The method for predicting solar proton events

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    O. B

    ed f

    gates hnerthe(fr

    2008 COSPAR. Published by Elsevier Ltd. All rights reserved.

    problem had been solved, diculties would have arisen inpredicting ux localization of accelerated particles in the

    netic elds and active photospheric and chromospheric for-mations. These formations can be dened from directmagnetic-eld measurements in the photosphere or from

    advance time of about 1 h. The rst method is suitable onlyfor the GLE registration, as registration frequency of GLE

    tics is performed in the interplanetary magnetic-eld (IMF)lines that now connect the Earth with correspondingregions on the Sun. Articles Volodichev et al. (1985) andDvornikov et al. (1984, 1988) prove the existence of suchsituations. The purpose of this article is to realize such apossibility.

    * Corresponding author.E-mail address: (V.M. Dvornikov).

    Available online at

    Advances in Space Research 4interplanetary space, and in predicting their arrival at theEarth. There are some organizations engaged in a short-term prediction of solar ares. The leading among themis the Prognosis Centre that is a division of the Space Envi-ronment Centre and is under the joint guidance of theNational Oceanic and Atmospheric Administration(NOAA) and the US air forces. Prognosis methods usedare based on data about structure and dynamics of mag-

    is less than that of high-energy SCR.We can solve SPE prediction problem with an accept-

    able advance time and conrmation degree, only if the areenergy accumulation is the result of dynamics of currentsystems localized in the solar corona and stretched up tosome distances in the heliosphere. In this case an attemptto nd SPE predictors using the heliosphere diagnosticsfrom cosmic-ray (CR) eects is worthwhile. Such diagnos-Keywords: Solar proton events; Solar proton prediction; Heliospheric electromagnetic characteristics; Solar magnetic elds

    1. Introduction

    Predicting of solar proton events (SPEs) is associatedwith various complicated circumstances, the most impor-tant of which is the absence of theoretically proved algo-rithms for solving the given problem. Thus we can notdetermine necessary and sucient predictors for identica-tion of pre-are situation on the Sun. However, if this

    indirect methods with the use of Sun images in chromo-spheric and coronal spectral lines made by ground-basedand satellite instruments.

    There is a prognosis method for low-energy protonuxes from behaviour of high-energy particle intensity atthe initial increase stage (at SCR ground level enhancement(GLE), Dorman et al., 2004) and of high-energy electrons( with predictionThe method for predic

    V.M. Dvornikov *, M.V. Kravtsov

    Institute of Solar-Terrestrial Physics SB RAS, Irkutsk P.

    Received 23 February 2008; received in revis


    Dynamic processes in the interplanetary space have been investiity spectrum. Change of heliosphere electromagnetic characteristicparticular, it is shown that sporadic phenomena are followed by geeld strength in small-scale heliospheric structures, and increase ofThese features allow prediction of solar proton events in advanceconrmation.0273-1177/$34.00 2008 COSPAR. Published by Elsevier Ltd. All rights resedoi:10.1016/j.asr.2008.10.028g solar proton events

    A.A. Lukovnikova, V.E. Sdobnov

    ox 291, Lermontov Street, 126a, 664033 Irkutsk, Russia

    orm 13 May 2008; accepted 8 October 2008

    d using time variations in time parameters of the cosmic-ray rigid-as been found out to precede sporadic phenomena on the Sun. Ination of local polarization electric elds, decrease of the magnetic-potential dierence between the pole and the plane of the several hours to several tens of hours) with a high degree of

    3 (2009) 735738rved.

  • of particle energy variations over energy ranges

    n Sp2. Data and method

    We used mid-hour observation data of proton intensitywithin energy ranges of 49, 915, 1540, 4080, 80165,165500 MeV registered at the satellite GOES-10 ( for analysis. We alsoused data on intensity variations of various-rigidity CRobtained by the spectrographic global survey (SGS)method (Dvornikov and Sdobnov, 1997) from ground-based measurements at the world network of neutron mon-itors (38 stations).

    The expression from Volodichev et al. (1985) was usedfor description of the CR rigidity spectrum over a wideenergy range.

