCR intensity in many regions of the heliosphere. This paper discusses the process of changing the polarity distribution of heliospheric magnetic fields due to the interaction of SW streams for Carrington rotation no. 2066 of different speeds, the simple model of the heliospheric magnetic field without an interaction between the SW streams of different speeds, as well as the results of numerical two-dimensional finite-difference calculations of longitude-averaged GCR intensity with the use of this model in comparison with a three-dimensional Monte Carlo calculation based on three-dimensional magnetohydrodynamic simulation of the heliosphere.