Eduard V. VASHENYUK, Yuri V. BALABIN, Boris B. GVOZDEVSKY

1. High Energy Solar Cosmic Ray Phenomena during SEE of 2003 Eduard V. VASHENYUK, Yuri V. BALABIN, Boris B. GVOZDEVSKY Polar Geophysical Institute, Apatity, 184209 Russia Leonty L.MIROSHNICHENKO IZMIRAN Troitsk, Moscow region, 141090 Russia

2. The primary relativistic solar proton (RSP) parameters during the • ground level enhancements (GLE) of SEE in the autumn of 2003 • October 28 and November 2 have been obtained by modeling of • the responses of neutron monitors of the worldwide network and • comparing them with observations. The modeling comprised an • optimization procedure as well as proton trajectory calculations • in the up-to-date magnetosphere model Tsyganenko-2002 (T01) • The spectra, pitch-angle distributions and anisotropy of RSP • obtained for successive moments of time allowed to study the • dynamical changes of these parameters during the events. Two • populations of RSP: prompt and delayed one revealed from rigidity • (energetic) spectra dynamics and pitch angle distributions are discussed. • OUTLINE: • 1. Short information about GLE’s under study • 2. Details of GLE modeling technique and deriving • relativistic solar proton (RSP) parameters from ground • based observations • 3 RSP derived parameters analysis and study of their dynamics • 4. Discussion&Conclusions

4. GLEs occurred during the 2003 SEE

5. North-South relativistic solar proton anisotropy, SEE 2003 McM McMurdo, Antarctica, Ba -Barentsburg, Spitsbergen

6. GLE Modeling Technique. Definition of primary solar proton parameters from neutron monitor observations • Modeling technique of the neutron monitor response to an anisotropic • solar proton flux (Shea & Smart, 1982, Cramp et al., 1997, Vashenyuk et al., 2003) • consisted of a few steps: • Definition of asymptotic viewing cones of neutron monitor stations • under study by the particle trajectory computations in a model • magnetosphere (step in rigidity 0.001 GV). The magnetosphere • model T01 (Tsyganenko, 2002) and T01s (Tsyganenko, 2003) were • employed. • Calculation of neutron monitor responses at variable primary solar • proton flux parameters • Determination by a least square procedure (optimization) primary • solar proton parameters outside magnetosphere by comparison of • calculated neutron monitor responses with observations.

7. Details of modeling technique • The response function of a neutronmonitor to anisotropic flux of solar protons (Shea & Smart, 1982, • Vashenyuk et al., 2003) • 20GV • (N / N) j = ΣJ(R)S(R)F (j (R))A(R) d R(1 ) • Rc • Where (dN/N)J is percentage increase effect at a given neutron monitor j • J(R) = JoR-*is rigidity spectrum of RSP flux in the direction of anisotropy axis • * = + ·R where  is increase per 1 GV (Cramp et al., 1997) • S(R) is specific yield function (Debrunner et al., 1984), • θ(R) is pitch angle (angle between the anisotropy axis and an asymptotic direction at a given rigidity R) • A(R) = 1 for allowed and 0 for forbidden trajectories • F(θ(R ))~ exp(-θ2/C)is pitch-angle distribution of RSP (Shea&Smart, 1982) • So 6 parameters of anisotropic solar proton flux outside magnetosphere: • ; , Jo, , , C are to be determined by a least square procedure (Dennis and Schnabel, 1983) : • SN = Σ ( (N / N)j calc - (N / N)jobserv )2 min (2) • j

8. In general case a model with two independent particle fluxes from opposite directions is employed with independent set of paqrameters: • 20GV • (N / N)j = Σ(P1j Aj(R) + P2j Aj(R))d R (3) • Rc • whereP1j = J1(R) S(R) F1 ( j(R)) , P2 = J2(R)S(R)F2 (j (R)); • J1(R), J2(R) are spectralfunctions of both particle fluxes • F1 (j(R)), F2 (j (R))are their pitch angle distribution functions

