Linking Energetic Storm Particles to their Upstream Physical Conditions and Shock Properties
ROSES ID: NNH17ZDA001N Selection Year: 2017
Program Element: Focused Science Topic
Principal Investigator: Maher A Dayeh
Affiliation(s): Southwest Research Institute
Project Member(s):
Kostan, Travis Co-I Southwest Research Institute
Burns, Cheryl Collaborator Self
Ebert, Robert W Co-I Southwest Research Institute
Gonzales, Edith M Collaborator Self
Hebert, Vanessa Collaborator Self
Desai, Mihir I Co-I Southwest Research Institute
Li, Gang Co-I University Of Alabama, Huntsville
Berger, Laura L Collaborator Self
Summary:
Current Understanding: Enhancements of >0.1 MeV/nucleon ions near 1 AU in association
with the passage of an interplanetary (IP) coronal mass ejection (ICME) are often referred to as
energetic storm particle (ESP) events. The primary candidate of producing these enhancements is
diffusive shock acceleration (DSA). ESPs can produce significant increases in the near-Earth
particulate radiation and pose severe hazards to astronauts and hardware in space. Physical
parameters thought to affect ESP production include IP shock properties (e.g., speed, strength,
obliquity) and upstream conditions ahead of the propagating shock (e.g., turbulence, seed
populations, SW and IMF conditions). While several observational studies and theories have
attempted to link ESP production to these drivers, reliable prediction of ESP properties (e.g.
intensities, spectra, abundances), including their event-to-event variability, has so far proven
elusive, indicating an incomplete understanding of how ICME-driven IP shocks accelerate ESPs.
Goal and Science Questions: Our overarching goal is to identify the dominant upstream and
shock parameters that influence ESP properties and lead to their event-to-event variability,
thereby advancing current understanding of ICME-driven shock particle acceleration. We will
also determine whether these drivers can be used to predict ESP properties at 1 AU. We will
achieve this goal by answering the following three science questions:
Q1. What is the relationship between upstream conditions, ESP properties, and IP shock
properties at 1 AU?
Q2. How do upstream conditions and IP shock properties affect ESP production and properties?
Q3. Can upstream conditions and IP shock properties be used to predict ESP properties at 1 AU?
Methodology: We use energetic H-Fe ion, plasma and magnetic field measurements from ACE,
Wind, and STEREO-A&B during solar cycles 23 and 24. Using specific criteria, we will identify
all shocks and ESP events measured at 1 AU. For each ESP and when available, we will derive a
matrix of parameters describing the upstream conditions, IP shock, and ESP. Statistical and
correlation studies will follow to pinpoint the dominant drivers that influence ESP properties
(Q1). Once the Upstream-Shock-ESP linkage is determined, we will utilize the Particle
Acceleration and Transport in the Inner Heliosphere (PATH) model to explore the influence of
these dominant drivers on ESP properties. PATH model inputs, constrained by observations, will
be varied systematically to isolate the influence of each potential driver on ESP intensities,
spectra and abundances (Q2). Using the parameter matrix derived in Q1, we will utilize Machine
Learning algorithms to determine if and how upstream and shock parameters can be used to
predict ESP properties (Q3). The relationships uncovered in these analyses are expected to lead
to a more complete understanding of ICME-driven particle acceleration at 1 AU.
Relevance to NASA and LWS: Our project responds directly to the second Focused Science
Topic (FST) and to two LWS Program Science goals, as indicated in the special FST
contributions elsewhere in this proposal. Results are also relevant to two science goals of the
2012 Solar and Space Physics Decadal Survey, and to a key strategic goal of NASA " s
Heliophysics Division, i.e., understand the Sun and its interactions with the Earth and the solar
system, including space weather
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