期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
卷 118, 期 3, 页码 1089-1100出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/jgra.50145
关键词
-
资金
- Chinese Academy of Sciences (CAS) [2012T1G0018]
- STFC [ST/I003649/1] Funding Source: UKRI
- Grants-in-Aid for Scientific Research [24740337] Funding Source: KAKEN
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [0847120] Funding Source: National Science Foundation
- Science and Technology Facilities Council [ST/I003649/1] Funding Source: researchfish
Previous works have emphasized the significant influence of the solar wind Alfven Mach number (M-A) on magnetospheric dynamics. Here we report statistical, observational results that pertain to changes in the magnetosheath flow distribution and magnetopause shape as a function of solar wind M-A and interplanetary magnetic field (IMF) clock angle orientation. We use all Cluster 1 data in the magnetosheath during the period 2001-2010, using an appropriate spatial superposition procedure, to produce magnetosheath flow distributions as a function of location in the magnetosheath relative to the IMF and other parameters. The results demonstrate that enhanced flows in the magnetosheath are expected at locations quasi-perpendicular to the IMF direction in the plane perpendicular to the Sun-Earth line; in other words, for the special case of a northward IMF, enhanced flows are observed on the dawn and dusk flanks of the magnetosphere, while much lower flows are observed above the poles. The largest flows are adjacent to the magnetopause. Using appropriate magnetopause crossing lists (for both high and low M-A), we also investigate the changes in magnetopause shape as a function of solar wind M-A and IMF orientation. Comparing observed magnetopause crossings with predicted positions from an axisymmetric semi-empirical model, we statistically show that the magnetopause is generally circular during high M-A, while is it elongated (albeit with moderate statistical significance) along the direction of the IMF during low M-A. These findings are consistent with enhanced magnetic forces that prevail in the magnetosheath during low M-A. The component of the magnetic forces parallel to the magnetopause produces the enhanced flows along and adjacent to the magnetopause, while the component normal to the magnetopause exerts an asymmetric pressure on the magnetopause that deforms it into an elongated shape.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据