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Weak solar fields and their connection to the solar cycle

Zirin, Harold (1987) Weak solar fields and their connection to the solar cycle. Solar Physics, 110 (1). pp. 101-107. ISSN 0038-0938. https://resolver.caltech.edu/CaltechAUTHORS:20200602-084457203

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Abstract

We discuss the weak solar magnetic fields as studied with the BBSO videomagnetograph (VMG). By weak fields we mean those outside active and unipolar regions. These are found everywhere on the Sun, even where there never have been sunspots. These fields consist of the network and intranetwork (IN) elements. The former move slowly and live a day or more; the latter move rapidly (typically 300 m s⁻¹) and live only hours. To all levels of sensitivity the flux is concentrated in discrete elements, and the background field has not been detected. The smallest detectable elements at present are 10¹⁶ Mx. The IN elements emerge in bipolar form but appear to flow in a random pattern rather than to the network edges; however, any expanding network element is constrained by geometry to move toward the edges. Because of the great number and short lifetime of the IN elements the total flux emerging in that form exceeds that emerging in the ER by two orders of magnitude and the flux in sunspots, by a factor 104. However, the flux separation is small and there is no contribution to the overall field. In contrast with our earlier results, merging of IN fields is more important than the ephemeral regions as a source of new network elements. The conjecture that all solar magnetic fields are intrinsically strong is discussed and evidence pro and con presented. For the IN fields the evidence suggests they cannot exceed 100 G. For the network fields there is evidence on either side. Reconnection and merging of magnetic fields takes place continually in the conditions studied. Because there is a steady state distribution, the amout of new elements created by merging or emergence must balance that destroyed by reconnection or fission and diffusion of the stronger elements.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/bf00148205DOIArticle
https://ui.adsabs.harvard.edu/abs/1987SoPh..110..101Z/abstractADSArticle
Additional Information:© 1987 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Solar Cycle Workshop Paper. I acknowledge the work of the Big Bear staff in maintaining the high quality of the VMG observations. This work was supported by NASA under grant NGL 05 002 034 and by the NSF Solar Terrestrial program under ATM-8513577.
Funders:
Funding AgencyGrant Number
NASANGL 05 002 034
NSFATM-8513577
Subject Keywords:Solar Cycle; Discrete Element; Weak Field; Total Flux; Random Pattern
Issue or Number:1
Record Number:CaltechAUTHORS:20200602-084457203
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200602-084457203
Official Citation:Zirin, H. Weak solar fields and their connection to the solar cycle. Sol Phys 110, 101–107 (1987). https://doi.org/10.1007/BF00148205
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103634
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Jun 2020 15:54
Last Modified:02 Jun 2020 15:54

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