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Kelvin-Helmholtz instability

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Kelvin-Helmholtz Instability: Lessons Learned And Ways Forward, A. Masson, K. Nykyri Jun 2018

Kelvin-Helmholtz Instability: Lessons Learned And Ways Forward, A. Masson, K. Nykyri

Publications

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 ...


Asymmetric Kelvin-Helmholtz Instability At Jupiter's Magnetopause Boundary: Implications For Corotation-Dominated Systems, B. Zhang, P. A. Delamere, X. Ma, B. Burkholder, M. Wiltberger, J. G. Lyon, V. G. Merkin, K. A. Sorathia Jan 2018

Asymmetric Kelvin-Helmholtz Instability At Jupiter's Magnetopause Boundary: Implications For Corotation-Dominated Systems, B. Zhang, P. A. Delamere, X. Ma, B. Burkholder, M. Wiltberger, J. G. Lyon, V. G. Merkin, K. A. Sorathia

Publications

The multifluid Lyon‐Fedder‐Mobarry (MFLFM) global magnetosphere model is used to study the interactions between solar wind and rapidly rotating, internally driven Jupiter magnetosphere. The MFLFM model is the first global simulation of Jupiter magnetosphere that captures the Kelvin‐Helmholtz instability (KHI) in the critically important subsolar region. Observations indicate that Kelvin‐Helmholtz vortices are found predominantly in the dusk sector. Our simulations explain that this distribution is driven by the growth of KHI modes in the prenoon and subsolar region (e.g., >10 local time) that are advected by magnetospheric flows to the dusk sector. The period of ...


Ion-Scale Wave Properties And Enhanced Ion Heating Across The Low-Latitude Boundary Layer During Kelvin-Helmholtz Instability, T. W. Moore, K. Nykyri, A. P. Dimmock Nov 2017

Ion-Scale Wave Properties And Enhanced Ion Heating Across The Low-Latitude Boundary Layer During Kelvin-Helmholtz Instability, T. W. Moore, K. Nykyri, A. P. Dimmock

Publications

In the Earth's magnetosphere, the magnetotail plasma sheet ions are much hotter than in the shocked solar wind. On the dawn sector, the cold-component ions are more abundant and hotter by 30–40% when compared to the dusk sector. Recent statistical studies of the flank magnetopause and magnetosheath have shown that the level of temperature asymmetry of the magnetosheath is unable to account for this, so additional physical mechanisms must be at play, either at the magnetopause or plasma sheet that contributes to this asymmetry. In this study, we perform a statistical analysis on the ion-scale wave properties in ...


Plasma Transport Driven By The Three-Dimensional Kelvin-Helmholtz Instability, Xuanye Ma, Peter Delamere, Antonius Otto, Brandon Burkholder Oct 2017

Plasma Transport Driven By The Three-Dimensional Kelvin-Helmholtz Instability, Xuanye Ma, Peter Delamere, Antonius Otto, Brandon Burkholder

Publications

It has been well demonstrated that the nonlinear Kelvin‐Helmholtz (KH) instability plays a critical role for the solar wind interaction with the Earth's magnetosphere. Although the two‐dimensional KH instability has been fully explored during the past decades, more and more studies show the fundamental difference between the two‐ and three‐dimensional KH instability. For northward interplanetary magnetic field (IMF) conditions, the nonlinear KH wave that is localized in the vicinity of the equatorial plane can dramatically bend the magnetic field line, generating strong antiparallel magnetic field components at high latitudes in both North and South Hemispheres, which ...


On The Dawn-Dusk Asymmetry Of The Kelvin-Helmholtz Instability Between 2007 And 2013, Z. W. Henry, K. Nykyri, T. W. Moore, A. P. Dimmock, X. Ma Oct 2017

On The Dawn-Dusk Asymmetry Of The Kelvin-Helmholtz Instability Between 2007 And 2013, Z. W. Henry, K. Nykyri, T. W. Moore, A. P. Dimmock, X. Ma

Publications

Using data from Time History of Events and Macroscale Interactions during Substorms (THEMIS), a statistical study was performed to determine whether a dawn-dusk asymmetry exists in the occurrence rates of the Kelvin-Helmholtz (KH) instability during Parker-Spiral (PS) and Ortho-Parker-Spiral (OPS) orientations of the interplanetary magnetic field (IMF). It is determined from the data that there is a strong preference toward the dawn side during PS orientation, and although a preference to the dusk side during OPS is suggested, this requires further study for an unambiguous confirmation. The uncertainty in the OPS result is due to a low number of events ...


Influence Of Velocity Fluctuations On The Kelvin-Helmholtz Instability And Its Associated Mass Transport, Katariina Nykyri, Xuanye Ma, Andrew Dimmock, Claire Foullon, Antonius Otto, Adnane Osmane Sep 2017

Influence Of Velocity Fluctuations On The Kelvin-Helmholtz Instability And Its Associated Mass Transport, Katariina Nykyri, Xuanye Ma, Andrew Dimmock, Claire Foullon, Antonius Otto, Adnane Osmane

Publications

Kelvin-Helmholtz instability (KHI) and associated magnetic reconnection and diffusion processes provide plasma transport from solar wind into the magnetosphere. The efficiency of this transport depends on the magnetosheath and magnetospheric plasma and field properties at the vicinity of the magnetopause. Our recent statistical study using data from the Time History of Events and Macroscale Interactions during Substorms spacecraft indicates that the amplitude of the magnetosheath velocity fluctuations perpendicular to the magnetopause can be substantial. We have performed a series of local macroscale 2.5-dimensional magnetohydrodynamic simulations of the KHI during strongly northward interplanetary magnetic field and with the initial plasma ...


