Effect of Corotating Interaction Regions of Solar Wind on GCR Intensity in 2D Modulation Problems

Сorotating interaction regions of solar wind flows with different velocities have actively been magnetohydrodynamically simulated for many years. However, the main goal is to predict heliospheric characteristics in Earth’s orbit, and so calculations are performed to distances of 1–1.5 AU. In the last decade, systematic magnetohydrodynamic calculations of corotating interaction regions up to much larger distances have appeared, which are necessary for studying recurrent variations in the intensity of galactic cosmic rays. Based on one of these calculations, we previously showed that, at least for one rotation of the Sun (Carrington rotation 2066, January–February 2008), the effect of corotating interaction regions on large-scale characteristics of the heliosphere that are important for GCR modulation and, therefore, the intensity averaged over longitude is significant. We assumed that the main principles of this effect of corotating interaction regions on GCRs can be studied both by 3D modeling of the GCR intensity and in much simpler 2D models. In this paper, we discuss the results, prospects, and shortcomings of such a 2D description of the effect of corotating interaction regions on the GCR intensity.