9. Examples of neutron monitor response modeling November 2, 2003 GLE

10. Derived RSP parameters for the 28.10.2003 GLE direct flux from the sun Time γ α c θ φ J0 1140 -0.84 0.91 0.28 -1.05 -1.82 2970 1145 -4.48 0.0 0.25 -1.02 -1.97 31600 1150 -4.39 0.0 0.24 -1.03 -1.87 33100 1155 -3.93 0.0 0.23 -1.10 -1.79 22200 1200 -1.54 0.13 0.23 -1.16 -1.94 3300 1210 -4.38 0.0 0.44 -1.12 -2.22 33300 Time γ α C θ φ J0 1140 -0.79 0.25 10.27 1.05 1.27 247 1145 -3.90 0.05 7.57 1.02 1.20 15200 1150 -1.49 0.28 7.41 1.03 1.30 3600 1155 -0.72 0.54 11.82 1.10 1.39 1450 1200 -1.72 0.22 16.75 1.16 1.14 5300 1210 -5.60 0.003 5.36 1.12 1.00 56400 reverse flux from the antisun direction

11. asymptotic viewing cones of a number neutron monitor stations: GLE profiles at a number of neutron monitor stations

13. 2.11.2003GLE Derived pitch angle distribution and its evolution

14. GLE of 28.10.2003 increase profiles at different neutron monitor stations. Note the impulselike increase at Norilsk and Moscow

15. asymptotic viewing cones of a number neutron monitor stations:

16. Derived solar proton spectra. By red is shown the spectrum of the RSP prompt component

17. Derived pitch- angle distribution for the initial pulse

18. Pitch-angle evolution in the supercoherent bunch of the 5 MeV solar proton propagating in the IMF

19. Рис. 37. Искривление и усиление межпланетного магнитного поля на быстром сверхмагнитовуковом облаке, движущемся вправо вдоль горизонтальной оси. Усиление может составить до 5-6 раз, то есть,. если внешнее невозмущенное поле было ~5-10 нТ, то на флангах облака возмущенное поле может достигать ~25-60нТл, что вполне достаточно для генерации сильной геомагнитной бури.

20. Fig5 Derived pitch-angle distributions for the delayed particle population. Note the backward flux appeared after 12.10 UT

21. On the solar neutrons detection by the NM Tsumeb

22. Sun elevation Angle, degrees Moscow 57 N 37 E 16 Norilsk 69 N 88 E -8 Erevan 44 N 40 E 29 Jungfrau 45 N 8 E 31 Tsumeb 20 S 18 E 80

23. Discussion / Conclusions • The modeling study of the 28 October and 2 November GLEs using the data of the worldwide neutron monitor network has been performed to obtain parameters of relativistic solar protons and analysis of their dynamics. • The steady north-south anisotropy of relativistic solar cosmic rays was observed which remained through the period of 28.10-3.11. Obviously this anisotropy also detected by the CORONAS F satellite was a manifestation of the superlarge-scale distortion in the IMF structure. IMF was distorted also in the azimuth as is indicated by the RSP and GCR anisotropy. • Bidirectional anisotropy at late phase of the 28.10 GLE may be related to the looplike IMF structure inside the flare ejecta causing a forbush effect. • The common feature of the considered events is existence of two populations (components) of relativistic solar protons(RSP): prompt (PC) and delayed (DC). The PC has an impulselike intensity profile, hard (exponential) energetic spectrum. These specify a localized source of prompt acceleration in the corona, which can be an impulsive acceleration by an electric field in reconnecting current sheets (Perez-Peraza et al., 1992, Miroshnichenko et al., 1993, I.Podgorny, A.Podgorny, 2002). An exponentialform of energetic spectrum is characteristic for such kind of acceleration (Bulanov &Sasorov, 1975, Vashenyuk et al., 2003, Balabin et al., 2004).

24. The maximum of DC was observed 20-30 min after the peak of PC • and had the steeper energetic spectrum and a wide pitch-angle distribution. A • possible source of the delayed population of RSP in the corona can be a CME • driven shock or a stohastic acceleration by a strong MHD turbulence • Solar neutron event seem to be detected by the NM Tsumeb, South • Afrika.The ground base increase coincided in time with detecting solar • neutrons by SONG instrument at CORONAS F s/c.