Models of solar energetic particle fluxes- the main requirements and development prospects

航天,航天器,航天器环境,空间辐射

AdvancesinSpaceResearch36(2005)

2003–2011

/locate/asr

Modelsofsolarenergeticparticle uxes:Themainrequirements

andthedevelopmentprospects

N.V.Kuznetsov,R.A.Nymmik*,M.I.Panasyuk

SkobeltsynInstituteofNuclearPhysics,MoscowStateUniversity,VorobjovyGory,Moscow119992,Russia

Received19October2002;receivedinrevisedform5May2003;accepted27September2004

Abstract

Themodelsofsolarenergeticparticles(SEP)areintendedforcalculatingtheproton uencesandpeak uxes,whichareexpectedtooccurforagivenperiodatanyknownorpredictedsolaractivitylevelandtoexceedtheircalculatedsizeswithinagivenprob-ability.AnySEPmodelshouldre ecttheobjectivereality,includingtheregularfeaturesinherenttotheparticles.Therequirementsareformulated,whichhavetobemetbythepresent-daymodelsaimedatpredictingtheSEP uxesinthespacecrafttrajectoriesasaccuratelyaspossible.Particularattentionispaidtoanalyzingthefactorsthatcausethemostfrequentde cienciesofthepresent-daysolarenergeticparticle uxmodels.

Ó2005COSPAR.PublishedbyElsevierLtd.Allrightsreserved.

Keywords:Solarenergeticparticles;SEP uxmodels;Modelrequirements;Modeldevelopmentprospects

1.Introduction

Thesolarenergeticparticle(SEP)models,likeanymodelthatdescribesthenaturalphenomenon,shouldre ecttheobjectivereality,includingtheregularfea-turesinherenttothereality.Themodelsmustbedevel-oped,ifpossible,intermsoftheconceptsandbehavioralfeaturesthatareclosetothephysicalessenceofamod-elednaturalphenomenon.

Thisprerequisiteimpliesthat: sincetheSEP uxoccurrenceintheEarthÕsorbitisassociatedwithaparticulareventofparticlegenera-tionandejectioninthesolarchromosphere,eachoftheoccurrences(calledaSEPevent)mustberegardedasresultingfromacertainsingleeventthatoriginatesontheSun;

*

Correspondingauthor.Tel.:+7959328861;fax:+7959395034.E-mailaddress:nymmik@sinp.msu.ru(R.A.Nymmik).

sincetheSEPeventoccurrenceprobabilitydependsonsolaractivity,themodelsmustpredicttheSEP uxesasdependentonanysolaractivitylevel.ThedependenceofSEPeventoccurrencefrequencyonsolaractivityisasmoothcontinuousfunction;theexperimentaldataindicateneitherathresholde ect,noranabruptjumplikevariation,noraplateau;

sincetheSEPdistributionfunctionbelongstotherangeofthedistributionfunctionsofothersolarimpulseevents(theradio(Fitzerreiteretal.,1976),X-ray(Crosbyetal.,1993),andgamma-ray(Luetal.,1993) ares),whichhavebeenproperlystudiedandarepower-lawfunctions,itisquiteobvioustoassumethattheSEPdistributionisalsodescribedbyapower-lawfunction.Becauseofthelimitedsolarenergetics,thepower-lawdistributionfunctionscan-notextenduptoin nityasthesolarimpulseevent(includingSEPevents)sizeincreases,butmustsu eraturno ,whichisjustobservedactually(Luetal.,1993;Xapsosetal.,1998,1999;Nymmik,1999a);

0273-1177/$30Ó2005COSPAR.PublishedbyElsevierLtd.Allrightsreserved.doi:10.1016/j.asr.2004.09.021