Scale sizes of magnetosheath jets
File(s)lnj_v8.pdf (1.44 MB)
Accepted version
Author(s)
Plaschke, Ferdinand
Hietala, Heli
Vörös, Zoltan
Type
Journal Article
Abstract
Magnetosheath jets are plasma entities that feature a significantly enhanced dynamic pressure with respect to the ambient plasma. They occur more often downstream of the quasi‐parallel bow shock. Jets can propagate through the entire magnetosheath and impact on the magnetopause. We reanalyze multi‐spacecraft data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission to obtain the first unbiased distributions of scale sizes of the jets, in the directions parallel and perpendicular to their propagation direction. These distributions are log‐normal; they fit well to the observations. We argue that jet scales should be log‐normally distributed as they should result from multiplicative processes in the foreshock and in the magnetosheath. We find that typical jet scales are on the order of 0.1 Earth radii (RE), one order of magnitude smaller than previously reported. Median scale sizes of 0.12 RE and 0.15 RE in the perpendicular and parallel directions are obtained. The small scales may be related to the substructure of Short Large Amplitude Magnetic Structures (SLAMS) in the foreshock, or to the break up of larger jets within the magnetosheath. Use of the log‐normal distributions also allows for an analysis of impact rates of small‐scale jets: While previous results on large jets hitting the magnetopause several times per hour remain largely unchanged, we now find that hundreds to thousands of mostly small‐scale jets could potentially impact the dayside magnetopause every hour.
Date Issued
2020-09
Date Acceptance
2020-08-11
Citation
Journal of Geophysical Research: Space Physics, 2020, 125 (9), pp.1-12
ISSN
2169-9380
Publisher
American Geophysical Union (AGU)
Start Page
1
End Page
12
Journal / Book Title
Journal of Geophysical Research: Space Physics
Volume
125
Issue
9
Copyright Statement
©2020. American Geophysical Union. All Rights Reserved. This is the accepted version of the following article: Plaschke, F., Hietala, H., & Vörös, Z. (2020). Scale sizes of magnetosheath jets. Journal of Geophysical Research: Space Physics, 125, e2020JA027962, which has been published in final form at https://doi.org/10.1029/2020JA027962
Identifier
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JA027962
Subjects
0201 Astronomical and Space Sciences
0401 Atmospheric Sciences
Publication Status
Published
Date Publish Online
2020-09-05