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ISWAT H3: Particle Radiation Environment in the Heliosphere: Updates

Presenter: Kathryn Whitman

Moderator: Jingnan Guo

Co-Moderator: Lulu Zhao�

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Source of energetic particles in the heliosphere

Galactic Cosmic Rays

There are different types of radiation sources in the heliosphere, including galactic cosmic rays coming from outside the solar system and being affected by the time-and spatial varying solar wind and interplanetary magnetic fields. Another type of radiation at energies below about 100 MeV/nuc is ACRs which originally are interstellar neutral atoms. They penetrate into the heliosphere and become ionized mainly by solar radiation via photoionization and/or by solar wind ions via charge exchange.

Then these particles are picked up by the solar wind magnetic field and convect into the outer heliosphere. They can get accelerated at the termination shock and get transported back into the heliosphere. Solar Energetic particles are accelerated during solar eruptions via shock and/or magnetic reconnection. ESPs are actually a kind of SEP which are detected upon the shock arrival as they are accelerated by the shock in the interplanetary space. And CIRs may also be associated with shocks which can accelerate particles to a certain energy. But normally they are not energetic enough to be of radiation concern. So we are not including them in the current review paper.

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Roadmap Paper content

Introduction
Solar Energetic Particles
Ground Level Enhancement
Galactic Cosmic Rays
Anomalous Cosmic Rays
Future focuses and Recommendations

Conclusion

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Key Phys	Key Physics	Existing Key observations	Limitations and Open questions
Energization	Shock acceleration (Shock drift acceleration, Diffusive shock acceleration)	EUV Shock waves, Coronagraphs of CMEs, Radio emission, IP shock strength & orientation, SEP composition & spectral properties	What is the key physics at scales and locations that cannot yet be observed? How to distinguish CME-associated SEPs from flare-accelerated ones? Where exactly does the flare acceleration takes place? How are particles released? What is the exact role of current sheet & turbulence during reconnection? What is the shock condition? How does the shock distribute in space and evolve in time? How does the shock condition affect the acceleration process? What determines the starting and ending energy of the accelerated SEPs? How to explain observed energy-dependence of composition in some cases? How the variability of the SEP events (size, composition, spectral features) is correlated to the acceleration process?
Energization	Reconnection acceleration (current sheet, turbulence, magnetic islands)	Remote-sensing images (flare, jets, flux-rope, coronal dimming), Multi-wavelength obs (EUV, X-ray, γ-ray, Radio emission), SEP composition (enhanced 3He, Ultra heavy ions)
Transport	Field aligned	Magnetic connectivity, Pitch angle, Anisotropy (with limited resolution), onset time, spectral information and spatial distribution by multi-view observers (not yet sufficient)	What is the actual field connectivity (especially with SW disturbances)? How the field evolves dynamically in space and time? What is the relative role of extended source and cross-field transport? What is the relative role of particle scattering and field meandering? How are the SEP properties modified during the propagation? How to explain observations against existing acceleration/transport theories?
Transport	Cross field
Conditions	Plasma + Structures	Solar observation (magnetic field of the photosphere, Coronal holes) Insitu SW disturbance, Near-Sun and in-situ observations of CMEs	How to identify the properties of the SEP source at the back-side of the Sun? What is the IMF and SW condition at close solar distances? What are the properties of SW disturbances missing the observer?
Conditions	Seed population	Composition, Relative abundance, Energy spectra	What are the composition & spectrum of super-thermal particles? What is the seed population variability? What are their properties close to the Sun? What is the spatial distribution (longitudinal, radial) of seed particles?

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Next 10+ years

USING CURRENT MISSIONS:

synergistic multispacecraft observation & analysis
exploiting more accurate angular information

WITH FUTURE MISSIONS:

multi-scale observation & analysis
Larger energy ranges

Next 5+ years

CONTINUOUS MONITORING (CURRENT & FUTURE MISSIONS):

improve our forecasting and nowcasting capabilities
maximize feasibility of empirical & machine learning models

KEY REQUIREMENTS TO IMPROVE MODELING CAPABILITIES:

