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A doubling of the Sun's coronal magnetic field during the past 100 years


The solar wind is an extended ionized gas of very high electrical conductivity, and therefore drags some magnetic flux out of the Sun to fill the heliosphere with a weak interplanetary magnetic field1,2. Magnetic reconnection—the merging of oppositely directed magnetic fields—between the interplanetary field and the Earth's magnetic field allows energy from the solar wind to enter the near-Earth environment. The Sun's properties, such as its luminosity, are related to its magnetic field, although the connections are still not well understood3,4. Moreover, changes in the heliospheric magnetic field have been linked with changes in total cloud cover over the Earth, which may influence global climate5. Here we show that measurements of the near-Earth interplanetary magnetic field reveal that the total magnetic flux leaving the Sun has risen by a factor of 1.4 since 1964: surrogate measurements of the interplanetary magnetic field indicate that the increase since 1901 has been by a factor of 2.3. This increase may be related to chaotic changes in the dynamo that generates the solar magnetic field. We do not yet know quantitatively how such changes will influence the global environment.

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Figure 1: Annual means of a, the geomagnetic activity index, 〈aa 〉, and b, Sargent's recurrence index, 〈I 〉. I is defined for the j th 27-day Carrington rotation period as where c is the correlation coefficient between two consecutive 27-day intervals of 12-hourly aa values13,23.
Figure 2: Time series of observed annual means and corresponding best-fit predicted values for 1964–96.
Figure 3: The total solar magnetic flux emanating through the coronal source sphere12, F s.
Figure 4: Schematic illustration of how the IMF B sw emerges from holes in the solar atmosphere (coronal holes) and is dragged to Earth by the solar wind.


  1. 1

    Gazis, P. R. Solar cycle variation of the heliosphere. Rev. Geophys. 34, 379–402 (1996).

    ADS  Article  Google Scholar 

  2. 2

    Balogh, al. The heliospheric field over the south polar region of the sun. Science 268, 1007–1010 (1995).

    ADS  CAS  Article  Google Scholar 

  3. 3

    Willson, R. C. Total solar irradiance trend during cycles 21 and 22. Science 277, 1963–1965 (1997).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Lean, J., Beer, J. & Bradley, R. Reconstruction of solar irradiance since 1610: implications for climate change. Geophys. Res. Lett. 22, 3195–3198 (1995).

    ADS  Article  Google Scholar 

  5. 5

    Svensmark, H. & Friis-Christensen, E. Variation of cosmic ray flux and global cloud coverage—a missing link in solar-climate relationships. J. Atmos. Sol. Terr. Phys. 59, 1225–1232 (1997).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Mayaud, P. N. The aa indices: a 100-year series characterising the magnetic activity. J. Geophys. Res. 72, 6870–6874 (1972).

    ADS  Article  Google Scholar 

  7. 7

    Stamper, R., Lockwood, M., Wild, M. N. & Clark, T. D. G. Solar causes of the long-term increase in geomagnetic activity. J. Geophys. Res.(in press).

  8. 8

    Russell, C. T. On the possibility of deducing interplanetary and solar parameters from geomagnetic records. Sol. Phys. 42, 259–269 (1975).

    ADS  Article  Google Scholar 

  9. 9

    Gringauz, K. I. in Solar Wind 4(ed. Rosenbauer, H.) (Rep. MPAE-W-100-81-31, MPI für Aeronomie, Lindau, Germany, (1981).

    Google Scholar 

  10. 10

    Feynman, J. & Crooker, N. U. The solar wind at the turn of the century. Nature 275, 626–627 (1978).

    ADS  Article  Google Scholar 

  11. 11

    Baker, D. in Solar Wind-Magnetosphere Coupling(eds Kamide, Y. & Slavin, J. A.) 17–38 (Terra Scientific, Tokyo, (1986).

    Book  Google Scholar 

  12. 12

    Wang, Y.-M. & Sheeley, N. R. J Solar implications of Ulysses interplanetary field measurements. Astrophys. J. 447, L143–L146 (1995).

    ADS  Google Scholar 

  13. 13

    Cliver, E. W., Boriakoff, V. & Bounar, K. H. The 22-year cycle of geomagnetic activity. J. Geophys. Res. 101, 27091–27109 (1996).

    ADS  Article  Google Scholar 

  14. 14

    Silverman, S. W. Secular variation of the aurora for the past 500 years. Rev. Geophys. 30, 333–351 (1992).

    ADS  Article  Google Scholar 

  15. 15

    Sonnet, C. P. Long-period solar terrestrial variability. Rev. Geophys. (Suppl.: US Nat. Rep. to IUGG 1987–1990 909–914 (1991).

  16. 16

    Beer, J., Tobias, S. & Weiss, N. An active sun throughout the Maunder minimum. Sol. Phys. 181, 237–249 (1998).

    ADS  CAS  Article  Google Scholar 

  17. 17

    Feynman, J. & Gabriel, S. B. Period and phase of the 88-year solar cycle and the Maunder minimum: evidence for the chaotic sun. Sol. Phys. 127, 393–403 (1990).

    ADS  Article  Google Scholar 

  18. 18

    Cliver, E. W., Boriakoff, V. & Feynman, J. Solar variability and climate change: geomagnetic aa index and global surface temperature. Geophys. Res. Lett. 25, 1035–1038 (1998).

    ADS  Article  Google Scholar 

  19. 19

    Vasyliunas, V. M., Kan, J. R., Siscoe, G. L. & Akasofu, S.-I. Scaling relations governing magnetospheric energy transfer. Planet Space Sci. 30, 359–365 (1982).

    ADS  Article  Google Scholar 

  20. 20

    Scurry, L. & Russell, C. T. Proxy studies of energy transfer to the magnetosphere. J. Geophys. Res. 96, 9541–9548 (1991).

    ADS  Article  Google Scholar 

  21. 21

    Merrill, R. T., McElhinny, M. W. & McFadden, P. L. The Magnetic Field of the Earth 34 (Academic, San Diego, (1996).

    Google Scholar 

  22. 22

    Wang, Y.-M., Hawley, S. H. & Sheeley, N. R. J The magnetic nature of coronal holes. Science 271, 464–469 (1996).

    ADS  CAS  Article  Google Scholar 

  23. 23

    Sargent, H. H. in Solar Wind-Magnetosphere Coupling(eds Kamide, Y. & Slavin, J. A.) 143–148 (Terra Scientific, Tokyo, (1986).

    Book  Google Scholar 

  24. 24

    Hapgood, M. A. Adouble solar-cycle variation in the 27-day recurrence of geomagnetic activity. Ann Geophys. 11, 248–253 (1993).

    ADS  Google Scholar 

  25. 25

    Webb, D. F. & Howard, R. A. The solar cycle variation of coronal mass ejections and solar wind mass flux. J. Geophys. Res. 99, 4201–4220 (1994).

    ADS  Article  Google Scholar 

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The data used are stored and made available via World Data Centre C1 for STP at RAL, which is funded by the UK Particle Physics and Astronomy Research Council and, until 1 April 1999, by the National Radio Propagation Programme of the Radiocommunications Agency. We also thank the many scientists who have contributed data to the WDC.

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Correspondence to M. Lockwood.

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Lockwood, M., Stamper, R. & Wild, M. A doubling of the Sun's coronal magnetic field during the past 100 years. Nature 399, 437–439 (1999).

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