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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. INTERNATIONAL STANDARDIZATION ORGANIZATION TECHNICAL SPECIFICATION 15391.

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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

INTERNATIONAL STANDARDIZATION ORGANIZATIONTECHNICAL SPECIFICATION 15391
iso wg 4 moscow 2004 r a nymmik
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.

iso wg 4 moscow 2004

R.A.Nymmik

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.

iso wg 4 moscow 20044

R.A.Nymmik

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:

iso wg 4 moscow 2004 r a nymmik5
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 spacecraftsversus energy

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ISO WG 4, Moscow 2004 R.A.Nymmik

An example of systematic errors in the measurement results

The distribution of peak flux ratios for the SEP events,recorded by GOES-6 and GOES-7 measurement channels.

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ISO WG 4, Moscow 2004 R.A.Nymmik

The channel 10 of CPME insrument on IMP-8

An example of systematic errors in the measurement results

iso wg 4 moscow 20048

R.A.Nymmik

ISO WG 4, Moscow 2004

An example of systematic errors in the measurement results

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

iso wg 4 moscow 20049

R.A.Nymmik

ISO WG 4, Moscow 2004

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)

iso wg 4 moscow 200410

R.A.Nymmik

ISO WG 4, Moscow 2004

Main errors of the

  • JPL-91 (Feynman et al.) and
  • 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

iso wg 4 moscow 2004 r a nymmik11
ISO WG 4, Moscow 2004 R.A.Nymmik

Neglecting the SEP fluxes in the “Quiet”

Sun period (W<40)

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.

iso wg 4 moscow 2004 r a nymmik12
ISO WG 4, Moscow 2004 R.A.Nymmik

Assumption that SEP event frequency and

flux sizes are the same for the whole

“Active” Sun (W>40)period

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!

iso wg 4 moscow 2004 r a nymmik13
ISO WG 4, Moscow 2004 R.A.Nymmik

Another methodological shortcomings of the JPL-91 and ESP models are:

  • the nonphysical (“engineering” or “commercial”) definition of the “SEP event”,
  • use of partially unreliable databases
  • 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.
slide14

ISO WG 4, Moscow 2004 R.A.Nymmik

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.

slide15

ISO WG 4, Moscow 2004 R.A.Nymmik

The dependence of the SEP event occurrence frequency on the solar activity level

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.

slide16

ISO WG 4, Moscow 2004 R.A.Nymmik

Distribution functions of the SEP events

for E30 proton fluences:

  • circles – the experimental data,
  • and approximations used in:
  • MSU(solid),
  • JPL-91 (dashed) and
  • ESP (pointed) models.
slide17

ISO WG 4, Moscow 2004 R.A.Nymmik

Distribution functions for SEP events at SA periods of W<80 and W>80.

Left: the unnormalized functions. Right: the functions, normalized to sum of Wolf numbers

in the measurement period

slide18

ISO WG 4, Moscow 2004 R.A.Nymmik

The integral proton peak fluxes of the 21 May 1990 SEP event.

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).

slide19

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

iso wg 4 moscow 2004 r a nymmik20
ISO WG 4, Moscow 2004 R.A.Nymmik

The distribution functions of MSU modelprevious and 2004 versions

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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),

corresponding to a space mission with any duration

at any level of solar activity

iso wg4 moscow 2004 r a nymmik
ISO WG4, Moscow 2004 R.A.Nymmik

Solar proton fluences 1994-1997

  • MSU ModelJPL-91 and ESP

models

SEP particles are neglected

slide23

ISO WG 4, Moscow 2004 R.A.Nymmik

Solar proton peak fluxes 1994-1997

MSU ModelJPL-91 and ESP

models

SEP particles are neglected

iso wg 4 moscow 2004 r a nymmik24
ISO WG 4, Moscow 2004 R.A.Nymmik

Annual solar proton fluence spectra for years with 100<W<150

MSU ModelJPL-91 model

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ISO WG 4, Moscow 2004 R.A.Nymmik

22 and 23 SA cycle data and model outputs

MSU ModelJPL-91 model

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ISO WG 4, Moscow 2004 R.A.Nymmik

22 and 23 SA cycle data and model outputs

MSU modelThe King, JPL-91

and JPL-91 improved

in SPENVIS

iso wg 4 moscow 2004 r a nymmik27
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 2003are demonstrated.

MSU model outputs are valid from 4 to 10000 MeV

There are published data in the ESP model for 10 MeV only

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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
  • any space mission duration
  • for proton energies ≥4 MeV(high energies are not limited).
  • In our opinion
  • such efficiency of the semi-empirical model is achieved primarily due to the account forfundamental 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.
the calculations by the model are available for everybody on the web site
The calculations by the model are available for everybody on the Web-site:
  • On this Web-site you can read also the
  • Technical Specification
  • and the Memorandum (90 pages).
  • All this documents are sent to the ISO WG-4 referents (see the resolution No 166)

http/srd.sinp.msu.ru/models/sep2004.html

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ISO WG 4, Moscow 2004 R.A.Nymmik

This version of the ISO Technical Specification is prepared according to the International Standard OrganizationTechnical 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.