Develop and Utilize more combined modelling-observational approaches
Coordinate different modeling products and optimize usage in different regimes
Consider planetary environment for better studying of event’s impact on planets
Adopt and cross-verify different modeling approaches
Employ heliospheric models with more realistic solar wind parameters and dynamic background conditions

KEY REQUIREMENTS

TO IMPROVE OBSERVATIONAL CAPABILITIES

multi locations
multi scales
wide energy range
more angular information

RECOMMENDATIONS

SYSTEM VIEW of heliospheric energetic particles together with other space weather phenomena (e.g., studied by other ISWAT clusters https://iswat-cospar.org)

Future Recommendations

We provided a table for future recommendations stressing using current mission data to carry out multisc analysis and exploiting more accurate angular information in the next 5 years.

And we stress a system view of the energetic particle radiation environment together with other sw phenomena studied by other clusters.

Energetic particle people should collaborate more with the solar physics, with the CME guys, with the planetary community and with the industry people. We need to learn from others and ask for their help to better understand the source where these particles come from and the media that they propagate through. And we also need to understand for example what the agency and industry need, for instance the exact input they need for their aviation radiation mitigation purposes.

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Action Teams

H3-01 (active): SEP Validation (Team lead: Kathryn Whitman, NASA/SRAG)
H3-02 (active): Understanding the Suprathermal Seed Population (Team Lead: Maher Dayeh, SWRI)
H3-03 (paused): Heliophysics for Artemis and Beyond (Lead: Alexa Halford)
H3-04 (new): CLEAR: All-Clear SEP Predictions (Lead: Lulu Zhao, UM)

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H3-01: SEP Validation

Team Leads: Katie Whitman, Phil Quinn, Hazel Bain, M. Leila Mays
Objectives:

Organize community campaigns to evaluate how well different models/techniques can predict historical SEP events throughout the heliosphere
Establish metrics agreed upon by the community
Provide a benchmark against which future models can be assessed against
SEP Scoreboard: Add more models to the scoreboard database/display, gather feedback on the displays, serve forecasts. Begin validation of scoreboard forecasts and investigate automated real-time validation.

Session Time: Tuesday AM1, PM1 @Martinique, with H3-02 Thursday AM2

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H3-01: SEP Model Validation

Tuesday AM1�SEPVAL Community Validation Challenge Results

Tuesday PM1�SEP Scoreboards real time SEP forecasting results

SEPVAL 2023 (Europe)

ESWW, Toulouse, France

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H3-02: Understanding the Suprathermal Seed Population

Team Leads: Maher Dayeh
Objectives:

examine the feasibility of determining a reliable seed spectrum that can be used by SEP modelers. We utilize multi-spacecraft observations of suprathermal particles and other validated modeling and simulation tools.

Session Time: Thursday PM1, PM2 @Trinidad
Joint with H3-01: Thursday AM2 @Jamaica

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H3-04 (New):CLEAR: All-Clear SEP Predictions

Team Leads: Lulu Zhao
Objectives:

We focus on developing capabilities for robust and quantifiable forecasts of space radiation levels of up to 24 hours. Specifically, the framework will:

1) provide pre-eruption probabilistic forecasts of SEP events,
2) nowcast and forecast the post-eruption SEP key parameters, including the time-dependence and maximum flux, onset, peak and end times, and the spectral characteristics, and
3) predict periods of SEP intensities below a preset threshold to issue all-clear forecasts.

Session Time: Wednesday AM1, AM2 @Trinidad

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H3-04 (New):CLEAR: All-Clear SEP Predictions

Build a benchmark SEP dataset that would be beneficial to the entire community for both operational and scientific purpose
Build a prediction framework that integrate the current state-of-the-art empirical, machine learning, and first principle-based models
The framework will be validated and tested in the laboratory environment and ready for transition to proving ground.
Plug-and-play modularized framework that enables the integration of new models from the community.

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Synergy with other clusters

Inter and intra cluster collaborations are crucial.
Understanding the forecast of SEPs rely on the understanding and modeling of the ambient solar wind properties (S1, S2, H1, H2) and the solar eruptive events (S3, H3).
Accurately modeling of the SEPs at Earth and other planets could help understand and forecast other space weather phenomenon associated with SEPs (e.g. H4, G3), which is essential for mitigating radiation risks associated with space missions.