Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field

Owens, M. J. ORCID: https://orcid.org/0000-0003-2061-2453, Crooker, N. U., Schwadron, N. A., Horbury, T. S., Yashiro, S., Xie, H., St. Cyr, O. C. and Gopalswamy, N. (2008) Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field. Geophysical Research Letters, 35 (20). L20108. ISSN 0094-8276 doi: 10.1029/2008GL035813

Abstract/Summary

The near-Earth heliospheric magnetic field intensity, |B|, exhibits a strong solar cycle variation, but returns to the same ``floor'' value each solar minimum. The current minimum, however, has seen |B| drop below previous minima, bringing in to question the existence of a floor, or at the very least requiring a re-assessment of its value. In this study we assume heliospheric flux consists of a constant open flux component and a time-varying contribution from CMEs. In this scenario, the true floor is |B| with zero CME contribution. Using observed CME rates over the solar cycle, we estimate the ``no-CME'' |B| floor at ~4.0 +/- 0.3 nT, lower than previous floor estimates and below |B| observed this solar minimum. We speculate that the drop in |B| observed this minimum may be due to a persistently lower CME rate than the previous minimum, though there are large uncertainties in the supporting observational data.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/5821
Item Type	Article
Refereed	Yes
Divisions	No Reading authors. Back catalogue items
Uncontrolled Keywords	Solar Physics, Astrophysics, and Astronomy: Solar activity cycle (2162), Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections (2101), Solar Physics, Astrophysics, and Astronomy: Solar and stellar variability (1650), Interplanetary Physics: Ejecta, driver gases, and magnetic clouds, Interplanetary Physics: Interplanetary magnetic fields
Publisher	American Geophysical Union
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