The solar modulation effect of cosmic rays in the heliosphere is an energy-, time-, and particle-dependent phenomenon which arises from a combination of basic particle transport processes such as diffusion, convection, adiabatic cooling, and drift motion. Making use of a large collection of time-resolved cosmic-ray data from recent space missions, we construct a simple predictive model of solar modulation which depends on direct solar-physics inputs: the number of solar sunspots and the tilt angle of the heliospheric current sheet. Under this framework, we present calculations of cosmic-ray proton spectra, positron/electron and antiproton/proton ratios and their time dependence in connection with the evolving solar activity. We report evidence for a time-lag ΔT=8.1±1.2 months, between solar activity data and cosmic-ray flux measurements in space, which reflects the dynamics of the formation of the modulation region. This result enables us to forecast the cosmic-ray flux near Earth well in advance by monitoring solar activity
@article{arxiv.1707.06916,
title = {Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays},
author = {Nicola Tomassetti and Miguel Orcinha and Fernando Barao and Bruna Bertucci},
journal= {arXiv preprint arXiv:1707.06916},
year = {2018}
}