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 = {Eggington, JWB and Eastwood, JP and Mejnertsen, L and Desai, RT and Chittenden, JP},
doi = {10.1029/2019ja027510},
journal = {Journal of Geophysical Research: Space Physics},
pages = {1--17},
title = {Dipole tilt effect on magnetopause reconnection and the steadystate magnetosphereionosphere system: global MHD simulation},
url = {},
volume = {125},
year = {2020}

RIS format (EndNote, RefMan)

AB - The Earth’s dipole tilt angle changes both diurnally and seasonally and introduces numerous variabilities in the coupled magnetosphereionosphere system. By altering the location and intensity of magnetic reconnection, the dipole tilt influences convection on a global scale. However, due to the nonlinear nature of the system, various other effects like dipole rotation, varying IMF orientation and nonuniform ionospheric conductance can smear tilt effects arising purely from changes in coupling with the solar wind. To elucidate the underlying tilt angledependence, we perform MHD simulations of the steadystate magnetosphereionosphere system under purely southward IMF conditions for tilt angles from 0°90°. We identify the location of the magnetic separator in each case, and find that an increasing tilt angle shifts the 3D Xline southward on the magnetopause due to changes in magnetic shear angle. The separator is highly unsteady above 50° tilt angle, characteristic of regular FTE generation on the magnetopause. The reconnection rate drops as the tilt angle becomes large, but remains continuous across the dayside such that the magnetosphere is open even for 90°. These trends map down to the ionosphere, with the polar cap contracting as the tilt angle increases, and regionI fieldaligned current (FAC) migrating to higher latitudes with changing morphology. The tilt introduces a northsouth asymmetry in magnetospheric convection, thus driving more FAC in the northern (sunwardfacing) hemisphere for large tilt angles than in the south independent of conductance. These results highlight the strong sensitivity to onset time in the potential impact of a severe space weather event.
AU - Eggington,JWB
AU - Eastwood,JP
AU - Mejnertsen,L
AU - Desai,RT
AU - Chittenden,JP
DO - 10.1029/2019ja027510
EP - 17
PY - 2020///
SN - 2169-9380
SP - 1
TI - Dipole tilt effect on magnetopause reconnection and the steadystate magnetosphereionosphere system: global MHD simulation
T2 - Journal of Geophysical Research: Space Physics
UR -
UR -
UR -
VL - 125
ER -