Forecasting of cosmic rays intensities with HelMod Model

Abstract

HelMod model allows one to describe how solar modulation affects the propagation of galactic cosmic rays (GCR) through the heliosphere with an accuracy of the level of actual experimental uncertainties. The GCRs mainly constitute the high energy population of the so-called space radiation environment. The model treats the physical processes involved in solar modulation, like diffusion, particle drift, convection and adiabatic energy losses, and it embeds a description of both the inner and outer heliosphere. To obtain the modulated intensities, the model requires the knowledge of a few time-dependent heliospheric quantities, i.e., sunspot number, tilt angle of the neutral current sheet, solar wind speed and density, and interplanetary magnetic field. Using historical records, we present a template-based procedure that allows one to predict the heliospheric parameters for coming years, and, in turn, the forecasted modulated spectra. The forecasting templates reconstruct the typical time variation along with solar cycles and may be tuned to the current solar cycle. We estimate that the uncertainty of the forecasted cosmic rays intensity is below 5% (±10% at 68% C.L.) on average for short time predictions (up to 4 years), and below 15% (±(20-25)% at 68% C.L.) for long time predictions (up to 11 years).