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

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

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

But We Predict Pretty Well Though Right?

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…

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

Reeves et al., 2016

Reeves et al., 2016

Energy (log scale) Reeves et al., 2016

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

perigee apogee perigee Energy Time perigee apogee Energy L-Shell

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

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

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

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

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

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

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

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

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

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

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

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

All Clear Region Maximum Flux Change Enhanced Fluxes

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

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

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

Ma et al., 2016

Ma et al., 2016

Ma et al., 2016

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

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