Imperial College London

Dr Jonathan P. Eastwood

Faculty of Natural SciencesDepartment of Physics

Senior Lecturer



+44 (0)20 7594 8101jonathan.eastwood Website




6M63Blackett LaboratorySouth Kensington Campus






BibTex format

author = {Genestreti, KJ and Varsani, A and Burch, JL and Cassak, PA and Torbert, RB and Nakamura, R and Ergun, RE and Phan, TD and Toledo-Redondo, S and Hesse, M and Wang, S and Giles, BL and Russell, CT and Vörös, Z and Hwang, KJ and Eastwood, JP and Lavraud, B and Escoubet, CP and Fear, RC and Khotyaintsev, Y and Nakamura, TKM and Webster, JM and Baumjohann, W},
doi = {10.1002/2017JA025019},
journal = {Journal of Geophysical Research: Space Physics},
pages = {1806--1821},
title = {MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence},
url = {},
volume = {123},
year = {2018}

RIS format (EndNote, RefMan)

AB - 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.
AU - Genestreti,KJ
AU - Varsani,A
AU - Burch,JL
AU - Cassak,PA
AU - Torbert,RB
AU - Nakamura,R
AU - Ergun,RE
AU - Phan,TD
AU - Toledo-Redondo,S
AU - Hesse,M
AU - Wang,S
AU - Giles,BL
AU - Russell,CT
AU - Vörös,Z
AU - Hwang,KJ
AU - Eastwood,JP
AU - Lavraud,B
AU - Escoubet,CP
AU - Fear,RC
AU - Khotyaintsev,Y
AU - Nakamura,TKM
AU - Webster,JM
AU - Baumjohann,W
DO - 10.1002/2017JA025019
EP - 1821
PY - 2018///
SN - 2169-9380
SP - 1806
TI - MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence
T2 - Journal of Geophysical Research: Space Physics
UR -
UR -
VL - 123
ER -