    JR A e2 e20

    e De2 e20

    " #3=2

    e Dee

    2e De2 e20


    e2 e20

    pe2 e20p



    ; 1

    where e is the total particle energy; e0 is the rest energy, Aand c are spectral indices of galactic spectrum; De are par-ticle energy variations in the heliosphere electromagneticelds specied by the expression:

    DeR De0 De11 f R; b R0 De21 f R; b R0f R;R0 e1 ea=2 e

    be2 e20 e20

    qf R;R0: 2

    The expression (1) was derived from the Liouville theo-rem on the assumption that the energy range observed hasno solar particle source (SCR). The expression (2) wasderived from the general solution of particle motion equa-tion in the drift approximation (Dvornikov et al., 2005a)on the assumption that polarization and vortex electricalelds might be generated in the heliosphere along with aninduced electric eld. Generation of polarization electricalelds may result from distribution of beam particles, accel-erated on the Sun, in inhomogeneous magnetic eldsbecause of protons and electrons drifting in opposite direc-tions. This may lead to charge separation and potential dif-ference between beam boundaries along magnetic drifttrajectories, if spatial inhomogeneity of accelerated parti-cles is observed. This fact in its turn results in generationof polarization electrical eld increasing with time andpolarization drift of plasma background particles of thesolar wind, solar coronas and galactic cosmic rays alongthis eld. Thus we observe particle acceleration of the solarcorona and interplanetary medium with their Larmor radiiless than the across size of the given beam. Appearance ofdepolarizing longitudinal currents leads to current systemformation, generation of magnetic eld and vortex electri-cal eld, which accelerates particles due to the betatronic

    736 V.M. Dvornikov et al. / Advances imechanism, etc. L. Lindbergs Alfven (1981) laboratoryexperiments proved generation of such elds.[0.108,R0], [R0,R0 + b] and [R0 + b, 1] GV, where b = 5GV. These functions tend to 1 at R < R0 or R < b + R0and to 0 at R > R0 or R > b + R0. Expression for thequasi-step function, its parameters and the constant De0including the residual modulation for low-energy particleshave been found empirically in Dvornikov et al. (2005b).

    Thus we can monitor heliosphere electromagneticcharacteristics and their dynamics via the determinationof dierential CR rigidity spectrum parameters with theuse of the Eq. (1) solution in view of (2) according to mea-suring data on particle intensity in given energy ranges pereach observation hour. Monitoring of the interplanetarymedium during the period of OctoberNovember 2003and in 2004 was carried out with this method.

    3. Analysis of results

    Triangles in three upper panels of Fig. 1 demonstrateobservation data on proton intensities within energyranges 49 MeV (0.108 GV), 915 MeV (0.223 GV) and5 GV; solid curves present calculation results made withthe use of model spectrum and obtained values of itsparameters. Dst-index values are presented in the fourthpanel. Mid-hour values of rigidity spectrum parametersDe1, a, b, and R0 are presented in four lower panels.These parameters have been determined during the per-iod under study.

    Comparison of temporal variations of CR rigidityspectrum parameters with temporal intensity proles oflow-energy CR (the rst two panels of Fig. 1) implies thatchanges in heliosphere electromagnetic characteristicsoccur on the day before solar proton events. In particular,generation of local polarization electric elds (increase ofthe parameter a) takes place several hours or tens of hoursSpectrum parameters De1, De2, a, b, and R0 present thefollowing heliosphere characteristics: R0 is the parameterdescribing the structural formation scale in the heliospherewith non-stationary electromagnetic elds; De1 determinesCR energy variations caused by gradient and centrifugalparticle drifts in the spiral interplanetary magnetic eld(IMF) in the direction opposite to the induced electric eld,and it is proportional to the IMF intensity; De2 denes suchvariations in the elds of coronal mass ejections (CME)and is proportional to the magnetic-eld intensity inCME and to the solar wind (SW) velocity (Dvornikovand Sdobnov, 2002). The parameter b equals B/B0, whereB0 is the background eld intensity, and B is the time-var-iable IMF intensity; the parameter describes inuence ofnon-stationary magnetic elds on the CR spectrum (withmagnetic rigidity of particles R 6 R0); the parametera = Epl

    2/B2 characterizes inuence of polarization electricelds Epl. Quasi-step functions f(R,R0), f(R,b + R0) areintroduced to lend importance to this or that mechanism

    ace Research 43 (2009) 735738before SPE. During this period, we also observe decrease inthe magnetic-eld strength in small-scale structures of the

  • n Sp0.108 GV102




    0.223 GV





    1.10-5s (cm

    2 s

    sr V


    V.M. Dvornikov et al. / Advances iheliosphere (decrease of the parameter b), and increase inthe large-scale spiral IMF strength (parameter De1).

    This fact permits us to predict SPE using monitoring ofheliosphere electromagnetic characteristics (in the real-tim