Using ENLIL and SEPMOD to Evaluate Shock Connectivity Influences on Gradual SEP Events Observed with STEREO and ACE
Abstract
An observer's magnetic field connection to a SEP-producing interplanetary shock (or compression) source often appears to provide a good indicator of whether or not a SEP event occurs. As a result, some tools for SEP event modeling make use of this finding. However, a key assumption of these approaches is that the interplanetary magnetic field and heliospheric shock geometries are known throughout the event(s). We consider examples of SEP time profile calculations obtained with combined ENLIL and SEPMOD modeling where the results compare well with observations at multiple inner heliosphere sites, and compare them to cases where such comparisons show a relative lack of agreement. ENLIL does not include the shock inside 21 Rs or CME/ICME ejecta magnetic fields, but for the agreeable cases this does not seem to make a big difference. The number, size, speed and directions of related CMEs/ICMEs, and ENLIL field line geometry appear to play the most critical roles. This includes the inclusion of prior and parallel events that affect both the ICME propagation and magnetic field geometry and strength along the observer field line. It seems clear that if a SEP forecasting system is desired, we must continue to have instrumentation that allows us to specify global CME/ICME initiation geometry (coronagraphs, XUV/EUV imagers) and background solar wind structure (magnetographs).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMSH33C..02L
- Keywords:
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- 7513 Coronal mass ejections;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7514 Energetic particles;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7519 Flares;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7524 Magnetic fields;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY