1. INTERNATIONAL STANDARDIZATION ORGANIZATION TECHNICAL SPECIFICATION 15391 Space Environment (Natural and Artificial) Probabilistic model of fluences and peak fluxes of solar energetic particles Part I Protons (Version 2004) by R.A. Nymmik

2. ISO WG 4, Moscow 2004 R.A.Nymmik The present Standard is intended for calculating the fluences and peak fluxes of solar energetic protons, which are expected to occur during a given time interval at any known or predicted solar activity level and to exceed their calculated sizes with a given probability. In combination with the ISO 15390 Standard – Model of Galactic Cosmic rays, this Standard provides a description of the radiation environment, induced by high-energy particle fluxes on the Earth’s orbit in interplanetary space and serves as the basis for describing the radiation environment during interplanetary missions, and for calculating particle fluxes, penetrating into near-Earth spacecraft and space station orbits.

3. ISO WG 4, Moscow 2004 SEP flux model - version 2004 is the MSU model, corrected according to the results of study of the systematical errors and reliability of the different Solar Energetic protons flux data, measured on different spacecrafts by different instruments. corrected according to the results of study of the systematical errors and reliability of the different Solar Energetic protons flux data, measured on different spacecrafts by different instruments.R.A.Nymmik

4. ISO WG 4, Moscow 2004 Some examples of systematic errors in the measurement results A convenient technique of multiple analysis of SEP events fluxes and energy spectra is the logarithmic mean of a set of events: R.A.Nymmik

5. ISO WG 4, Moscow 2004 R.A.Nymmik An example of systematic errors in the measurement results The ratio of the sizes of the SEP events peak fluxes, measured on the IMP-8 and GOES-7 spacecrafts versus energy

6. ISO WG 4, Moscow 2004 R.A.Nymmik The distribution of peak flux ratios for the SEP events, recorded by GOES-6 and GOES-7 measurement channels. An example of systematic errors in the measurement results

7. ISO WG 4, Moscow 2004 R.A.Nymmik An example of systematic errors in the measurement results The channel 10 of CPME insrument on IMP-8

8. ISO WG 4, Moscow 2004 The distribution functions for the SEP events which occurred during 1986- 2002 according to IMP-8 and GOES-7&8 spacecrafts measurements of E30 and E300 MeV proton fluxes and their approximations R.A.Nymmik An example of systematic errors in the measurement results

9. ISO WG 4, Moscow 2004.R.A.Nymmik Reliability of the different measurement data 13 GLE events of 22 cycle Coincide: 1.GOES-7 (uncorrected) 2.METEOR 3.Neutron monitors Differ: 1.IMP-8 2. GOES-7 (corrected)

10. ISO WG 4, Moscow 2004 Main errors of the JPL-91 (Feynman et al.) and JPL-91 (Feynman et al.) and ESP (Xapsos et al.) models ESP (Xapsos et al.) models 1. Neglecting the SEP fluxes in the “Quiet” Sun period (W<40) 2. Assumption that SEP event frequency and flux sizes are the same for the whole “Active” Sun (W>40)period R.A.Nymmik

11. ISO WG 4, Moscow 2004 R.A.Nymmik The proton fluence for SEP events (circles) and GCR (asterisks) during the last SA minimum, covering the 4- year period from Dec. 1993 to Nov. 1997. The energy spectra are differential. Neglecting the SEP fluxes in the “Quiet” Sun period (W<40)

12. ISO WG 4, Moscow 2004 R.A.Nymmik The logarithmicaly averaged annual proton fluence energy spectra measured by GOES (for years with solar activity W>100 and 40<W<100). JPL-91 model interprets these fluences as detected with different probability (from 0.1 o 0.7), instead of as caused by different SA! Assumption that SEP event frequency and flux sizes are the same for the whole flux sizes are the same for the whole “Active” Sun (W>40)period

13. ISO WG 4, Moscow 2004 R.A.Nymmik Another methodological shortcomings of the JPL-91 and ESP models are: 1. the nonphysical (“engineering” or “commercial”) definition of the “SEP event”, 2. use of partially unreliable databases 3. the non-optimal methods for analysing SEP – SA connection, 4. the limited technique of the separate distribution functions for different energy particle fluxes and fluences, 5. the irrelevant form of distribution function used in JPL-91 model.

