Trapped radiation models

D. HeynderickxBelgisch Instituut voor Ruimte-Aëronomie

Ringlaan 3, B-1180 Brussel

D.Heynderickx@oma.be

Galactic cosmic rays

Solar energetic particles

Secondary (albedo) radiation

Radiation belts

Earth’s Van Allen belts

• Particle motion: gyration, bounce, drift

• Guiding centre approximation: McIlwain’s (B,L) coordinates

• Model description: J(E,B,L)

Charged particle trapping

Trapped proton population

Trapped electron population

The South Atlantic Anomaly

• Low altitude part of radiation belts

• Tilt and shift of geomagnetic field: Fraser-Smith, Rev. Geophys., 25, 1, 1987

• Interaction with neutral atmosphere

http://www.spenvis.oma.be/spenvis/help/background/magfield/cd.html

The South Atlantic Anomaly (SAA)

Trapped proton variability

• Seasonal• Secular variation of

geomagnetic field• Impulsive

• Solar cycle

SAMPEX/PETAP-8 MIN

Directional proton flux >18 MeV at 500 km

Secular variation

Impulsive penetration

CRRESELE Equatorial L profiles

Parametrized in terms of Ap15: 15 day average of Ap

Available models

• De facto standard models: NASA AP-8 and AE-8– Advantages of the NASA models:

• Widespread usage (heritage)• Full spatial coverage and energy range

– Disadvantages of the NASA models:• Represent radiation environment of the 60’s and 70’s• Static models (but probably ok for long time averages)• Contamination by Starfish electrons

• Other models:– CRRESPRO, CRRESELE– NOAAPRO– POLE– SAMPEX/PET

Replacement of AP-8 and AE-8

• New models do not have sufficient spatial and/or temporal coverage and/or energy range

• Incomplete energy range can lead to misleading effects estimations

Standardisation efforts

• COSPAR Panel for Radiation Belt Environment Modeling (PRBEM) http://wwwe.onecert.fr/craterre/prbem/

• NASA working group meeting:– Focus efforts on selected regions of space and energy ranges to

expedite AP-8 and AE-8 replacement

– POLE model for GEO

– SAMPEX/PET+NOAAPRO for LEO protons

– ONERA/LANL GPS modelling for MEO

• RERMM study: use data from different satellites + Salammbô numerical simulation to produce ‘ad hoc’ models