EDR signatures observed by MMS in the 16 October event presented in a 2‐D parametric space. Issue 3 (22nd March 2017)

• Record Type: Journal Article
• Authors: Alm, L.; Argall, M. R.; Torbert, R. B.; Farrugia, C. J.; Burch, J. L.; Ergun, R. E.; Russell, C. T.; Strangeway, R. J.; Khotyaintsev, Y. V.; Lindqvist, P.‐A.; Marklund, G. T.; Giles, B. L.; Shuster, J.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 3(2017)
• Page Start: 3262
• Page End: 3276
• Publication Date: 2017-03-22
• Subjects: magnetic reconnection -- electron diffusion region -- MMS -- parametric space -- multispacecraft -- asymmetric reconnection; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2016JA023788
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We present a method for mapping the position of satellites relative to the X line using the measured B L and B N components of the magnetic field and apply it to the Magnetospheric multiscale (MMS) encounter with the electron diffusion region (EDR) which occurred on 13:07 UT on 16 October 2015. Mapping the data to our parametric space succeeds in capturing many of the signatures associated with magnetic reconnection and the electron diffusion region. This offers a method for determining where in the reconnection region the satellites were located. In addition, parametric mapping can also be used to present data from numerical simulations. This facilitates comparing data from simulations with data from in situ observations as one can avoid the complicated process using boundary motion analysis to determine the geometry of the reconnection region. In parametric space we can identify the EDR based on the collocation of several reconnection signatures, such as electron nongyrotropy, electron demagnetization, parallel electric fields, and energy dissipation. The EDR extends 2–3 km in the normal direction and in excess of 20 km in the tangential direction. It is clear that the EDR occurs on the magnetospheric side of the topological X line, which is expected in asymmetric reconnection. Furthermore, we can observe a north‐south asymmetry, where the EDR occurs north of the peak in out‐of‐plane current, which may be due to the small but finite guide field. Key Points: Mapping data to a parametric space captures many of the typical EDR signatures The EDR is offset northward and earthward relative to the topological X line EDR extent is 2–3 km in the normal direction, >20 km in the tangential direction