Irkutsk, Russian Federation
Irkutsk, Russian Federation
Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.
cosmic rays, ground level enhancement, anisotropy, rigidity spectrum
1. Bazilevskaya G.A., Svirzhevskaya A.K., Sladkova A.I. Relation between solar proton events and X flares of different classes. Geomagnetism and Aeronomy. 2004, vol. 44, no. 4, pp. 404-409.
2. Belov A.V., Eroshenko E.A., Vashenyuk E.V., Pchelkin V.V. Cosmic-ray intensity enhancement and structure of the 1998 May 2 solar wind disturbance. Solar System Res. 2000, vol. 34, no. 2, pp. 154-157.
3. Belov A.V., Eroshenko E.A., Kryakunova O.N., Kurt V.G., Yanke V.G. Ground Level Enhancements of solar cosmic rays during the last three solar cycles. Geomagnetism and Aeronomy. 2010, vol. 50, no. 1, pp. 21-33.
4. Belov A., Garcia H., Kurt V., Mavromichalaki H., Gerontidou M. Proton enhancements and their relation to the X-ray flares during the three last solar cycles. Solar Phys. 2005, vol. 229, pp. 135-159. DOI:https://doi.org/10.1007/s11207-005-4721-3.
5. Cliver E.W. The Unusual Relativistic Solar Proton Events of 1979 August 21 and 1981 May 10. Astrophys. J. 2006, vol. 639, no. 2, pp. 1206-1217. DOI:https://doi.org/10.1086/499765.
6. Danilova O.A., Tyasto M.I., Vashenyuk E.V., et al. The GLE of May 2, 1998: an effect of disturbed magnetosphere on solar cosmic rays. Proc. 26th Int. Cosmic Ray Conf. Salt Lake City, USA, 1999, vol. 6, pp. 399-402.
7. Danilova O.A., Tyasto M.I., Vashenyuk E.V., Gvozdevsky B.B., Kananen H., Tanskanen P. Magnetosheric response to the Ground Level Enhancement of solar cosmic rays on May 2, 1998. Geomagnetism and Aeronomy. 2002, vol. 42, no. 1, pp. 28-31.
8. Dvornikov V.M., Sdobnov V.E. Analyzing the Solar Proton Event of 22 October 1989, Using the Method of Spectrographic Global Survey. Solar Phys. 1998, vol. 178, pp. 405-422. DOI:https://doi.org/10.1023/A:1005069806374.
9. Dvornikov V.M., Sdobnov V.E. Variations in the rigidity spectrum and anisotropy of cosmic rays at the period of Forbush-effect on 12-15 July. Geomagnetism and Aeronomy. 2002, vol. 3, no. 3, pp. 217-226.
10. Kocharov L., Pohjolainen S., Mishev A., Reiner M.J., Lee J., Laitinen T., et. al. Investigating the origins of two extreme solar particle events: proton source profile and associated electromagnetic emissions. Astrophys. J. 2017, vol. 839, no. 2, p. 79. DOI:https://doi.org/10.3847/1538-4357/aa6a13.
11. Kravtsova M.V., Sdobnov V.E. Cosmic ray during the geomagnetic disturbance in January 2015. Cosmic Res. 2019, vol. 57, no. 1, pp. 14-17. DOI:https://doi.org/10.1134/S0010952519010052.
12. Kühl P., Dresing N., Heber B., Klassen A. Solar energetic particle events with protons above 500 MeV between 1995 and 2015 measured with SOHO/EPHIN. Solar Phys. 2017, vol. 292, no. 10. DOI:https://doi.org/10.1007/s11207-016-1033-8.
13. Logachev Y.I., Daibog E.I., Lazutin L.L., Miroshnichenko L.I., Surova G.M., Yakovchouk O.S., et.al. A comparison of proton activity in cycles 20-23. Geomagnetism and Aeronomy. 2015, vol. 55, no. 3, pp. 277-286. DOI:https://doi.org/10.1134/S0016793215030135.
14. Miroshnichenko L.I., Perez-Peraza J.A. Astrophysical aspects in the studies of solar cosmic rays. International Journal of Modern Physics A. 2008, vol. 23, no. 1, pp. 1-141.
15. Petukhov I.S., Petukhov S.I., Starodubtsev S.A., Timofeev V.E. Diffusive propagation of fast particles in the presence of a moving shock wave. Astron. Lett. 2003, vol. 29, no. 10, pp. 658-666. DOI:https://doi.org/10.1134/1.1615334.
16. Reames D.V. Particle acceleration at the Sun and in the heliosphere. Space Sci. Rev. 1999, vol. 90, pp. 413-491. DOI:https://doi.org/10.1023/A:1005105831781.
17. Richardson I.G., Cane H.V., Dvornikov V. M., Sdobnov V.E. Bidirectional particle flows at cosmic ray and lower 1 (MeV) energies and their association with interplanetary coronal mass ejections/ejecta. J. Geophys. Res. 2000, vol. 105, no. A6, pp. 12579-12591J. DOI:https://doi.org/10.1029/1999ja000331.
18. Shea M., Smart D. A summary of major solar proton events. Solar Phys. 1990, vol. 127, pp. 297-302. DOI:https://doi.org/10.1007/BF00152170.
19. Smart D., Shea M. A comparison of the magnitude of the 29 September 1989 high energy event with solar cycle 17, 18 and 19. Proc. 22nd Int. Cosmic Ray Conf. Dublin, Ireland, 1991, vol. 3, pp. 101-104.
20. Stoker P.H. Proton ground-level enhancements of the 23rd solar cycle. South African Journal of Science. 2002, vol. 98, no. 5, pp. 289-292.
21. Thakur N., Gopalswamy N., Mäkelä P., Akiyama S., Yashiro S., Xie H. Two Exceptions in the large SEP events of solar cycles 23 and 24. Solar Phys. 2016, vol. 291, pp. 513-530. DOI:https://doi.org/10.1007/s11207-015-0830-9.
22. Usoskin I., Ibragimov A., Shea M., Smart D. Database of ground level enhancements (GLE) of high energy solar proton events. Proc. 34th Int. Cosmic Ray Conf. Den Haag, the Netherlands, 2015, p. ID 054.
23. URL: http://gle.oulu.fi;nmdb.eu/nest (accessed February 8, 2022).
24. URL: http://gle.oulu.fi (accessed February 8, 2022).
25. URL: http://spaceweather.izmiran.ru/rus/fds1998.html (accessed February 8, 2022).
26. URL: https://www.solarmonitor.org (accessed February 8, 2022).
27. URL: http://omniweb.gsfc.nasa.gov (accessed February 8, 2022).
28. URL: http://cdaw.gsfc.nasa.gov/CME_list/UNIVERSAL/1998_05/univ1998_05.html (accessed February 8, 2022).
29. URL: https://www.spaceweatherlive.com/ru/arhiv/1998/05/02/kp.html (accessed February 8, 2022).
30. URL: ftp://cr0.irmiran.rssi.ru (accessed February 8, 2022).
31. URL: http://satdat.ngdc.noaa.gov./sem/goes (accessed February 8, 2022).
32. URL: http://ckp-rf.ru/ckp/3056 (accessed February 8, 2022).
33. URL: http://cr.izmiran.ru/dbs_unu.html (accessed February 8, 2022).
