Solar Physics

, 294:90 | Cite as

Solar Cycle Variation of the Heliospheric Plasma Sheet Thickness

  • Chin-Chun WuEmail author
  • Kan Liou
  • Ronald P. Lepping


Past independent studies of the heliospheric plasma sheet (HPS) have shown that the thickness is highly variable, ranging from \(\approx 3.8 \times 10^{5}\) to \(8.9 \times 10^{6}\) km. Here we conduct a survey of the previous results and find a solar cycle dependence – where the HPS tends to be wider during solar-minimum years and narrower during solar-maximum years. The HPS is thicker near solar minimum than near solar maximum by a factor of 1.6 (in Solar Cycle 23) and 8 (in Solar Cycle 24). We also found that the average HPS thickness in 2007 (near the minimum of Solar Cycle 23/24) was almost ten times larger than that in 1995 (near minimum of Solar Cycle 22/23), and it was associated with a weak polar magnetic field in 2007. Based on the solar-surface-field measurements, we found that the average solar magnetic-field strength [\(| \boldsymbol{B}|\)] at 2.5 solar radii [R] was \(\approx 40\)% larger in 1995 than in 2007 (0.22 gauss versus 0.16 gauss). We also found a larger (\(\approx 27 \)%) magnetic pressure-gradient force in 1995 than in 2007. Because this magnetic gradient force points toward the Equator in the corona (which is probably also true farther out), a wider HPS is expected to occur in 2007 than in 1995, at least close to the Sun. This result supports the so-called heliospheric plasma-sheet inflation hypothesis, i.e. the HPS is wider if the Sun’s polar field is weaker and narrower if the Sun’s polar field is stronger.


Solar cycle variation Heliospheric plasma sheet Heliospheric current sheet Heliospheric plasma-sheet inflation hypothesis Interplanetary magnetic field 



We thank the World Data Center SILSO (Sunspot Index and Long-term Solar Observations), Royal Observatory of Belgium, Brussels for proving sunspot data, and Y.-M. Wang of the Naval Research Laboratory for providing the derived solar magnetic-field data at 2.5 solar radii. The work of C.-C. Wu was supported partially by the Chief of Naval Research, and the NASA 80HQTR18T0023, HSWO2R17-0005, and 80HQTR19T0062 grants. The work of K. Liou was supported by the NSF grant 1743118 to the Johns Hopkins University Applied Physics Laboratory.

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.