14. The basic physical regularities of MSU SEP fluxes probabilistic model established 1. The SEP event frequency is proportional to solar activity (SA) 2. The SEP event distribution function is power law with a turn-off at high fluxes (fluences) 3. The SEP event distribution function is invariant relative to SA 4. The SEP energy spectrum at E>30 MeV is power law of the particle momentum per nucleon (rigidity for protons) 5. Some aditional regularities of the SEP particle energy spectra parameters. ISO WG 4, Moscow 2004 R.A.Nymmik

15. The event frequency is proportional to the smoothed sunspot number on the day of the event generation. Dashed line is the dependence, used in JPL-91 model. ISO WG 4, Moscow 2004 R.A.Nymmik The dependence of the SEP event occurrence frequency on the solar activity level

16. circles – the experimental data, circles – the experimental data, and approximations used in: and approximations used in: MSU (solid), MSU (solid), JPL-91 (dashed) and JPL-91 (dashed) and ESP (pointed) models. ESP (pointed) models. ISO WG 4, Moscow 2004 R.A.Nymmik Distribution functions of the SEP events for E30 proton fluences:

17. ISO WG 4, Moscow 2004 R.A.Nymmik Distribution functions for SEP events at SA periods of W 80. Left: the unnormalized functions. Right: the functions, normalized to sum of Wolf numbers in the measurement period

18. The markers denote: METEOR data (circles), GOES data (squares), I MP-8 (black squares), balloon data (triangles), and neutron monitor data (black circles). The energy spectra are shown as power- law functions of momentum (rigidity) (curve 1) and energy (curve 2), rigidity exponent (curve 3). ISO WG 4, Moscow 2004 R.A.Nymmik The integral proton peak fluxes of the 21 May 1990 SEP event.

19. ISO WG 4, Moscow 2004 R.A.Nymmik The dependence of the spectral indexes on the SEP event size Version 3 based on the mixed data of IMP, GOES, Meteor spacecrafts. Version 2004 based on the GOES spacecrafts most reliable (uncorrected) data only

20. ISO WG 4, Moscow 2004 R.A.Nymmik Versions  Фo Фo Фo Фo Previous1.414.510**9 20041.32 9.0 10**9 The distribution functions of MSU model previous and 2004 versions

21. ISO WG 4, Moscow 2004 R.A.Nymmik Model output data requirements The model output data should satisfy the only basic requirement: – they should adequately describe the experimental data on the SEP particle fluxes (and not contradict them), – they should adequately describe the experimental data on the SEP particle fluxes (and not contradict them), corresponding to a space mission with any duration at any level of solar activity

22. ISO WG4, Moscow 2004 R.A.Nymmik MSU Model JPL-91 and ESP MSU Model JPL-91 and ESP models models SEP particles are neglected Solar proton fluences 1994-1997

23. MSU Model JPL-91 and ESP models models SEP particles are neglected Solar proton peak fluxes 1994-1997 ISO WG 4, Moscow 2004 R.A.Nymmik

24. Annual solar proton fluence spectra for years with 100<W<150 MSU Model JPL-91 model MSU Model JPL-91 model

25. ISO WG 4, Moscow 2004 R.A.Nymmik 22 and 23 SA cycle data and model outputs MSU Model JPL-91 model

26. ISO WG 4, Moscow 2004 R.A.Nymmik 22 and 23 SA cycle data and model outputs MSU model The King, JPL-91 and JPL-91 improved in SPENVIS

27. ISO WG 4, Moscow 2004 R.A.Nymmik Solar proton annual peak fluxes for years with SA 100<W<150 Experimental data for years: 1989, 2000 and 2003 are demonstrated. MSU model outputs are valid from 4 to 10000 MeV There are published data in the ESP model for 10 MeV only

28. ISO WG 4, Moscow 2004 R.A.Nymmik As it is seen from above, the MSU SEP flux model (proton fluences and peak flux) reliably describes the experimental data for: any solar activity conditions and As it is seen from above, the MSU SEP flux model (proton fluences and peak flux) reliably describes the experimental data for: any solar activity conditions and any space mission duration any space mission duration for proton energies ≥4 MeV (high energies are not limited). for proton energies ≥4 MeV (high energies are not limited). In our opinion In our opinion such efficiency of the semi-empirical model is achieved primarily due to the account for fundamental regularities inherent to solar energetic particle events and fluxes and cannot be achieved by the empirical methodology, used in the development of JPL-91 and ESP models. such efficiency of the semi-empirical model is achieved primarily due to the account for fundamental regularities inherent to solar energetic particle events and fluxes and cannot be achieved by the empirical methodology, used in the development of JPL-91 and ESP models.

29. The calculations by the model are available for everybody on the Web-site: On this Web-site you can read also the On this Web-site you can read also the Technical Specification Technical Specification and the Memorandum (90 pages). and the Memorandum (90 pages). All this documents are sent to the ISO WG-4 referents (see the resolution No 166) All this documents are sent to the ISO WG-4 referents (see the resolution No 166) http/srd.sinp.msu.ru/models/sep2004.html

30. ISO WG 4, Moscow 2004 R.A.Nymmik This version of the ISO Technical Specification is prepared according to the International Standard Organization Technical Committee 20 (Aircraft and space vehicles), Subcommittee SC 14, (Space systems and operations) Working Group 4 (Space Environment) 18th - meeting (Toulouse, France, September, 2003) resolution No 166. This version of the ISO Technical Specification is prepared according to the International Standard Organization Technical Committee 20 (Aircraft and space vehicles), Subcommittee SC 14, (Space systems and operations) Working Group 4 (Space Environment) 18th - meeting (Toulouse, France, September, 2003) resolution No 166. The work was supported by INTAS grant No. 00-629.