A TwinCME Scenario for Ground Level Enhancement E

Authors: G Li R Moore R A Mewaldt L Zhao A W Labrador

Publish Date: 2012/01/17

Volume: 171, Issue: 1-4, Pages: 141-160

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Abstract

Ground Level Enhancement GLEs events are extreme Solar Energetic Particle SEP events Protons in these events often reach ∼GeV/nucleon Understanding the underlying particle acceleration mechanism in these events is a major goal for Space Weather studies In Solar Cycle 23 a total of 16 GLEs have been identified Most of them have preceding CMEs and insitu energetic particle observations show some of them are enhanced in ICME or flarelike material Motivated by this observation we discuss here a scenario in which two CMEs erupt in sequence during a short period of time from the same Active Region AR with a pseudostreamerlike preeruption magnetic field configuration The first CME is narrower and slower and the second CME is wider and faster We show that the magnetic field configuration in our proposed scenario can lead to magnetic reconnection between the open and closed field lines that drape and enclose the first CME and its driven shock The combined effect of the presence of the first shock and the existence of the open close reconnection is that when the second CME erupts and drives a second shock one finds both an excess of seed population and an enhanced turbulence level at the front of the second shock than the case of a single CMEdriven shock Therefore a more efficient particle acceleration will occur The implications of our proposed scenario are discussed

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