Title: Measurement of the Magnetic Reconnection Rate in the Earth's Magnetotail

Abstract

In the Earth's magnetotail, magnetic reconnection releases stored magnetic energy and drives magnetospheric convection. The rate at which magnetic flux is transferred from the reconnection inflow to outflow regions is determined by the reconnection electric field E_r, which is often referred to as the unnormalized reconnection rate. To better quantify the efficiency of reconnection, this electric field E_r is often normalized by the characteristic Alfvén speed and the reconnecting magnetic field. This parameter is generally called the normalized or dimensionless reconnection rate R. In this paper, we employ a two–dimensional fully kinetic simulation to model a magnetotail reconnection event with weak geomagnetic activity (<200 nT of the AE index) observed by the Magnetospheric Multiscale (MMS) mission on 11 July 2017. We obtain R and E_r from direct measurements in the diffusion region and indirect measurements of the rate at the separatrix using a recently proposed remote sensing technique. The measured normalized rate for this MMS event is R ~0.15–0.2, consistent with theoretical and simulation models of fast collisionless reconnection. This corresponds to an unnormalized rate of E_r ~2–3 mV/m. Based on quantitative consistencies between the simulation and the MMS observations, we conclude that our estimates of the reconnection rates aremore » reasonably accurate. Here, given that past studies have found E_r of the order ~10 mV/m during strong geomagnetic substorms, these results indicate that the local E_r in magnetotail reconnection may be an important parameter controlling the amplitude of geomagnetic disturbances.« less

Authors:

Nakamura, Takuma K. M.  ^[1];

• Search DOE PAGES for author "Nakamura, Takuma K. M."
• Search DOE PAGES for ORCID "0000-0003-4550-2947"

Genestreti, K. J.  ^[2];

• Search DOE PAGES for author "Genestreti, K. J."
• Search DOE PAGES for ORCID "0000-0001-6890-2973"

Liu, Yi -Hsin  ^[3];

• Search DOE PAGES for author "Liu, Yi -Hsin"
• Search DOE PAGES for ORCID "0000-0001-5880-2645"

Nakamura, R.  ^[1];

• Search DOE PAGES for author "Nakamura, R."
• Search DOE PAGES for ORCID "0000-0002-2620-9211"

Teh, W. -L.  ^[4];

• Search DOE PAGES for author "Teh, W. -L."
• Search DOE PAGES for ORCID "0000-0002-7114-1543"

Hasegawa, H.  ^[5];

• Search DOE PAGES for author "Hasegawa, H."
• Search DOE PAGES for ORCID "0000-0002-1172-021X"

Daughton, William Scott  ^[6];

• Search DOE PAGES for author "Daughton, William Scott"
• Search DOE PAGES for ORCID "0000-0003-1051-7559"

Hesse, M.  ^[7];

• Search DOE PAGES for author "Hesse, M."
• Search DOE PAGES for ORCID "0000-0003-0377-9673"

Torbert, R. B.  ^[8];

• Search DOE PAGES for author "Torbert, R. B."
• Search DOE PAGES for ORCID "0000-0001-7188-8690"

Burch, J. L.  ^[9];

• Search DOE PAGES for author "Burch, J. L."
• Search DOE PAGES for ORCID "0000-0003-0452-8403"

Giles, B. L.  ^[10]

• Search DOE PAGES for author "Giles, B. L."
• Search DOE PAGES for ORCID "0000-0001-8054-825X"

---

+ Show Author Affiliations

1. Austrian Academy of Sciences, Graz (Austria)
2. Austrian Academy of Sciences, Graz (Austria); Univ. of New Hampshire, Durham, NH (United States)
3. Dartmouth College, Hanover, NH (United States)
4. Univ. Kebangsaan Malaysia, Bangi (Malaysia)
5. JAXA, Sagamihara (Japan)
6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
7. Univ. of Bergen, Bergen (Norway); Southwest Research Institute, San Antonio, TX (United States)
8. Univ. of New Hampshire, Durham, NH (United States); Southwest Research Institute, San Antonio, TX (United States)
9. Southwest Research Institute, San Antonio, TX (United States)
10. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)

Publication Date:

Sat Sep 15 00:00:00 EDT 2018

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA); USDOE

OSTI Identifier:

1483547

Report Number(s):

LA-UR-18-28888
Journal ID: ISSN 2169-9380

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Volume: 123; Journal Issue: 11; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; magnetic reconnection; reconnection rate; MMS; magnetotail; PIC simulation; geomagnetic activity