Alternative interpretation of results from Kelvin‐Helmholtz vortex identification criteria

Plaschke, Ferdinand; Taylor, M. G. G. T.; Nakamura, R.

doi:10.1002/2013gl058948

Cited by 11 publications

(11 citation statements)

References 24 publications

(34 reference statements)

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“…For northward IMF and significantly sunward of the terminator the surface waves with presence of the plasma depletion layer can also show this feature (Plaschke et al, 2014). The present event occurs very close to the dawn-dusk terminator, at higher latitudes and for different IMF orientation (with |B x | > |B y | > |B z |) so the present observations cannot be directly compared with those by Plaschke et al (2014). Figure 3c presents specific entropy for the electrons (normalized to the minimum electron entropy) versus electron velocity.…”

Section: Scatter Plot Characterization Of Boundary Layer Plasma and Vmentioning

confidence: 83%

MMS Observations of the Multiscale Wave Structures and Parallel Electron Heating in the Vicinity of the Southern Exterior Cusp

Nykyri

Burkholder

et al. 2021

JGR Space Physics

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Understanding the physical mechanisms responsible for the cross-scale energy transport and plasma heating from solar wind into the Earth's magnetosphere is of fundamental importance for magnetospheric physics and for understanding these processes in other places in the universe with comparable plasma parameter ranges. This paper presents observations from the Magnetosphere Multiscale (MMS) mission at the dawn-side high-latitude dayside boundary layer on February 25, 2016 between 18:55 and 20:05 UT. During this interval, MMS encountered both the inner and outer boundary layers with quasiperiodic low frequency fluctuations in all plasma and field parameters. The frequency analysis and growth rate calculations are consistent with the Kelvin-Helmholtz instability (KHI). The intervals within the low frequency wave structures contained several counter-streaming, low-(0-200 eV) and mid-energy (200 eV-2 keV) electrons in the loss cone and trapped energetic (70-600 keV) electrons in alternate intervals. The counter-streaming electron intervals were associated with large-magnitude field-aligned Poynting fluxes. Burst mode data at the large Alfvén velocity gradient revealed a strong correlation between counter streaming electrons, enhanced parallel electron temperatures, strong antifield aligned wave Poynting fluxes, and wave activity from sub-proton cyclotron frequencies extending to electron cyclotron frequency. Waves were identified as Kinetic Alfvén waves but their contribution to parallel electron heating was not sufficient to explain the >100 eV electrons, and rapid nonadiabatic heating of the boundary layer as determined by the characteristic heating frequency, derived here for the first time. Plain Language Summary Electrons, The Riders of the Space Hurricane: Earth's magnetic field forms a barrier in the solar wind, called the magnetosphere, which provides some shielding against solar radiation and galactic cosmic rays. However, this shield can be penetrated by process called magnetic reconnection, and secondary processes created by giant "fluid-scale" space hurricanes (typically 20,000-36,000 km in wave length) aka Kelvin-Helmholtz (KH) waves that are whipped along the magnetic barrier by solar wind flow. One of the puzzling problems of the Earth's magnetosphere is that it is so hot: both electrons and ions are heated to tens of millions of degrees when they get transported from solar wind through the Earth's magnetic barrier. This article shows observations of multiscale wave structures, spanning the fluid-scales, ion scales and electron scales detected by the NASA's magnetosphere multiscale mission consisting of four satellites. We show how these large-scale waves contain ion and electron scale waves that are able to produce some of the observed electron heating and acceleration. We "fingerprint" the exact plasma wave modes (tornadoes) inside the space hurricane that are responsible for resonantly whipping and transferring the wave energy to the electrons surfing the wave. NYKYRI ET AL.

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Section: Scatter Plot Characterization Of Boundary Layer Plasma and Vmentioning

confidence: 83%

MMS Observations of the Multiscale Wave Structures and Parallel Electron Heating in the Vicinity of the Southern Exterior Cusp

Nykyri

Burkholder

et al. 2021

JGR Space Physics

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“…No particular dawn-dusk asymmetry is reported by Lin et al (2014). It has to be noted that a revisit of THEMIS case studies events led to the following conclusion: the lower density and faster than sheath marker for KHI rolled up vortices proposed by shall be used with great caution for plasma observations at the dayside magnetopause, especially sunward of the terminator (Plaschke et al 2014). In other words, a few of the events listed in the above-mentioned studies may not be genuine crossing of KHI rolled up vortices.…”

Section: Multi-spacecraft Visionmentioning

confidence: 95%

Kelvin–Helmholtz Instability: Lessons Learned and Ways Forward

Masson

Nykyri

2018

Space Sci Rev

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The Kelvin-Helmholtz instability (KHI) is a ubiquitous phenomenon across the Universe, observed from 500 m deep in the oceans on Earth to the Orion molecular cloud. Over the past two decades, several space missions have enabled a leap forward in our understanding of this phenomenon at the Earth's magnetopause. Key results obtained by these missions are first presented, with a special emphasis on Cluster and THEMIS. In particular, as an ideal instability, the KHI was not expected to produce mass transport. Simulations, later confirmed by spacecraft observations, indicate that plasma transport in Kelvin-Helmholtz (KH) vortices can arise during non-linear stage of its development via secondary process. In addition to plasma transport, spacecraft observations have revealed that KHI can also lead to significant ion heating due to enhanced ion-scale wave activity driven by the KHI. Finally, we describe what are the upcoming observational opportunities in 2018-2020, thanks to a unique constellation of multi-spacecraft missions including: MMS, Cluster, THEMIS, Van Allen Probes and Swarm.

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“…Thus, the less dense part of the vortex rotates faster than the denser part. Such low density, accelerated magnetosphere plasma can be exposed in a ρ (or number density N ) versus V X scatter plot, where the KHW or vortex, exhibits a distinct pattern 45 46 47 . This is demonstrated in Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

Ubiquity of Kelvin–Helmholtz waves at Earth’s magnetopause

2015

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Magnetic reconnection is believed to be the dominant process by which solar wind plasma enters the magnetosphere. However, for periods of northward interplanetary magnetic field (IMF) reconnection is less likely at the dayside magnetopause, and Kelvin–Helmholtz waves (KHWs) may be important agents for plasma entry and for the excitation of ultra-low-frequency (ULF) waves. The relative importance of KHWs is controversial because no statistical data on their occurrence frequency exist. Here we survey 7 years of in situ data from the NASA THEMIS (Time History of Events and Macro scale Interactions during Substorms) mission and find that KHWs occur at the magnetopause ∼19% of the time. The rate increases with solar wind speed, Alfven Mach number and number density, but is mostly independent of IMF magnitude. KHWs may thus be more important for plasma transport across the magnetopause than previously thought, and frequently drive magnetospheric ULF waves.

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Alternative interpretation of results from Kelvin‐Helmholtz vortex identification criteria

Cited by 11 publications

References 24 publications

MMS Observations of the Multiscale Wave Structures and Parallel Electron Heating in the Vicinity of the Southern Exterior Cusp

MMS Observations of the Multiscale Wave Structures and Parallel Electron Heating in the Vicinity of the Southern Exterior Cusp

Kelvin–Helmholtz Instability: Lessons Learned and Ways Forward

Ubiquity of Kelvin–Helmholtz waves at Earth’s magnetopause

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