The University of Southampton
University of Southampton Institutional Repository

MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence

MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence
MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence

We identify the electron diffusion region (EDR) of a guide field dayside reconnection site encountered by the Magnetospheric Multiscale (MMS) mission and estimate the terms in generalized Ohm's law that controlled energy conversion near the X-point. MMS crossed the moderate-shear (∼130°) magnetopause southward of the exact X-point. MMS likely entered the magnetopause far from the X-point, outside the EDR, as the size of the reconnection layer was less than but comparable to the magnetosheath proton gyroradius, and also as anisotropic gyrotropic "outflow" crescent electron distributions were observed. MMS then approached the X-point, where all four spacecraft simultaneously observed signatures of the EDR, for example, an intense out-of-plane electron current, moderate electron agyrotropy, intense electron anisotropy, nonideal electric fields, and nonideal energy conversion. We find that the electric field associated with the nonideal energy conversion is (a) well described by the sum of the electron inertial and pressure divergence terms in generalized Ohms law though (b) the pressure divergence term dominates the inertial term by roughly a factor of 5:1, (c) both the gyrotropic and agyrotropic pressure forces contribute to energy conversion at the X-point, and (d) both out-of-the-reconnection-plane gradients (∂/∂M) and in-plane (∂/∂L,N) in the pressure tensor contribute to energy conversion near the X-point. This indicates that this EDR had some electron-scale structure in the out-of-plane direction during the time when (and at the location where) the reconnection site was observed.

Magnetic reconnection, Magnetopause reconnection, Magnetospheric Multiscale, Turbulence
2169-9380
1806-1821
Genestreti, K.J.
8a3d3873-ed40-4704-a82d-c4e682ef529d
Varsani, A.
487456f1-132a-4784-8964-f3847184ea23
Burch, J.L.
bea98639-6817-4b73-a91d-a0de40632bea
Cassak, P.A.
d26a5fc1-c3c0-465e-8402-cbd556db2438
Torbert, R.B.
dfb49866-d44d-4404-81cd-22cef59d8f03
Nakamura, R.
32e21fb4-3867-4da1-8d1a-657b26a11bae
Ergun, R.E.
29d9ee4e-c45f-4e74-b478-3131183c6602
Phan, T.D.
f20f98b8-998b-4139-ad12-10a58a5b30e2
Toledo-Redondo, S.
dd6aa9b0-16f6-49ef-89a9-913d6954df3e
Hesse, M.
46b66c16-ab4b-442d-b109-69aaa0dd51d0
Wang, S.
7841864a-7ab0-43ca-99ce-a72afde68009
Giles, B.L.
eceb7be2-b272-40cb-a9af-82687b2708fd
Russell, C.T.
0beb88bf-9d0e-4b75-80ae-61ba3776ce59
Vörös, Z.
06f6dd55-7b4e-45cd-8785-77d37dc5f85b
Hwang, K.J.
c1ba4bc9-72c0-4af5-9d4a-871deafaf342
Eastwood, J.P.
2ad075de-b753-4335-9e05-c8c73b4d1800
Lavraud, B.
0aa68373-2a9a-40e8-9991-a379b8c07328
Escoubet, C.P.
4388461f-bb11-4f16-bb3b-17bd5b77f4d2
Fear, R.C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Khotyaintsev, Y.
93eb939d-f13c-4b3e-ac38-2fd9e796f4dd
Nakamura, T.K.M.
5d473ada-8ee3-46c4-9221-74cb9c7a6cf2
Webster, J.M.
51bce079-b464-4cb8-bea3-d2b98e4c0d28
Baumjohann, W.
86331e51-f16a-4cd9-83e4-5c046b05631c
Genestreti, K.J.
8a3d3873-ed40-4704-a82d-c4e682ef529d
Varsani, A.
487456f1-132a-4784-8964-f3847184ea23
Burch, J.L.
bea98639-6817-4b73-a91d-a0de40632bea
Cassak, P.A.
d26a5fc1-c3c0-465e-8402-cbd556db2438
Torbert, R.B.
dfb49866-d44d-4404-81cd-22cef59d8f03
Nakamura, R.
32e21fb4-3867-4da1-8d1a-657b26a11bae
Ergun, R.E.
29d9ee4e-c45f-4e74-b478-3131183c6602
Phan, T.D.
f20f98b8-998b-4139-ad12-10a58a5b30e2
Toledo-Redondo, S.
dd6aa9b0-16f6-49ef-89a9-913d6954df3e
Hesse, M.
46b66c16-ab4b-442d-b109-69aaa0dd51d0
Wang, S.
7841864a-7ab0-43ca-99ce-a72afde68009
Giles, B.L.
eceb7be2-b272-40cb-a9af-82687b2708fd
Russell, C.T.
0beb88bf-9d0e-4b75-80ae-61ba3776ce59
Vörös, Z.
06f6dd55-7b4e-45cd-8785-77d37dc5f85b
Hwang, K.J.
c1ba4bc9-72c0-4af5-9d4a-871deafaf342
Eastwood, J.P.
2ad075de-b753-4335-9e05-c8c73b4d1800
Lavraud, B.
0aa68373-2a9a-40e8-9991-a379b8c07328
Escoubet, C.P.
4388461f-bb11-4f16-bb3b-17bd5b77f4d2
Fear, R.C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Khotyaintsev, Y.
93eb939d-f13c-4b3e-ac38-2fd9e796f4dd
Nakamura, T.K.M.
5d473ada-8ee3-46c4-9221-74cb9c7a6cf2
Webster, J.M.
51bce079-b464-4cb8-bea3-d2b98e4c0d28
Baumjohann, W.
86331e51-f16a-4cd9-83e4-5c046b05631c

