On the Estimation of Solar Energetic Particle Injection Timing from Onset Times near Earth
- 20 June 2005
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 626 (2), 1131-1137
- https://doi.org/10.1086/430293
Abstract
We examine the accuracy of a common technique for estimating the start time of solar energetic particle injection based on a linear fit to the observed onset time versus 1/(particle velocity). This is based on a concept that the first arriving particles move directly along the magnetic field with no scattering. We check this by performing numerical simulations of the transport of solar protons between 2 and 2000 MeV from the Sun to the Earth, for several assumptions regarding interplanetary scattering and the duration of particle injection, and by analyzing the results using the inverse velocity fit. We find that, in most cases, the onset times align close to a straight line as a function of inverse velocity. Despite this, the estimated injection time can be in error by several minutes. Also, the estimated path length can deviate greatly from the actual path length along the interplanetary magnetic field. The major difference between the estimated and actual path lengths implies that the first arriving particles cannot be viewed as moving directly along the interplanetary magnetic field.Keywords
This publication has 26 references indexed in Scilit:
- Relativistic solar neutrons and protons on 28 October 2003Geophysical Research Letters, 2005
- Spaceship Earth Observations of the Easter 2001 Solar Particle EventThe Astrophysical Journal, 2004
- Energetic particle propagation in the inner heliosphere as deduced from low‐frequency (<100 kHz) observations of type III radio burstsJournal of Geophysical Research, 2003
- Energetic Particle Observations during the 2000 July 14 Solar EventThe Astrophysical Journal, 2002
- The Rigidity Dependence of Solar Particle Scattering Mean Free PathsThe Astrophysical Journal, 2000
- Proton and electron mean free paths: The Palmer consensus revisitedThe Astrophysical Journal, 1994
- Distribution of flares on the sun - Superactive regions and active zones of 1980-1985The Astrophysical Journal, 1987
- Focusing anisotropy of solar cosmic raysJournal of Geophysical Research, 1986
- The effect of adiabatic focusing upon charged-particle propagation in random magnetic fieldsThe Astrophysical Journal, 1976
- Diffusion of Charged Particles in a Random Magnetic FieldThe Astrophysical Journal, 1973