BEXCO - Room C(108)
[SH048] Searching for Extreme SEP Events with STEREO
Ground Level Enhancements (GLEs) are a particular class of solar energetic particle (SEP) events in which the particle spectrum is hard enough to produce effects on the Earth’s surface. Historically a GLE had to be observed by two separate ground-based monitors to be added to the informal ‘GLE list’ (http://neutronm.bartol.udel.edu/~pyle/GLE_List.txt). As these events are among the most energetic of SEP events, they are a clear space weather concern and understanding the conditions under which they occur and the processes that create them is critical for improving our predictive capabilities. By their very definition, GLEs cannot be identified with only space-based instrumentation or at locations far from Earth, yet as we increasingly send instrumentation to distant locations, our need for predicting space weather throughout the heliosphere rises. Using the 60-100 MeV proton intensities observed during the 13 Dec 2006 GLE by the STEREO spacecraft (when they were still close to Earth) as a guide, we have identified several SEP events observed by STEREO which we dub ‘GLE-Wannabe’ (GLE-W) events. None of these events were strong enough at Earth to register as a GLE, but had Earth been in the STEREO location, they might have been. We present SEP analysis of these events at STEREO and compare the spectra and composition to that of previously analyzed GLEs, particularly those with comparable observations upstream of Earth. Additionally we analyze the magnetic connection between the spacecraft and the expanding coronal mass ejection driven shock as a function of time using the WSA-ENLIL model. We discuss the SEP results in light of these simulations and their implications for the generation of these GLE-W events.