ROSES ID: NNH17ZDA001N Selection Year: 2017
Program Element: Focused Science Topic
Principal Investigator: Christina M.S. Cohen
Affiliation(s): California Institute of Technology
Gorby, Matthew Jay Other Professional University of New Hampshire, Durham
Schwadron, Nathan Allen Co-I University of New Hampshire, Durham
Linker, Jon A Co-I Predictive Science Inc.
Torok, Tibor Co-I Predictive Science Inc.
Caplan, Ronald M Co-I Predictive Science Inc.
Mewaldt, Richard A Co-I California Institute of Technology
Summary:Science Goals: Solar energetic particle (SEP) events can be a significant hazard to humans and technological infrastructure in space; predicting their intensity, location, and impacts is an imperative. Despite years of study, true predictive capabilities for SEP events continue to be hampered by open fundamental questions regarding their genesis close to onset from low in the corona, and how they populate the heliosphere. Studies combining the observations of SEPs near Earth (using, e.g., ACE, SOHO, and GOES) with those from the twin STEREO spacecraft have revealed longitudinal distributions that defy our general understanding of energetic particle transport, and point to the importance of magnetic field structure, coronal mass ejection injection and structure. Events such as 3 November 2011 indicate that SEPs can fill the inner heliosphere in ~30 minutes, much faster than expected. Statistical surveys of multi-spacecraft events show that the longitudinal distributions of SEPs vary substantially from event to event and the characteristics are, surprisingly, not clearly organized by rigidity but do depend on energy. Interpreting these observations requires an integrated approach that combines state-of-the-art analysis of SEP, solar, and interplanetary measurements with cutting-edge simulations starting from the Sun and extending through the low corona and inner heliosphere. By studying both individual events as well as general characteristics determined from survey studies, we will investigate key questions, including the role of coronal mass ejections (CMEs) and low-coronal shock formation in the acceleration of SEPs, the effect of field line connectivity on SEP transport, and the mechanisms that influence various SEP characteristics observed at 1 AU, such as rise time, longitudinal spreading, and compositional variation.