international standardization organization technical specification 15391 space environment (natural...

INTERNATIONAL STANDARDIZATION ORGANIZATIONINTERNATIONAL STANDARDIZATION ORGANIZATIONTECHNICAL SPECIFICATION 15391TECHNICAL SPECIFICATION 15391

Space Environment Space Environment

(Natural and Artificial)(Natural and Artificial)Probabilistic model of fluences and peak Probabilistic model of fluences and peak

fluxes of solar energetic particlesfluxes of solar energetic particles

Part I ProtonsPart I Protons

(Version 2004)(Version 2004)

by by R.A. Nymmik R.A. Nymmik

ISO WG 4, Moscow 2004 ISO WG 4, Moscow 2004 R.A.NymmikR.A.Nymmik

The present Standard is intended for calculating The present Standard is intended for calculating the fluences and peak fluxes of solar energetic the fluences and peak fluxes of solar energetic protons, which are expected to occur during a protons, which are expected to occur during a given time interval at any known or predicted given time interval at any known or predicted

solar activity level and to exceed their calculated solar activity level and to exceed their calculated sizes with a given probability. sizes with a given probability.

In combination with the ISO 15390 Standard – In combination with the ISO 15390 Standard – Model of Galactic Cosmic rays, this Standard Model of Galactic Cosmic rays, this Standard

provides a description of the radiation provides a description of the radiation environment, induced by high-energy particle environment, induced by high-energy particle

fluxes on the Earth’s orbit in interplanetary space fluxes on the Earth’s orbit in interplanetary space and serves as the basis for describing the and serves as the basis for describing the

radiation environment during interplanetary radiation environment during interplanetary missions, and for calculating particle fluxes, missions, and for calculating particle fluxes,

penetrating into near-Earth spacecraft and space penetrating into near-Earth spacecraft and space station orbits. station orbits.

ISO WG 4, Moscow 2004ISO WG 4, Moscow 2004

SEP flux model - version 2004 SEP flux model - version 2004 is the MSU model,is the MSU model,

corrected according to the results corrected according to the results of study of the systematical of study of the systematical errors and reliability of the errors and reliability of the

different Solar Energetic protons different Solar Energetic protons flux data, measured on different flux data, measured on different

spacecrafts by different spacecrafts by different instruments.instruments.

R.A.NymmikR.A.Nymmik


Some examples of systematic errors in Some examples of systematic errors in the measurement resultsthe measurement results

A convenient technique of multiple A convenient technique of multiple analysis of SEP events fluxes and analysis of SEP events fluxes and energy spectra is the logarithmic energy spectra is the logarithmic

mean of a set of events:mean of a set of events:


n

ii EF

nEF 1

lg1

10


An example of systematic errors in the An example of systematic errors in the measurement resultsmeasurement results

The ratio of the sizes of

the SEP events peak

fluxes , measured on

the IMP-8 and GOES-7 spacecrafts

versus energy

ISO WG 4, Moscow 2004 R.A.NymmikISO 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 resultsAn example of systematic errors in the measurement results

The channel 10 of CPME insrument on The channel 10 of CPME insrument on IMP-8IMP-8


The distribution The distribution functions for the functions for the SEP events which SEP events which occurred during occurred during 1986-2002 1986-2002 according to IMP-according to IMP-8 and GOES-7&8 8 and GOES-7&8 spacecrafts spacecrafts measurements of measurements of EE30 and E30 and E300 300 MeV proton MeV proton fluxes and their fluxes and their approximationsapproximations




..


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-82. GOES-7 (corrected)


Main errors of theMain errors of the JPL-91JPL-91 (Feynman et al.) and (Feynman et al.) and ESPESP (Xapsos et al.) models (Xapsos et al.) models1. Neglecting the SEP fluxes in the 1. Neglecting the SEP fluxes in the

“Quiet” Sun“Quiet” Sun period (W<40) period (W<40)

2. Assumption that SEP event 2. Assumption that SEP event frequency and flux sizes are the frequency and flux sizes are the same for the whole same for the whole “Active” “Active” SunSun (W>40)period (W>40)period



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” Neglecting the SEP fluxes in the “Quiet” Sun period (W<40)Sun period (W<40)


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 andAssumption 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)periodActive” Sun (W>40)period


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

The basic The basic physical regularitiesphysical regularities of MSU of MSU SEP fluxes probabilistic model SEP fluxes probabilistic model

establishedestablished1. The SEP event frequency is proportional to 1. The SEP event frequency is proportional to

solar activity (SA)solar activity (SA)

2. The SEP event distribution function is power 2. The SEP event distribution function is power law with a turn-off at high fluxes (fluences)law with a turn-off at high fluxes (fluences)

3. The SEP event distribution function is 3. The SEP event distribution function is invariant relative to SAinvariant relative to SA

4. The SEP energy spectrum at E>30 MeV is 4. The SEP energy spectrum at E>30 MeV is power law of the particle momentum per power law of the particle momentum per nucleon (rigidity for protons)nucleon (rigidity for protons)

5. Some aditional regularities of the SEP 5. Some aditional regularities of the SEP particle energy spectra parameters.particle energy spectra parameters.