Genestreti, K.J., Varsani, A., Burch, J.L., Cassak, P.A., Torbert, R.B., Nakamura, R., Ergun, R.E., Phan, T.D., Toledo-Redondo, S., Hesse, M., Wang, S., Giles, B.L., Russell, C.T., Vörös, Z., Hwang, K.J., Eastwood, J.P., Lavraud, B., Escoubet, C.P., Fear, R.C., Khotyaintsev, Y., Nakamura, T.K.M., Webster, J.M. and Baumjohann, W. (2018) MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence. Journal of Geophysical Research: Space Physics, 123 (3), 1806-1821. (doi:10.1002/2017JA025019).

Record type: Article

Abstract

We identify the electron diffusion region (EDR) of a guide field dayside reconnection site encountered by the Magnetospheric Multiscale (MMS) mission and estimate the terms in generalized Ohm's law that controlled energy conversion near the X-point. MMS crossed the moderate-shear (∼130°) magnetopause southward of the exact X-point. MMS likely entered the magnetopause far from the X-point, outside the EDR, as the size of the reconnection layer was less than but comparable to the magnetosheath proton gyroradius, and also as anisotropic gyrotropic "outflow" crescent electron distributions were observed. MMS then approached the X-point, where all four spacecraft simultaneously observed signatures of the EDR, for example, an intense out-of-plane electron current, moderate electron agyrotropy, intense electron anisotropy, nonideal electric fields, and nonideal energy conversion. We find that the electric field associated with the nonideal energy conversion is (a) well described by the sum of the electron inertial and pressure divergence terms in generalized Ohms law though (b) the pressure divergence term dominates the inertial term by roughly a factor of 5:1, (c) both the gyrotropic and agyrotropic pressure forces contribute to energy conversion at the X-point, and (d) both out-of-the-reconnection-plane gradients (∂/∂M) and in-plane (∂/∂L,N) in the pressure tensor contribute to energy conversion near the X-point. This indicates that this EDR had some electron-scale structure in the out-of-plane direction during the time when (and at the location where) the reconnection site was observed.

Full text not available from this repository.

More information

Accepted/In Press date: 5 February 2018
e-pub ahead of print date: 6 March 2018
Keywords: Magnetic reconnection, Magnetopause reconnection, Magnetospheric Multiscale, Turbulence

Identifiers

Local EPrints ID: 421602
URI: https://eprints.soton.ac.uk/id/eprint/421602
ISSN: 2169-9380
PURE UUID: 15de2ac6-d211-415c-947f-9c00f716d095
ORCID for R.C. Fear: ORCID iD orcid.org/0000-0003-0589-7147

Catalogue record

Date deposited: 15 Jun 2018 16:31
Last modified: 10 Dec 2019 01:34

Export record

Altmetrics

Contributors

Author: K.J. Genestreti
Author: A. Varsani
Author: J.L. Burch
Author: P.A. Cassak
Author: R.B. Torbert
Author: R. Nakamura
Author: R.E. Ergun
Author: T.D. Phan
Author: S. Toledo-Redondo
Author: M. Hesse
Author: S. Wang
Author: B.L. Giles
Author: C.T. Russell
Author: Z. Vörös
Author: K.J. Hwang
Author: J.P. Eastwood
Author: B. Lavraud
Author: C.P. Escoubet
Author: R.C. Fear ORCID iD
Author: Y. Khotyaintsev
Author: T.K.M. Nakamura
Author: J.M. Webster
Author: W. Baumjohann

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×