MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION
文献类型：期刊论文
| 作者 | Zhang, Hongqi1 ; Brandenburg, Axel2,3,4; Sokoloff, D. D.5,6
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| 刊名 | ASTROPHYSICAL JOURNAL LETTERS
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| 出版日期 | 2014-04-01 |
| 卷号 | 784期号:2 |
| 关键词 | dynamo Sun: activity Sun: magnetic fields sunspots turbulence |
| 英文摘要 | We compute for the first time the magnetic helicity and energy spectra of the solar active regionNOAA 11158 during 2011 February 11-15 at 20 degrees southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of the magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The magnetic helicity normalized to its theoretical maximum value, here referred to as relative helicity, is around 4% and strongest at intermediate wavenumbers of k approximate to 0.4Mm(-1), corresponding to a scale of 2 pi/k approximate to 16 Mm. The same sign and a similar value are also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The modulus of the magnetic helicity spectrum shows a k(-11/3) power law at large wavenumbers, which implies a k(-5/3) spectrum for the modulus of the current helicity. A k(-5/3) spectrum is also obtained for the magnetic energy. The energy spectra evaluated separately from the horizontal and vertical fields agree for wavenumbers below 3 Mm(-1), corresponding to scales above 2 Mm. This gives some justification to our assumption of isotropy and places limits resulting from possible instrumental artifacts at small scales. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000333333400028 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/6475]  |
| 专题 | 国家天文台_太阳物理研究部 |
| 作者单位 | 1.Chinese Acad Sci, Natl Astron Observ, Key Lab Solar Act, Beijing 100012, Peoples R China 2.KTH Royal Inst Technol, NORDITA, SE-10691 Stockholm, Sweden 3.Stockholm Univ, SE-10691 Stockholm, Sweden 4.Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, SE-10691 Stockholm, Sweden 5.Moscow MV Lomonosov State Univ, Dept Phys, Moscow 119992, Russia 6.Russian Acad Sci, Pushkov Inst Terr Magnetism Ionosphere & Radiowav, Moscow 142190, Russia |
| 推荐引用方式 GB/T 7714 | Zhang, Hongqi,Brandenburg, Axel,Sokoloff, D. D.. MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION[J]. ASTROPHYSICAL JOURNAL LETTERS,2014,784(2). |
| APA | Zhang, Hongqi,Brandenburg, Axel,&Sokoloff, D. D..(2014).MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION.ASTROPHYSICAL JOURNAL LETTERS,784(2). |
| MLA | Zhang, Hongqi,et al."MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION".ASTROPHYSICAL JOURNAL LETTERS 784.2(2014). |
入库方式： OAI收割
来源：国家天文台
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