The event The event frequency is frequency is

proportional to proportional to the smoothed the smoothed

sunspot number sunspot number on the day of on the day of

the event the event generation.generation.

Dashed line is Dashed line is the the

dependence, dependence, used in JPL-91 used in JPL-91

modelmodel..


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

levellevel

circles circles – the – the experimental experimental data, data,

and and approximations approximations used in: used in:

MSUMSU (solid), (solid), JPL-91JPL-91 (dashed) (dashed)

and and ESP ESP (pointed) (pointed)

modelsmodels..


Distribution functions of the SEP events Distribution functions of the SEP events for Efor E30 proton fluences:30 proton fluences:


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

The markers denote: The markers denote: METEOR METEOR data data

(circles), (circles), GOES GOES data data (squares), (squares), II

MP-8MP-8 (black squares), (black squares), balloon balloon data data

(triangles), and (triangles), and neutron monitorneutron monitor data data

(black circles). (black circles). The energy spectra The energy spectra

are shown as are shown as power-power-law functions of law functions of

momentummomentum (rigidity) (rigidity) (curve 1) and (curve 1) and energy energy

(curve 2), (curve 2), rigidity rigidity exponentexponent (curve 3). (curve 3).


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


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


VersionsVersions ФФoo

PreviousPrevious 1.411.41 4.54.5

10**910**9

20042004 1.321.32 9.09.010**910**9

The distribution functions of MSU model previous and 2004 versions

o

30exp

)(


Model output data requirementsModel output data requirements

The model output data should satisfy The model output data should satisfy the only basic requirement:the only basic requirement:

– – they should adequately describe the they should adequately describe the experimental data on the SEP particle experimental data on the SEP particle

fluxes (and not contradict them), fluxes (and not contradict them),

corresponding to a space mission with corresponding to a space mission with any durationany duration

at any level of solar activityat any level of solar activity

ISO WG4, Moscow 2004 R.A.NymmikISO WG4, Moscow 2004 R.A.Nymmik

MSU ModelMSU Model JPL-91 and ESPJPL-91 and ESP modelsmodels

SEP particles

are neglected

Solar proton fluences 1994-1997

MSU ModelMSU Model JPL-91 and ESPJPL-91 and ESP modelsmodels

SEP particles

are neglecte

d

Solar proton peak fluxes 1994-1997



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

MSU ModelMSU Model JPL-91 modelJPL-91 model


22 and 23 SA cycle data and model outputs

MSU ModelMSU Model JPL-91 modelJPL-91 model


22 and 23 SA cycle data and model outputs

MSU model The King, JPL-91 and JPL-91 improved in SPENVIS


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 MeVThere are

published data in the ESP

model for 10 MeV only


As it is seen from above, the MSU SEP flux As it is seen from above, the MSU SEP flux model (proton fluences and peak flux) model (proton fluences and peak flux) reliably describes the experimental data reliably describes the experimental data for:for: any solar activity conditions and any solar activity conditions and

any space mission durationany space mission duration for proton energies ≥4 MeVfor proton energies ≥4 MeV (high energies (high energies

are not limited).are not limited). In our opinionIn our opinion such efficiency of the semi-empirical model such efficiency of the semi-empirical model

is achieved primarily due to the account foris achieved primarily due to the account for fundamental regularities inherent to solar fundamental regularities inherent to solar energetic particle events and fluxesenergetic particle events and fluxes and and cannot be achieved by the empirical cannot be achieved by the empirical methodology,methodology, used in the development of used in the development of JPL-91 and ESP models.JPL-91 and ESP models.

The calculations by the model are The calculations by the model are available for everybody on the Web-site: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 SpecificationTechnical Specification andand the Memorandum (90 pages). the Memorandum (90 pages). All this documents are sent to the ISO All this documents are sent to the ISO

WG-4 referents WG-4 referents (see the resolution(see the resolution No No 166)166)

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


This version of the This version of the ISO Technical ISO Technical SpecificationSpecification is prepared according to the is prepared according to the International Standard OrganizationInternational Standard Organization Technical Committee 20 (Aircraft and Technical Committee 20 (Aircraft and space vehicles), Subcommittee SC 14, space vehicles), Subcommittee SC 14, (Space systems and operations) Working (Space systems and operations) Working Group 4 (Space Environment) Group 4 (Space Environment) 18th18th - - meeting meeting (Toulouse, France, September, (Toulouse, France, September, 2003) 2003) resolutionresolution No 166 No 166. .

The work was supported by INTAS grant No. The work was supported by INTAS grant No. 00-629.00-629.

international standardization organization technical specification 15391 space environment (natural...

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