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Magnetic clouds, cosmic ray decreases, and geomagnetic storms

Abstract

The relationship between magnetic clouds, cosmic ray decreases and geomagnetic storms has been investigated by using some cosmic ray hourly intensities recorded with ground-based monitors at Alert, Deep River and Mount Washington, as well as the geomagnetic activity Dst index, and the interplanetary magnetic field (IMF) and the solar wind plasma (SWP) bulk-speed, density and temperature in the near-Earth space, on 28–30 September 1978, 24–26 April 1979, 13–15 January 1967, 3–5 January 1978, and 27–29 November 1989. Due to the interplanetary coronal mass ejection (ICME) impacting on slow solar wind, there is a sheath upstream of the ICME led by a fast forward shock. And the large IMF variations in this sheath, which sustain the depressions in the cosmic ray intensity during Forbush decreases (FDs), were found not to influence the main phase storm, but rather the southward IMF in the said sheath and magnetic cloud was the major source in triggering geomagnetic storms, by allowing a strong coupling between the solar wind and the magnetosphere. It was also observed that the initial set of the main phase storm always began in the sheath where, and when, the sustained southward-oriented IMF first occurred, but ceased when the IMF was rotated to a strong northward-orientation, only to resume at subsequent sustained southward-oriented IMF within the sheath and the leading (i.e., front) region of the magnetic cloud. The front boundary of the magnetic cloud was found to be well defined by the relatively high (10 nT) rms of the IMF components, which prominently separates both the Lull region of the sheath and the onset of the second decrease of the two-step FD, from the magnetic cloud. There were some instances where a two-step main phase storm, caused by the combination of a sheath and cloud structure, occurred, the two steps sometimes both starting in the sheath itself. Also, in some cases, the sheath and the leading region of the magnetic cloud together produced a single-step storm. In addition, enhanced IMF south latitude and IMF intensity in the sheath and magnetic cloud during the IMF sustained southern orientation, were each observed to produce enhanced geomagnetic activity, even for intense storms. And high SWP bulk speed was found to reduce the depth of the Dst index. Therefore, it appears that when the magnetosphere is exposed to a sustained southward-oriented IMF in the magnetic cloud and the sheath preceding it, a valve (i.e., valve-like IMF direction) opens and allows direct transfer of energy between the solar wind and the magnetosphere to trigger the geomagnetic storms, such that the stronger the sustained IMF south-ward orientation, the wider the valve opens, the higher the SWP bulk speed, the narrower the opening in the valve becomes. And the more the IMF strength during the IMF southern orientation, the larger is the solar wind energy density that is available for transfer through the valve. The valve closes when the IMF is rotated to a strong northward-orientation, and the geomagnetic storms cease.

Index terms: 2104 Interplanetary Physics: Cosmic rays; 2111 Interplanetary Physics: Ejecta, driver gases, and magnetic clouds; 2139 Interplanetary Physics: Interplanetary shocks; 7513 Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections.

References

  1. Baker, D. N., S. I. Akasofu, W. Baumjohann, J. W. Bieber, D. H. Fairfield, E. W. Hones, Jr., B. Mauk, R. L. McPherron, and T. E. Moore, Substorms in the magnetosphere, in Solar Terrestrial Physics, Present and Future, NASA Ref Pubs. 1120, edited by D. M. Butler and K. Papadupoulos, p. 8, NASA, Washington, D.C., 1984.

    Google Scholar 

  2. Bavassano, B., M. Storini, N. Iucci, and M. Parisi, Some properties of socalled magnetic cloud structures in the solar wind, Adv. Space Res., 9, 63–68, 1989.

    Article  Google Scholar 

  3. Burlaga, L. F., Magnetic Clouds, in Physics of the Inner Heliosphere, Vol. 2, edited by R. Schwenn and E. Marsch, Springer-Verlag, New York, 1991.

  4. Burlaga, L. F., Sittler, F. Mariani, and R. Schwenn, Magnetic loop behind an interplanetary shock: Voyager, Helios and IMP 8 observations, J. Geophys. Res., 86, 6673–6684, 1981.

    Article  Google Scholar 

  5. Burton, R. K., R. L. McPherron, and C. T. Russel, An empirical relationship between interplanetary conditions and Dst, J. Geophys. Res., 80, 4204–4214, 1975.

    Article  Google Scholar 

  6. Cane, H. V., I. G. Richardson, T. T. von Rosenvinge, and G. Wibberenz, Cosmic ray decreases and shock structure: A multispacecraft study, J. Geophys. Res., 49, 21429–21441, 1994.

    Article  Google Scholar 

  7. Diego, P., M. Storini, M. Parisi, and E. G. Cordaro, AE index variability during corotating fast solar wind streams, J. Geophys. Res., 110, A06105, doi:10.1029/2004JA 010715, 2005.

  8. Dungey, J. W., Interplanetary magnetic field and the auroral zones, Phys. Rev. Lett., 6, 47–48, 1961.

    Article  Google Scholar 

  9. Feldstein, Y. I., Modelling of the magnetic field of magnetospheric ring current as a function of interplanetary parameters, Space Sc. Revs., 59, 83–165, 1992.

    Article  Google Scholar 

  10. Gonzalez, W. D. and B. T. Tsurutani, Criteria of interplanetary parameters causing intense magnetic storms (Dst < −100 nT), Planet. Space Sci., 35, 1101–1109, 1987.

    Article  Google Scholar 

  11. Gonzalez, W. D., B. T. Tsurutani, A. L. C. Gonzalez, E. J. Smith, F. Tang, and S. I. Akasofu, Solar wind—magnetosphere coupling during intense magnetic storms (1978–1979), J. Geophys. Res., 94, 8835–8851, 1989.