Local Time Asymmetry Of Saturn's Magnetosheath Flows, B. Burkholder, P. A. Delamere, X. Ma, M. F. Thomsen, R. J. Wilson, F. Bagenal Jun 2017

Local Time Asymmetry Of Saturn's Magnetosheath Flows, B. Burkholder, P. A. Delamere, X. Ma, M. F. Thomsen, R. J. Wilson, F. Bagenal

Publications

Using gross averages of the azimuthal component of flow in Saturn's magnetosheath, we find that flows in the prenoon sector reach a maximum value of roughly half that of the postnoon side. Corotational magnetodisc plasma creates a much larger flow shear with solar wind plasma prenoon than postnoon. Maxwell stress tensor analysis shows that momentum can be transferred out of the magnetosphere along tangential field lines if a normal component to the boundary is present, i.e., field lines which pierce the magnetopause. A Kelvin‐Helmholtz unstable flow gives rise to precisely this situation, as intermittent reconnection allows the ...


Interaction Of Magnetic Reconnection And Kelvin-Helmholtz Modes For Large Magnetic Shear: 1. Kelvin-Helmholtz Trigger, Xuanye Ma, Antonius Otto, Peter A. Delamere Feb 2014

Interaction Of Magnetic Reconnection And Kelvin-Helmholtz Modes For Large Magnetic Shear: 1. Kelvin-Helmholtz Trigger, Xuanye Ma, Antonius Otto, Peter A. Delamere

Publications

At the Earth's magnetopause, both magnetic reconnection and the Kelvin‐Helmholtz (KH) instability can operate simultaneously for southward interplanetary magnetic field conditions. The dynamic evolution of such a system can be expected to depend on the importance of KH wave evolution versus reconnection and therefore on the respective initial perturbations. In this study, a series of local three‐dimensional MHD and Hall MHD simulations are carried out to investigate the situation where the Kelvin‐Helmholtz instability is initially the primary process. It is demonstrated that magnetic reconnection is driven and strongly modified by nonlinear KH waves. The highest reconnection ...


Interaction Of Magnetic Reconnection And Kelvin-Helmholtz Modes For Large Magnetic Shear: 2. Reconnection Trigger, Xuanye Ma, Antonius Otto, Peter A. Delamere Feb 2014

Interaction Of Magnetic Reconnection And Kelvin-Helmholtz Modes For Large Magnetic Shear: 2. Reconnection Trigger, Xuanye Ma, Antonius Otto, Peter A. Delamere

Publications

A typical property of magnetopause reconnection is a significant perpendicular shear flow due to the fast streaming magnetosheath plasma. Therefore, the magnetopause represents a large magnetic and flow shear boundary during periods of southward interplanetary magnetic field, which can be unstable to Kelvin‐Helmholtz (KH) modes and to magnetic reconnection. A series of local three‐dimensional MHD and Hall MHD simulations is carried out to investigate the interaction of reconnection and nonlinear KH waves considering magnetic reconnection as the primary process. It is demonstrated that the onset reconnection causes a thinning of the shear flow layer, thereby generating small wavelength ...


First Magnetic Seismology Of The Cme Reconnection Outflow Layer In The Low Corona With 2.5-D Mhd Simulations Of The Kelvin-Helmholtz Instability, Katariina Nykyri, Claire Foullon Aug 2013

First Magnetic Seismology Of The Cme Reconnection Outflow Layer In The Low Corona With 2.5-D Mhd Simulations Of The Kelvin-Helmholtz Instability, Katariina Nykyri, Claire Foullon

Publications

For conditions observed in the low corona, we perform 2.5-D magnetohydrodynamic (MHD) simulations of the Kelvin-Helmholtz instability (KHI) at the surface of a coronal mass ejection (CME). We match the observed time development of the KHI with simulated growth from 110 MHD experiments representing a parametric range of realistic magnetic field strengths and orientations and two key values of the velocity shear, ΔV, inferred from observations. The results are field strengths Be≈ 8–9 G and Bs≈ 10–11 G in the CME reconnection outflow layer and the surrounding sheath, respectively, for ΔV≈770kms−1; for nearly perpendicular orientation ...


Impact Of Mhd Shock Physics On Magnetosheath Symmetry And Kelvin-Helmholtz Instability, K. Nykyri Aug 2013

Impact Of Mhd Shock Physics On Magnetosheath Symmetry And Kelvin-Helmholtz Instability, K. Nykyri

Publications

We have performed 13 three-dimensional global magnetohydrodynamic (MHD) simulations of the magnetosheath plasma and magnetic field properties for Parker spiral (PS) and ortho-Parker spiral interplanetary magnetic field (IMF) orientations corresponding to a wide range of solar wind plasma conditions. To study the growth of the Kelvin-Helmholtz instability on the dawn and dusk flank magnetopause, we have performed 26 local two-dimensional MHD simulations, with the initial conditions taken from global simulations on both sides of the velocity shear layer at the dawn-dusk terminator. These simulations indicate that while the MHD physics of the fast shocks does not directly lead to strong ...