Possible Noise Nature of Elsasser Variable z(-) in Highly Alfvenic Solar Wind Fluctuations
文献类型：期刊论文
| 作者 | Wang, X.; Tu, C. -Y.; He, J. -S.; Wang, L. -H.; Yao, S.; Zhang, L.; Tu, CY (reprint author), Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China. |
| 刊名 | JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
 |
| 出版日期 | 2018 |
| 卷号 | 123期号:1页码:57-67 |
| ISSN号 | 2169-9380 |
| 英文摘要 | It has been a long-standing debate on the nature of Elsasser variable z(-) observed in the solar wind fluctuations. It is widely believed that z(-) represents inward propagating Alfven waves and interacts nonlinearly with z(+) (outward propagating Alfven waves) to generate energy cascade. However, z(-) variations sometimes show a feature of convective structures. Here we present a new data analysis on autocorrelation functions of z(-) in order to get some definite information on its nature. We find that there is usually a large drop on the z(-) autocorrelation function when the solar wind fluctuations are highly Alfvenic. The large drop observed by Helios 2 spacecraft near 0.3AU appears at the first nonzero time lag r = 81s, where the value of the autocorrelation coefficient drops to 25%-65% of that at r = 0s. Beyond the first nonzero time lag, the autocorrelation coefficient decreases gradually to zero. The drop of z(-) correlation function also appears in the Wind observations near 1AU. These features of the z(-) correlation function may suggest that z(-) fluctuations consist of two components: high-frequency white noise and low-frequency pseudo structures, which correspond to flat and steep parts of z(-) power spectrum, respectively. This explanation is confirmed by doing a simple test on an artificial time series, which is obtained from the superposition of a random data series on its smoothed sequence. Our results suggest that in highly Alfvenic fluctuations, z(-) may not contribute importantly to the interactions with z(+) to produce energy cascade. |
| 语种 | 英语 |
| 资助机构 | National Natural Science Foundation of China [41504130, 41474147, 41674171, 41231069] ; Young Elite Scientists Sponsorship Program by China Association for Science and Technology [2016QNRC001] |
| 源URL | [http://ir.nssc.ac.cn/handle/122/6204]  |
| 专题 | 国家空间科学中心_空间科学部 |
| 通讯作者 | Tu, CY (reprint author), Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China. |
| 推荐引用方式 GB/T 7714 | Wang, X.,Tu, C. -Y.,He, J. -S.,et al. Possible Noise Nature of Elsasser Variable z(-) in Highly Alfvenic Solar Wind Fluctuations[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2018,123(1):57-67. |
| APA | Wang, X..,Tu, C. -Y..,He, J. -S..,Wang, L. -H..,Yao, S..,...&Tu, CY .(2018).Possible Noise Nature of Elsasser Variable z(-) in Highly Alfvenic Solar Wind Fluctuations.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,123(1),57-67. |
| MLA | Wang, X.,et al."Possible Noise Nature of Elsasser Variable z(-) in Highly Alfvenic Solar Wind Fluctuations".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 123.1(2018):57-67. |
入库方式： OAI收割
来源：国家空间科学中心
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。