REPRODUCTION OF THE OBSERVED TWO-COMPONENT MAGNETIC HELICITY IN SOLAR WIND TURBULENCE BY A SUPERPOSITION OF PARALLEL AND OBLIQUE ALFVEN WAVES

	REPRODUCTION OF THE OBSERVED TWO-COMPONENT MAGNETIC HELICITY IN SOLAR WIND TURBULENCE BY A SUPERPOSITION OF PARALLEL AND OBLIQUE ALFVEN WAVES
	He, Jiansen; Tu, Chuanyi; Marsch, Eckart; Yao, Shuo
刊名	ASTROPHYSICAL JOURNAL
	2012
卷号	749 期号:1 页码:86
关键词	solar wind turbulence waves
ISSN号	0004-637X
通讯作者	He, JS (reprint author), Peking Univ, Dept Geophys, Beijing 100871, Peoples R China.
中文摘要	The angular distribution of the normalized reduced magnetic helicity density (sigma(r)(m)) in solar wind turbulence reveals two components of distinct polarity in different angle ranges. This kind of two-component sigma(r)(m) m may indicate the possible wave modes and power spectral densities (PSDs) of the turbulent fluctuations. Here we model the measured angular distribution of sigma(r)(m) m by assuming a PSD distribution for Alfven fluctuations in wavevector space, and then fit the model results to the observations by adjusting the pattern of the PSD distribution. It is found that the two-component form of the PSD, which has a major and minor component close to k(perpendicular to) and k(parallel to), respectively, seems to be responsible for the observed two-component sigma(r)(m). On the other hand, both an isotropic PSD and a PSD with only a single component bending toward k(perpendicular to) fail to reproduce the observations. Moreover, it is shown that the effect of gradual balance between outward and inward wave-energy fluxes with decreasing spatial scale needs to be considered in order to reproduce the observed diminishing of vertical bar sigma(r)(m)vertical bar at shorter scales. Therefore, we suggest that the observed two-component sigma(r)(m) in the solar wind turbulence may be due to a superposition of Alfven waves with quasi-perpendicular (major part) and quasi-parallel (minor part) propagation. The waves seem to become gradually balanced toward shorter scales.
英文摘要	The angular distribution of the normalized reduced magnetic helicity density (sigma(r)(m)) in solar wind turbulence reveals two components of distinct polarity in different angle ranges. This kind of two-component sigma(r)(m) m may indicate the possible wave modes and power spectral densities (PSDs) of the turbulent fluctuations. Here we model the measured angular distribution of sigma(r)(m) m by assuming a PSD distribution for Alfven fluctuations in wavevector space, and then fit the model results to the observations by adjusting the pattern of the PSD distribution. It is found that the two-component form of the PSD, which has a major and minor component close to k(perpendicular to) and k(parallel to), respectively, seems to be responsible for the observed two-component sigma(r)(m). On the other hand, both an isotropic PSD and a PSD with only a single component bending toward k(perpendicular to) fail to reproduce the observations. Moreover, it is shown that the effect of gradual balance between outward and inward wave-energy fluxes with decreasing spatial scale needs to be considered in order to reproduce the observed diminishing of vertical bar sigma(r)(m)vertical bar at shorter scales. Therefore, we suggest that the observed two-component sigma(r)(m) in the solar wind turbulence may be due to a superposition of Alfven waves with quasi-perpendicular (major part) and quasi-parallel (minor part) propagation. The waves seem to become gradually balanced toward shorter scales.
学科主题	空间物理
收录类别	SCI
资助信息	National Natural Science Foundation of China [41174148, 40890162, 40931055]; Specialized Research Fund for State Key Laboratories of China; Research Fund for the Doctoral Program of Higher Education of China [20110001120116]; Fundamental Research Funds for the Central Universities [2011YYL127]
语种	英语
公开日期	2014-12-15
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/3264]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	He, Jiansen,Tu, Chuanyi,Marsch, Eckart,et al. REPRODUCTION OF THE OBSERVED TWO-COMPONENT MAGNETIC HELICITY IN SOLAR WIND TURBULENCE BY A SUPERPOSITION OF PARALLEL AND OBLIQUE ALFVEN WAVES[J]. ASTROPHYSICAL JOURNAL,2012,749(1):86.
APA	He, Jiansen,Tu, Chuanyi,Marsch, Eckart,&Yao, Shuo.(2012).REPRODUCTION OF THE OBSERVED TWO-COMPONENT MAGNETIC HELICITY IN SOLAR WIND TURBULENCE BY A SUPERPOSITION OF PARALLEL AND OBLIQUE ALFVEN WAVES.ASTROPHYSICAL JOURNAL,749(1),86.
MLA	He, Jiansen,et al."REPRODUCTION OF THE OBSERVED TWO-COMPONENT MAGNETIC HELICITY IN SOLAR WIND TURBULENCE BY A SUPERPOSITION OF PARALLEL AND OBLIQUE ALFVEN WAVES".ASTROPHYSICAL JOURNAL 749.1(2012):86.