Model approximation of cosmic ray spectrum

An analytical model which generalizes the equations describing the intensity of galactic cosmic rays (CR), including both processes, making it applicable in the inner heliosphere (where energy losses dominate) and outer heliosphere (influenced primarily by convection-diffusion processes) is derived. By a suitable choice of a parameter, the proposed model turns into two approximations: solution close to "force-field" model (describing the energy losses of CR in the inner heliosphere) and "convection-diffusion" equation (giving the reduction of CR intensity in the outer heliosphere). A mathematical relation between parameters in the proposed model and the modulation parameter Phi is derived. (C) 2011 Elsevier Ltd. All rights reserved.