Last Updated: 05/20/2024


Version: v1

SEPSTER2D is an empirical model to predict SEP event-integrated and peak intensity spectra between 10 and 130 MeV at 1AU, assuming an energy-dependent 2D Gaussian spatial distribution, and accounting for the correlation between the intensity and the speed of the parent CME, and the magnetic-field-line connection angle. The magnetic footpoints of the IMF field lines passing through the observer (Earth, STEREO-A and -B) are estimated at CME first appearance time and at a 2.5 Rs radial distance based on a simple IMF Parker spiral model.


Predicted intensities are expected to overestimate the observations for relatively slow (<600km/s) CMEs and narrow SEP events. SEP intensities above 130 MeV are based on spectral extrapolations and are characterized by large uncertainties.


CME speed, direction and first appearance time from DONKI; solar wind speed from ACE/DSCOVR/STEREO


SEP peak and event-integrated intensities (both differential and energy-integrated) above 10 MeV, along with corresponding uncertainties. Time of peak intensity (added in version 1.1 and later)

Change Log

Upgraded to Version 1.1 on March 21, 2022 at the CCMC. List of changes includes:

  • Calculation of peak intensity times added

Upgraded to Version 1.2 on July 3, 2023 at the CCMC. List of changes includes:

  • Solar wind speed is now calculated individually for each CME, paying attention to data gaps.
  • For historical events, the OMNI dataset via CDAWEB HAPI API is now being used.
  • For real-time runs, the iSWA HAPI API is now being used to fetch real-time solar wind data.
  • A correction factor has been implemented to fix the model prediction overestimate for relatively slow CMEs.
  • Added calculation of SEP event end times.

Version 1.3 includes a fix to filter out and prevent invalid, elevated solar wind speeds from being used for the predictions, and a change to use the Leading Edge (LE) CME measurements only for SEPSTER2D predictions.


  • Heliosphere / Inner Heliosphere

Space Weather Impacts

  • Solar energetic particles - SEPs (human exploration, aviation safety, aerospace assets functionality)


  • Solar Energetic Particles



Code Languages: C/C++


Publication Policy

Bruno, A., Richardson, I.G. Empirical Model of 10-30 MeV Solar Energetic Particle Spectra at 1 AU Based on Coronal Mass Ejection Speed and Direction. Sol Phys 296, 36 (2021).

In addition to any model-specific policy, please refer to the General Publication Policy.