Electric current density calculation and error analysis of solar active regions

doi:10.1016/j.newast.2008.09.002

YNAO OpenIR > 太阳物理研究组

	Electric current density calculation and error analysis of solar active regions
	Liang HF(梁红飞)1,2 ; Ma, L 1; Zhao, HJ 3; Xiang, FY 4; Liang, HF (reprint author), Yunnan Normal Univ, Div Phys, Kunming 650011, Yunnan, Peoples R China.
发表期刊	NEW ASTRONOMY
	2009-04
卷号	14 期号:3 页码:294-301
DOI	10.1016/j.newast.2008.09.002
产权排序	第2完成单位
收录类别	SCI
关键词	Sun: Sunspots Sun: Vector Magnetic Field Electric Current Density
摘要	This investigation centers upon calculating the vertical electric current densities from the two transverse components of vector magnetograms. The electric current density calculated by using the differential form of Ampere's law, j(z) = 1/mu(0) (del x B)(z), on the basis of spatially sampled transverse magnetic fields varies widely over an active region. In order to investigate how errors in the vector magnetograph measurements produce errors in the vertical electric current densities, we have numerically simulated the effects of random noise on a standard photospheric magnetic configuration produced by electric currents satisfying the force-free field conditions. We have also compared the results of the densities calculated by three different methods, and analyzed the reason inducing the differences in the results. The three methods are (1) to calculate the density using the differential form of Ampere's law j(z) = 1/mu(0) (del x B)(z); (2) to calculate the density using the integral form of Ampere's law along the square with edges at (x - Delta x, y - Delta y), (x + Delta x, y - Delta y), (x + Delta x, y + Delta y), (x - Delta x, y + Delta y) (hereafter small integral path) j(z) = (1/mu(0) closed integral(C1) B(t).dl)/dS; (3) to calculate the density by using the integral form of Ampere's law along the square with edges at (x - 2 Delta x, y - 2 Delta y), (x + 2 Delta x, y - 2 Delta y), (x + 2 Delta x, y + 2 Delta y), (x - 2 Delta x, y + 2 Delta y) (hereafter big integral path), j(z) = (1/mu(0) closed integral(C2) B(t).dl)/dS. It is found that the uncertainty of the measured electric current density increases along with the decreasing of the spatial pixel size ds. When the spatial pixel size of vector magnetograms is small enough, properly expanding the integral path can help us decrease the effect of random noise and demodulate the "true" electric current density from the measured transverse magnetograms. Close attention should be paid to the fact that some true fine-structure of the electric current density will be lost when the integral path exceeds the linear size of the smallest spatially resolved structure in the studied magnetogram. (C) 2008 Elsevier B.V. All rights reserved.
项目资助者	NSFC/Astronomy Associated Fund
语种	英语
学科领域	Astronomy & Astrophysics
文章类型	Article
ISSN	1384-1076
URL	查看原文
WOS记录号	WOS:000261990100011
WOS研究方向	Astronomy & Astrophysics
WOS类目	Astronomy & Astrophysics
关键词[WOS]	VECTOR MAGNETOGRAPH DATA ; MAGNETIC-FIELD ; HELICITY ; ALPHA(AR) ; CORONA
引用统计	被引频次：1[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ynao.ac.cn/handle/114a53/6143
专题	太阳物理研究组
通讯作者	Liang, HF (reprint author), Yunnan Normal Univ, Div Phys, Kunming 650011, Yunnan, Peoples R China.
作者单位	1.Yunnan Normal University, Physics Division, Kunming 650011, Yunnan, China 2.National Astronomical Observatories/Yunnan Observatory, CAS, Kunming 650011, China 3.National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China 4.Xiangtan University, Hunan, China
第一作者单位	中国科学院云南天文台
推荐引用方式 GB/T 7714	Liang HF,Ma, L,Zhao, HJ,et al. Electric current density calculation and error analysis of solar active regions[J]. NEW ASTRONOMY,2009,14(3):294-301.
APA	Liang HF,Ma, L,Zhao, HJ,Xiang, FY,&Liang, HF .(2009).Electric current density calculation and error analysis of solar active regions.NEW ASTRONOMY,14(3),294-301.
MLA	Liang HF,et al."Electric current density calculation and error analysis of solar active regions".NEW ASTRONOMY 14.3(2009):294-301.

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