Shock as a black box 2. Effects of adiabatic deceleration and convection included

Abstract

This paper presents an expanded version of a numerical scheme to model the intensity and anisotropy time profiles of energetic particle events associated with interplanetary shocks. The acceleration at the shock is treated as a black box; the subsequent particle propagation is described in a transport model which in addition to the effects of focusing and pitch angle scattering also considers convection with the solar wind and adiabatic deceleration. In addition, the pitch angle transport associated with the passage of energetic particles through the shock is included. Owing to the special description of the shock, corotation is considered too. Results of the model with and without solar wind effects are compared. Owing to the continuous supply of fresh particles from the shock, the influence of solar wind effects is always smaller than that in the case of a simple solar injection for the same set of parameter values. Depending on the radial development of the shock efficiency and the location of the observer relative to the nose of the shock, at 1 AU the effects of adiabatic deceleration and convection are important only at energies below a few MeV. Solar wind effects always show a stronger influence on profiles observed at the shock's eastern flank than those close to the central meridian or on the western flank. Owing to the inclusion of adiabatic deceleration, particle profiles at different energies are coupled: the assumption of a rigidity dependent radial development of the shock's acceleration efficiency, that is, a steepening of the injection spectrum, is required to reproduce the observed energy dependence of intensity time profiles.