1. The Van Allen Radiation Belts: What I Would Like Machine Learning to Learn
Geoffrey Reeves
LANL.gov
NewMexicoConsortium.org
European Space Weather Week 2016

2. The Van Allen Radiation Belts: Challenges and Opportunities
for Space Weather Forecasting
Geoffrey Reeves
LANL.gov
NewMexicoConsortium.org
European Space Weather Week 2016

3. The Radiation Belt Revolution
The 25 years from CRRES to Van Allen Probes exposed new forecasting challenges
Shock events (although rare) can accelerate electrons to 10s MeV in minutes
‘Normal’ acceleration events can accelerate electrons to many MeV in hours
Bigger storms do not necessarily create bigger radiation belt events
Storms can either increase or decrease radiation belt fluxes
Wave-particle interactions are responsible for acceleration, transport, and loss
The solar wind driving / coupling function is not well-understood
Radiation Belt responses are different at different energies and at different L-shells

4. But We Predict Pretty Well Though Right?

5. Yes… But… We predict one energy in one orbit pretty well
Predictions are good on longer time scales but we don’t predict changes very well
Predictions focus on single energies not spectral hardness
Global Data Assimilation models (DREAM, VERB, BAS…) are mature but operational prototyping is just beginning
We still can’t even guess whether a CME / CIR will produce net increases or decreases in fluxes in a given orbit of interest
When things are bad we can’t tell operators how long they will stay bad, which energies will be bad, or which orbits will be bad
Etc…

6. The Belts at different Energies and L-shells
1.5 MeV
0.5 MeV
0.25 MeV

7. Reeves et al., 2016

8. Reeves et al., 2016

9. Energy (log scale)
Reeves et al., 2016

11. This is a Complicated Prediction Problem - Or Is It?
Quiescent State
Enhanced State
ΔT = 45 hours

12. perigee
apogee
perigee
Energy
Time
perigee
apogee
Energy
L-Shell

13. Active - Enhanced State
4 MeV
1 MeV
Energy
100 keV
50 keV
L-Shell

14. Active - Enhanced State
4 MeV
Location of Boundary
1 MeV
Energy
Location of Flux Peak
100 keV
50 keV
L-Shell

15. The Enhancement Decays
Quiescent State
4 MeV
The Enhancement Decays
Energy and L-dependent
“Bite-out” at intermediate energies
1 MeV
Energy
100 keV
50 keV
L-Shell

16. All of these are newly enhanced Electron Fluxes
Active - Enhanced State
4 MeV
1 MeV
All of these are newly enhanced Electron Fluxes
Energy
100 keV
50 keV
L-Shell

17. No Change in Electron Flux
Active - Enhanced State
4 MeV
No Change in Electron Flux
1 MeV
Energy
100 keV
50 keV
L-Shell

18. March 17, 2013 Pre-Enhancement Enhancement Event Energy L-Shell

19. May 1, 2013
Pre-Enhancement
Enhancement Event
Energy
L-Shell
L-Shell

20. May 25, 2013
Pre-Enhancement
Enhancement Event
Energy
L-Shell
L-Shell

21. June 1, 2013
Pre-Enhancement
Enhancement Event
Energy
L-Shell
L-Shell

22. June 7, 2013
Pre-Enhancement
Enhancement Event
Energy
L-Shell
L-Shell

23. April 23, 2013 Pre-Enhancement Enhancement Event Energy L-Shell

24. Post-Event
Flux Peak
Post-Event
Boundary
Pre-Event
Boundary
Slot-Filling
Energies

25. All Clear Region
Maximum Flux Change
Enhanced
Fluxes

26. How Long Will Things Stay Bad? What L-shells? What Energies?

27. Active - Enhanced State
4 MeV
1 MeV
Energy
100 keV
50 keV
L-Shell

28. The Enhancement Decays
Quiescent State
4 MeV
The Enhancement Decays
Energy and L-dependent
“Bite-out” at intermediate energies
1 MeV
Energy
100 keV
50 keV
Reeves et al., 2016
L-Shell

29. Ma et al., 2016

30. Ma et al., 2016

31. Ma et al., 2016

32. Conclusions
The radiation belts are highly structured in Energy and L-shell
There is considerable event-to-event variation, but… There are characteristics features in energy and L that are consistent and repeatable
e.g. Enhancements at a given L-shell are always more common at lower energies == Enhancements at lower energies always penetrate more deeply than at higher energies.
We may be able to relate those general probability distributions to solar wind driving conditions

33. Conclusions
This coherence should also make it easier to make general predictions based on limited observations
e.g. Can we predict the slope and intensity of the maximum in electron fluxes as a function of energy and L?
Energy and L-shell dependent loss rates should be even easier to predict because the physical process is clearer
Once we know the condition of the enhanced belt we should be able to predict where, at what energies, and how long things will be bad