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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; He, JS (reprint author), Peking Univ, Dept Geophys, Beijing 100871, Peoples R China.
Department空间科学部
Source PublicationASTROPHYSICAL JOURNAL
2012
Volume749Issue:1Pages:86
ISSN0004-637X
Language英语
KeywordSolar Wind Turbulence Waves
AbstractThe 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.; 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.
Indexed BySCI
Funding Project中国科学院空间科学与应用研究中心
Document Type期刊论文
Identifierhttp://ir.nssc.ac.cn/handle/122/3264
Collection空间科学部
Corresponding AuthorHe, JS (reprint author), Peking Univ, Dept Geophys, Beijing 100871, Peoples R China.
Recommended Citation
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,&He, JS .(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.
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