STK SEET Solar Energetic Particles (SEP)

The STK SEET Solar Energetic Particles (SEP) capability predicts the cumulative particle fluence expected during the lifetime of a mission using databases of particle observations from the Interplanetary Monitoring Platform (IMP) satellites and Geostationary Operational Environmental Satellites (GOES). Models include Emission of Solar Protons (ESP), JPL-91, and an update to JPL-91 due to Rosenqvist et al. (2005, 2007).

For additional background information, consult: SEET: Space Environment and Effects Tool for STK (PDF).

Options for STK SEET Solar Energetic Particles (SEP)

Option Description
Model Options are:
  • ESP - Determines the probability distribution for exceeding a fluence level during a mission, based on a maximum entropy technique. Includes data from the IMP and GOES, and proton observations from solar cycles 20 through 22.  Predictions for proton fluence are made from integral energy channels from >1 MeV through > 100 MeV. This model also includes a formulation of the worst-case-event fluence expected.
  • JPL91 - Expected proton fluence for satellite design using observationsobtained between 1963 and early 1991 from the IMP and OGO 1 satellites. Estimated total proton fluence over a mission is dominated by the probability of the occurrence of large events during solar maximum. The main parameter of importance is the average number of events occurring during the mission.
  • Rosenqvist - Update to the JPL-91 model including data from the GOES satellites using observations from January 1974 to May 2002.  Updates include the mean and standard deviation of the probability distributions and the average number of events expected during active years.
Mission Duration

Time interval over which the SEP model determines probabilistic thresholds for the fluence level. Valid from 1.0 to 22.0 years inclusive.
Energies

Energy Bin List in MeV for which Fluences to Exceed for specified probabilities will be computed. Values from the default list may be removed; otherwise the list cannot be modified.
Report Probability

Probability threshold for producing the fluence-energy spectrograms. A probability of 95% means the return of the highest fluence for which the probability of occurrence exceeds 95%, as characterized by a Poisson distribution.

One should specify 5% report probability if 95% confidence is required.

Feynman, J., G. Spitale, J. Wang, and S. Gabriel, Interplanetary Proton Fluence Model: JPL 1991, J. Geophysics. Res., 98, 13281 (1993).

Rosenqvist, L., Hilgers, A., Evans, H., Daly, E.A., Hapgood, M., Stamper, R., Zwickl, R., Bourdarie, S. and Boscher, D. : Toolkit for Updating Interplanetary Proton-Cumulated Fluence Models, Journal of Spacecraft and Rockets, Vol. 42, No. 6, 2005.

Xapsos, M. A., Stauffer, C., Jordan, T., Barth, J.L., and Mewaldt, R.A., Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra, IEEE Trans. On Nucl. Science, 54, No. 6, 2007.