    Article  Google Scholar 

  12. Gonzalez, W. D., J. A. Joselyn, Y. Kamide, H. W. Krochl, G. Rostoker, B. T. Tsurutani, and V. M. Vasyliunas, What is a geomagnetic storm?, J. Geophys. Res., 99, 5771–5792, 1994.

    Article  Google Scholar 

  13. Gonzalez, W. D., A. L. C. Gonzalez, J. H. A. Sobral, A. D. Lago, and L. Vieira, Solar and interplanetary causes of very intense geomagnetic storms, J. Atmos. Sol. Terr. Phys., 63, 403–412, 2001.

    Article  Google Scholar 

  14. Gosling, J. T., Coronal mass ejections: The link between solar and geomagnetic activity, Phys. Fluids, B, 5(7) 2638–2645, 1993a.

    Article  Google Scholar 

  15. Gosling, J. T., The solar flare myth, J. Geophys. Res., 98, 18937–18949, 1993b.

    Article  Google Scholar 

  16. Grafe, A., The influence of the recovery phase injection on the decay of the ring current, Planet. Space Sci., 36, 765–773, 1988.

    Article  Google Scholar 

  17. Ifedili, S. O., Forbush decrease of June 8, 1969: Causes of the unusually long recovery, Earth Planets Space, 53, 993–999, 2001.

    Article  Google Scholar 

  18. Ifedili, S. O., The two-step Forbush decrease: An empirical model, J. Geophys. Res., 109, A002117, doi: 10.1029/2002JA009814, 1–12, 2004.

    Google Scholar 

  19. Iucci, N., M. Parisi, C. Signorini, M. Storini, and G. Villoresi, Short-term cosmic ray increases and magnetic cloud-like structures during Forbush decreases, Astron. Astrophys. Suppl. Ser., 81, 367–391, 1989.

    Google Scholar 

  20. King, J. H., Interplanetary Medium Data Book, Rep. NSSDC/WDC — A - R & S 77 — 04a, NASA Goddard Space Flight Cent., Greenbelt, Md, 1977.

    Google Scholar 

  21. King, J. H., Interplanetary Medium Data Book, Rep. NSSDC/WDC — A - R & S 83 — 01, NASA Goddard Space Flight Cent., Greenbelt Md, 1983.

    Google Scholar 

  22. King, J. H. and N. E. Papitashvili, Interplanetary Medium Data Book, Rep. NSSDC/WDC — A — R & S 94 — 08, NASA Goddard Space Flight Cent., Greenbelt, Md, 1994.

    Google Scholar 

  23. Klein, L. W. and L. F. Burlaga, Interplanetary magnetic clouds at 1 AU, J. Geophys. Res., 89, 613–624, 1982.

    Article  Google Scholar 

  24. Maltsev, Y. P., The points of controversy in magnetic storm study (Review), Proc. XXVI Annual Seminar “Physics of Auroral Phenomena”, Apatity, Russia, pp. 33–40, 2003.

    Google Scholar 

  25. O’Brien, T. P. and R. L. McPheron, An empirical phase space analysis of ring current dynamics: Solar wind control of injection and decay, J. Geophys. Res., 105, 7707–7719, 2000.

    Article  Google Scholar 

  26. Pudovkin, M. I., A. Grafe, S. A. Zaitseva, L. Z. Sizova, and A. V. Usmanov, Calculating the Dst-variation field on the basis of solar wind parameters, Gerlands Beitr. Geophysik., 97(6), 525–533, 1988.

    Google Scholar 

  27. Storini, M., Galactic cosmic-ray modulation and solar-terrestrial relationships, Nuovo Cimento Soc. Ital. Fis, C, 13, 103–124, 1990 (Errata corrige, Nuovo Cimento Soc. Ital. Fis. C, 14, 211, 1991.)

    Article  Google Scholar 

  28. Tsurutani, B. T. and W. D. Gonzalez, The interplanetary causes of magnetic storms, in Magnetic Storms, Geophys. Monogr. Ser. Vol. 98, edited by B. T. Tsurutani et al., pp. 77–89, AGU, Washington, D.C., 1997.

    Google Scholar 

  29. Valdivia, J. A., A. S. Sharma, and K. Papadopoulos, Prediction of magnetic storms by nonlinear models, Geophys. Res. Lett., 23, 2899–2902, 1996.

    Article  Google Scholar 

  30. Wu, C. C. and R. P. Lepping, Effects of magnetic clouds on the occurrence of geomagnetic storms: The first 4 years of Wind, J. Geophys. Res., 107(A10), 1314, doi: 10.1029/2001JA000161, 2002.

    Article  Google Scholar 

  31. Zhang, G. and L. F. Burlaga, Magnetic clouds, geomagnetic disturbances, and cosmic ray decreases, J. Geophys. Res., 93, 2511–2518, 1988.

    Article  Google Scholar 

  32. Zhang, J., M. W. Liemohn, J. U. Kozyra, B. J. Lynch, and T. H. Zurbuchen, A statistical study of the geoeffectiveness of magnetic clouds during high solar activity years, J. Geophys. Res., 109, A09101, doi: 10.1029/2004JA010410, 1-12, 2004.

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Ifedili, S.O. Magnetic clouds, cosmic ray decreases, and geomagnetic storms. Earth Planet Sp 58, 659–666 (2006). https://doi.org/10.1186/BF03351963

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  • Cosmic ray modulation
  • magnetic clouds
  • interplanetary shocks
  • coronal mass ejections
  • geomagnetic storms
  • space weather