ORCID Profile
0000-0002-5619-1577
Current Organisation
University of Colorado at Boulder
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Publisher: American Physical Society (APS)
Date: 29-07-2008
Publisher: American Geophysical Union (AGU)
Date: 12-2019
DOI: 10.1029/2019JA027228
Abstract: Magnetic reconnection at the subsolar magnetopause is persistently accompanied by strong fluctuations of the magnetic field ( B ), plasma density ( n ), and all components of the electric field ( E ) and current ( J ). The strongest fluctuations are at frequencies below the lower hybrid frequency and observed in a thin, intense current sheet adjacent to the electron diffusion region. In this current sheet, the background magnitudes of B and n are changing considerably, creating an inhomogeneous plasma environment. We show that the fluctuations in B and n are consistent with an oscillatory displacement of the current sheet in the surface normal direction. The displacement is propagating parallel to the magnetic reconnection X line. Wavelengths are on the order of or longer than the thickness of the current sheet to which they are confined, so we label these waves electromagnetic drift waves. E and J fluctuations are more complex than a simple displacement. They have significant variations in the component along B , which suggest that the drift waves also may be confined along B . The current sheet is supported by an electron drift driven by normal electric field, which, in turn, is balanced by an ion pressure gradient. We suggest that wave growth comes from an instability related to the drift between the electrons and ions. We discuss the possibility that drift waves can displace or penetrate into the electron diffusion region giving magnetic reconnection three‐dimensional structure. Drift waves may corrugate the X line, possibly breaking the X line and generating turbulence.
Publisher: American Geophysical Union (AGU)
Date: 05-2017
DOI: 10.1002/2017JA024062
Publisher: American Geophysical Union (AGU)
Date: 09-04-2017
DOI: 10.1002/2016GL072493
Publisher: American Geophysical Union (AGU)
Date: 06-2018
DOI: 10.1029/2018JA025245
Publisher: American Geophysical Union (AGU)
Date: 03-2018
DOI: 10.1002/2017JA024537
Publisher: American Geophysical Union (AGU)
Date: 10-2016
DOI: 10.1002/2016JA023051
Abstract: The Magnetospheric Multiscale mission has demonstrated the frequent presence of reconnection exhausts at thin current sheets within Kelvin‐Helmholtz (KH) waves at the flank magnetopause. Motivated by these recent observations, we performed a statistical analysis of the boundary layers on the magnetosheath side of all KH current sheets on 8 September 2015. We show 86% consistency between the exhaust flows and particle leakage in the magnetosheath boundary layers but further highlight the very frequent presence of additional boundary layer signatures that do not come from the locally observed reconnection exhausts. These additional electron and ion boundary layers, of various durations and at various positions with respect to the leading and trailing boundaries of the KH waves, signal connections to reconnection sites at other locations. Based on the directionality and extent of these layers, we provide an interpretation whereby complex magnetic topologies can arise within KH waves from the combination of reconnection in the equatorial plane and at midlatitudes in the Southern and Northern Hemispheres, where additional reconnection sites are expected to be triggered by the three‐dimensional field lines interweaving induced by the KH waves at the flanks (owing to differential flow and magnetic field shear with latitude). The present event demonstrates that the three‐dimensional development of KH waves can induce plasma entry (through reconnection at both midlatitude and equatorial regions) already sunward of the terminator where the instability remains in its linear stage.
Publisher: American Geophysical Union (AGU)
Date: 12-2019
DOI: 10.1029/2019JA027275
Abstract: We present a model of electromagnetic drift waves in the current sheet adjacent to magnetic reconnection at the subsolar magnetopause. These drift waves are potentially important in governing 3‐D structure of subsolar magnetic reconnection and in generating turbulence. The drift waves propagate nearly parallel to the X line and are confined to a thin current sheet. The scale size normal to the current sheet is significantly less than the ion gyroradius and can be less than or on the order of the wavelength. The waves also have a limited extent along the magnetic field ( B ), making them a three‐dimensional eigenmode structure. In the current sheet, the background magnitudes of B and plasma density change significantly, calling for a treatment that incorporates an inhomogeneous plasma environment. Using detailed examination of Magnetospheric Multiscale observations, we find that the waves are best represented by series of electron vortices, superimposed on a primary electron drift, that propagate along the current sheet (parallel to the X line). The waves displace or corrugate the current sheet, which also potentially displaces the electron diffusion region. The model is based on fluid behavior of electrons, but ion motion must be treated kinetically. The strong electron drift along the X line is likely responsible for wave growth, similar to a lower hybrid drift instability. Contrary to a classical lower hybrid drift instability, however, the strong changes in the background B and n o , the normal confinement to the current sheet, and the confinement along B are critical to the wave description.
Publisher: American Geophysical Union (AGU)
Date: 05-2019
DOI: 10.1002/2017JA024024
No related grants have been discovered for Stefan Eriksson.