This proposal includes seven collaborators and will systematically examine the longitude dependence of solar energetic particle (SEP) characteristics through studying: (1) solar data from SOHO, TRACE, Yohkoh, and RHESSI; (2) SEP data from the Solar Isotope Spectrometer (SIS) and the Ultra Low Energy Isotope Spectrometer (ULEIS), both on the Advanced Composition Explorer (ACE) spacecraft; and (3) radio data from Wind/WAVES, Culgoora, and Bruny Island, Australia. Identified SEP events will be characterized according to several criteria, including elemental abundances and ratios measured at a range of MeV energies per nucleon. Radio signatures, shock transit speeds, CME speeds, flare magnitudes, flare durations, flare longitude/magnetic connections (and other relevant parameters) will then be examined in terms of this characterization. Particular focus will be placed on radio type III bursts as indications of open magnetic field lines and the solar connection to the identified flares of interest, as determined by the potential field source surface (PFSS) model. How the characterization of the SEP events depends on solar longitude (accounting for the magnetic connection) will be important in evaluating and constraining any theory attempting to provide explanations for the large variation in the energy-dependent elemental composition observed in SEP events. This effort will help quantify the plausibility of the currently competing hypotheses.
Results will be disseminated to the broader community through campaign web sites, peer-reviewed scientific journals, and public newsletters, as well as through future SHINE meetings, where students are especially encouraged (and often funded) to attend. The benefit of this research to society is strongly related to the increasing need to predict space weather and the SEP-related radiation hazards faced by astronauts, sensitive space equipment, and even some commercial airline flights. In particular, SEP longitude dependence is crucial for forecasting the effects at locations far from the Sun-Earth line, as will be necessary within NASA's new Space Exploration Initiative. In order to make useful space weather predictions at any location, understanding the connection between what is observed remotely at the Sun and the resulting SEP event is critical. The proposed research furthers this endeavor in an area of currently vigorous debate. This proposal employs two women (one being the PI) and includes funds for training an undergraduate student. Many of the collaborators have a strong history of collaboration in the fields of radio spectrometry, solar physics, and particle physics, as well as in giving presentations to young scientists and students at colleges, high schools, and middle schools.