  1. Baumjohann, W., Paschmann, G., Nagai, T.: 1992, Thinning and expansion of the plasma sheet. J. Geophys. Res. 97, 17173. DOI. ADSCrossRefGoogle Scholar
  2. Bavassano, B., Woo, R., Bruno, R.: 1997, Heliospheric plasma sheet and coronal streamers. Geophys. Res. Lett. 24(13), 1655. DOI. ADSCrossRefGoogle Scholar
  3. Bevington, P.R., Robinson, D.K.: 2003, Data Reduction and Error Analysis for the Physical Sciences, 3rd edn. McGraw–Hill, New York. Google Scholar
  4. Borrini, G., Gosling, J.T., Bame, S.J., Feldman, W.C., Wilcox, J.M.: 1981, Solar wind helium and hydrogen structure near the heliospheric current sheet: A signal of coronal streamers at 1 AU. J. Geophys. Res. 86(A6), 4565. DOI. ADSCrossRefGoogle Scholar
  5. Crooker, N.U., Huang, C.-L., Lamassa, S.M., Larson, D.E., Kahler, S.W., Spence, H.E.: 2004, Heliospheric plasma sheets. J. Geophys. Res. 109, A03107. DOI. ADSCrossRefGoogle Scholar
  6. Fitzenreiter, R.J., Burlaga, L.F.: 1978, Structure of current sheets in magnetic holes at 1 AU. J. Geophys. Res. 83, 5579. DOI. ADSCrossRefGoogle Scholar
  7. Foullon, C., Lavraud, B., Wardle, N.C., Owen, C.J., Kucharek, H., Fazakerley, A.N., et al.: 2009, The Apparent layered structure of the heliospheric current sheet: Multi-spacecraft observations. Solar Phys. 259, 389. DOI. ADSCrossRefGoogle Scholar
  8. Gosling, J.T., Asbridge, J.R., Bame, S.J., Feldman, W.C., Borrini, G., Hansen, R.T.: 1981, Coronal streamers in the solar wind at 1 AU. J. Geophys. Res. 86, 5438. DOI. ADSCrossRefGoogle Scholar
  9. Intriligator, D.S., Webber, W.R.: 2014, Analyses of Voyager 2 plasma observations in the heliosheath: Near the heliospheric current sheet and streamer belt. In: Hu, Q., Zank, G.P. (eds.) Outstanding Problems in Heliophysics: From Coronal Heating to the Edge of the Heliosphere, CS-484, 84. Astron. Soc. Pacific, San Francisco. ADS. Google Scholar
  10. Lepping, R.P., Szabo, A., Peredo, M., Hoeksema, J.T.: 1996, Large-scale properties and solar connection of the heliospheric current and plasma sheets: Wind observations. Geophys. Res. Lett. 23, 1199. DOI. ADSCrossRefGoogle Scholar
  11. Liou, K., Wu, C.-C.: 2016, A possible cause of the diminished solar wind during the solar cycle 23 – 24 minimum. Solar Phys. 291, 3777. DOI. ADSCrossRefGoogle Scholar
  12. Simunac, K.D.C., Galvin, A.B., Farrugia, C.J., Kistler, L.M., Kucharek, H., Lavraud, B., et al.: 2012, The heliospheric plasma sheet observed in situ by three spacecraft over four solar rotations. Solar. Phys. 281, 42. DOI. CrossRefGoogle Scholar
  13. Smith, E.: 2001, The heliospheric current sheet. J. Geophys. Res. 106, 15819. DOI. ADSCrossRefGoogle Scholar
  14. Smith, E., Zhou, X.: 2007, Slow mode waves in the heliospheric plasma sheet. In: Shaikh, D., Zank, G.P. (eds.) Turbulence and Nonlinear Processes in Astrophysical Plasmas, AIP CS-932, 144. DOI. CrossRefGoogle Scholar
  15. Suess, S.T., Ko, Y.-K., Steiger, R., Moore, R.L.: 2009, Quiescent current sheets in the solar wind and origins of slow wind. J. Geophys. Res. 114, A04103. DOI:10.1029/2008JA013704. ADSCrossRefGoogle Scholar
  16. Winterhalter, D., Smith, E.J., Burton, M.E., Murphy, N., McComas, D.J.: 1994, The heliospheric plasma sheet. J. Geophys. Res. 99(A4), 6667. DOI. ADSCrossRefGoogle Scholar
  17. Wu, C.-C., Liou, K., Plunkett, S., Craig, D.F., Wu, S.T.: 2013, Investigation of solar/heliospheric anomalies associated with solar minimum during 2007 – 2008. Terr. Atmos. Oceanic Sci. 24, 243.DOI. DOI. CrossRefGoogle Scholar
  18. Wu, C.-C., Liou, K., Wu, S.T., Dryer, M.: 2016, Heliospheric plasma sheet inflation as a cause of solar wind anomaly during the solar cycle 23 – 24 minimum. In: Wang, L., Bruno, R., Möbius, E., Vourlidas, A., Zank, G.P. (eds.) Proc. Solar Wind 14, AIP CP-1720, 040021. DOI. CrossRefGoogle Scholar
  19. Wu, C.-C., Liou, K., Lepping, R.P., Vourlidas, A., Plunkett, S., Socker, D., Wu, S.T.: 2017, Observation of an extremely large-density heliospheric plasma sheet compressed by an interplanetary shock at 1 AU. Solar Phys. 292, 109. DOI. ADSCrossRefGoogle Scholar
  20. Zhou, X.-Y., Smith, E.J., Winterhalter, D., McComas, D.J., Skoug, R.M., Goldstein, B.E., Smith, C.W.: 2005, Morphology and evolution of the heliospheric current and plasma sheets from 1 to 5 AU. In: Fleck, B., Zurbuchen, T.H., Lacoste, H. (eds.) Proc. Solar Wind 11 / SOHO 16, Connecting Sun and Heliosphere SP-592, ESA, Noordwijk, 659. ISBN 92-9092-903-0. Google Scholar

Copyright information

© This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2019

Authors and Affiliations

  1. 1.Naval Research LaboratoryWashingtonUSA
  2. 2.Applied Physics LaboratoryJohns Hopkins UniversityLaurelUSA
  3. 3.UMBC/NASA/GSFCGreenbeltUSA

Personalised recommendations