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Vorticity Within Bu...
Vorticity Within Bursty Bulk Flows : Convective Versus Kinetic
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- Zhang, L. Q. (author)
- Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
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- Wang, Chi. (author)
- Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
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- Dai, L. (author)
- Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
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- Baumjohann, W. (author)
- Austrian Acad Sci, Space Res Inst, Graz, Austria.
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- Lui, A. T. Y. (author)
- Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
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- Burch, James L. (author)
- Southwest Res Inst San Antonio, San Antonio, TX USA.
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- Khotyaintsev, Yuri V. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Ren, Y. (author)
- Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
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Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China Austrian Acad Sci, Space Res Inst, Graz, Austria. (creator_code:org_t)
- American Geophysical Union (AGU), 2022
- 2022
- English.
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In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 127:3
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https://uu.diva-port... (primary) (Raw object)
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Abstract
Subject headings
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- Based on four-point Magnetospheric Multiscale observation, we carefully analyze the vorticity field in the course of a reconnection jet on 27 June 2017. In this event, the convective electric field (E-c) is overwhelmed by the kinetic electric field (E-k). Accordingly, the omega-field in the course of the BBF is dominated by kinetic vorticity (omega(k)). The omega-field in the E-k-dominated bursty bulk flow (BBF) is characterized by perpendicular anisotropy. Comparison of velocity-curl vorticity (omega= backward difference xV $\mathbf{\omega }=\nabla \times \mathbf{V}$) with E/B induced vorticity confirms a greater contribution to the BBF vorticity by E (omega E=(B. backward difference )E/B2 ${\mathbf{\omega }}_{\mathbf{E}}=(\mathbf{B}\cdot \nabla )\boldsymbol{E}/{\boldsymbol{B}}<^>{2}$) than by B (omega B=(E. backward difference )B/B2 ${\mathbf{\omega }}_{\mathbf{B}}=(\mathbf{E}\cdot \nabla )\mathbf{B}/{\boldsymbol{B}}<^>{2}$). Power spectrum density reveals that in the E-k-dominated BBF, the E-c and E-k spectra have different power laws. E-c dominates the B-spectrum while E-k dominates the E-spectrum. The E-c(B) spectrum has a -5/3-like slope below 0.25 Hz but a -3-like above 0.25 Hz. The E-k(E) spectrum is -5/3-like at the low-frequency end (below 0.1 Hz) but -2-like at the high-frequency end (above 2 Hz). Within its medium frequency range, the spectrum is flat. Particularly, the E-k(E) spectrum exhibits the bump at 1-2 Hz in the frequency domain. The solitary/bipolar E-spikes, with typical temporal scale of 0.3-1 s, are likely responsible for the E-bump. Finally, we statistically analyze and compare the vorticity field in E-k-dominated and E-c -dominated BBFs. The result demonstrates that the E-k-dominated BBF tends to have stronger vorticity than the E-c -dominated BBF.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- kinetic vorticity
- convective vorticity
- BBF
- kinetic E
- convective E
- eddy turbulence
Publication and Content Type
- ref (subject category)
- art (subject category)
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