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Magnetic flux transport of decaying active regions and enhanced magnetic network

Wang, Haimin and Zirin, Harold and Ai, Guoxiang (1991) Magnetic flux transport of decaying active regions and enhanced magnetic network. Solar Physics, 131 (1). pp. 53-68. ISSN 0038-0938. doi:10.1007/bf00151744.

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Several series of coordinated observations on decaying active regions and enhanced magnetic network regions have been carried out jointly at Big Bear Solar Observatory (BBSO) and Huairou Solar Observing Station of the Bejing Astronomical Observatory in China. The evolution of magnetic fields in several regions was followed closely for 3 to 7 days. The transport of magnetic flux from the remnants of decayed active regions was studied. Three related topics are included in this paper. (1) We studied the evolution and lifetime of the magnetic network which defines the boundaries of supergranules. The results are consistent with our earlier studies: network cells have an average lifetime of about 70 hours; 68% of new cells appeared by growing from a single network magnetic element; 50% of decaying cells disappeared by contracting to a network element. (2) We studied the magnetic flux transport in an enhanced network region in detail, and found the diffusion rate to be negative, i.e., there was more flux moving towards the decayed active region than away from it. We found several other cases where the magnetic diffusion rate does not agree with Leighton's model. The slow diffusion rate is likely due to the fact that the average velocity of larger magnetic elements, which carry most of the magnetic flux, is less than 0.1 km s⁻¹; their average lifetime is longer than 100 hours. (3) We briefly described some properties of Moving Magnetic Features (MMFs) around a sunspot (detailed discussion on MMFs will be presented in a separate paper). In this particular case, the MMFs did not carry net flux away from the central spot. Instead, the polarities of MMFs were essentially mixed so that outflowing positive and negative fluxes were roughly balanced. During the 3-day period, there was almost no net flux accumulation to form a moat. The cancellation of MMFs of opposite polarities at the boundary of the super-penumbra caused quite a few surges and Hα brightenings.

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Wang, Haimin0000-0002-5233-565X
Additional Information:© 1991 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Received 8 June, 1990; in revised form 6 August, 1990. We are grateful to the observing staff at BBSO and Huairou Solar Observing Station for their support in the observations. S. F. Martin planned and directed the carrying out of the observing runs. S. H. B. Livi participated in the acquisition of the data in July 1988. The referee made valuable comments and corrections which were very helpful in improving the paper. The work at BBSO is supported by NSF under grant ATM-8513577, NASA under grant NGL 05-002-034, and Air Force Office of Scientific Research under grant AFOSR-82-0018 and at Huairou by the Academia Sinica and the National Science Foundation of China.
Funding AgencyGrant Number
NASANGL 05-002-034
Air Force Office of Scientific Research (AFOSR)AFOSR-82-0018
Academia SinicaUNSPECIFIED
National Science Foundation of ChinaUNSPECIFIED
Subject Keywords:Network Region; Magnetic Flux; Diffusion Rate; Astronomical Observatory; Average Lifetime
Issue or Number:1
Record Number:CaltechAUTHORS:20200520-140309096
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Official Citation:Wang, H., Zirin, H. & Ai, G. Magnetic flux transport of decaying active regions and enhanced magnetic network. Sol Phys 131, 53–68 (1991).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103363
Deposited By: Tony Diaz
Deposited On:20 May 2020 21:10
Last Modified:16 Nov 2021 18:20

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