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

Abstract

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