Deconvolution of interplanetary transport of solar energetic particles

Abstract

We address the problem of deconvolving the effects of interplanetary transport on observed intensity and anisotropy profiles of solar energetic particles with the goal of determining the time profile and spectrum of particle injection near the Sun as well as the interplanetary scattering mean free path. Semi-automated techniques have been developed to quantitatively determine the best fit injection profile, assuming (1) a general piecewise linear profile or (2) a Reid profile of the form [C/(t - t0)]exp[-A/(t - t0) - (t - t0)/B]. The two assumptions for the form of the injection profile yielded similar results when we tested the techniques using ISEE 3 proton data from the solar flare events of July 20, 1981 (gradual flare), and January 2, 1982 (impulsive flare). For the former event, the duration of injection was much shorter for protons of higher energy (75-147 MeV), which may be interpreted as indicating that the coronal mass ejection-driven shock lost the ability to accelerate protons to ∼100 MeV after traveling beyond a certain distance from the Sun. Copyright 1998 by the American Geophysical Union.